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Sizing Gravity conversion circulators.....Boilerpro

Boilerpro
Boilerpro Member Posts: 410
Mark's and Steamhead's comments about flow being very slow until the system got warmed up got me thinking. Maybe this is why so many old time contractors insist on sizing boilers to the radiation.....it gets the flow moving faster if the boiler temp rises quickly. They later added pumps to thier new boilers, but forget the reason why they were making those boilers so big was for circulation, not heat. Maybe another great mystery solved.

Boilerpro
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Comments

  • Boilerpro
    Boilerpro Member Posts: 410
    Sizing Circulators

    Continue to do alot of gravity conversions and sizing these pumps is again on my mind. This is the info I have so far:

    Gravity systems usually were designed for a 30F to 40F delta tee from boiler supply to boiler return.... 180F out 140F to 150F return.

    Most modern systems were designed for a 20F delta tee.

    The radiation on many gravity systems is greatly oversized.... largely due to insulation added to wall/ ceilings, storms added, etc.

    Steamhead's essay at Hot Tech topics says to base the size of the circ. on gravity conversion on radiation size and use a circ 50% Larger than that of a modern system. I.E. 500 edr installed radiation times 150 btu/edr equals 75,000 btu/hr. In a modern 20F delta tee system this would be about 7.5 gpm....now we need to add another 50% which gives us about 11 gpm.

    However, many also say to try to not disturb the operation of the gravity system when installing a new boiler and pump to achieve the same flow balance To me this means we want the same flow rate through the system. In other words we need to size the system pump for the added pressure drop of our new smaller piping while maintaining the same temperature drop across the system (assuming the system still needs to put out the same amount of heat and run at 180F.... which most don't in my experience). Using the above example:
    75,000 btu/hr installed edr at, let's say, 35F delta tee.

    75,000 btu/hr divided by (8.3 x60 x 35F delta T) equals only 4.3 gpm.

    Sooooooo, Which is right 11 gpm or 4.3 gpm?

    Boilerpro
  • greg_7
    greg_7 Member Posts: 71
    pump sizes

    I'm not an expert, but I have been conducting a little experiment on my own converted gravity system.

    A 3/4" B&G 100 or the like is sort of the norm for a system pump on a gravity conversion. I used that as well.

    But I was concerned that some rads were not as warm. I have about 1,100 sq f of rads in a house nearly 4,000 sq f. I wondered how much a bigger pump would affect the system, inspite of the fact I had read all the info.

    Since it was my own home I had the luxury of time. I happened to come upon several old B&G pumps sized from 1" up to 2". I installed the 2" and found that air in the system no longer ended up at the bleeder, but instread on th3e upper floors radiators. Too much flow.

    So I have continued to switch out the pumps and now I'm at 1-1/4" and I get a little air at bleeder and some upstairs.

    The next step is to swap in the 1".

    So it seems that both practice and theory are in synch.
  • Mark J Strawcutter
    Mark J Strawcutter Member Posts: 625
    I seem to remember

    a posting from Steamhead where he says he's ended up with a Taco 005 on his own home's system (gravity conversion).

    This would seem to indicate that 4.3gpm is the right answer.

    But it would also seem he's contradicting himself :-)

    Mark
  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928
    Delta t & Gravity Systems

    Glad someone mentioned the HIGH delta t that many gravity systems were designed around.

    It ties into my ideas of why the rads are so big to begin with.

    A good post-WWII heating book shows equations for computing the flow in gravity systems--they're quite hairy. The goal is a very narrow specific velocity range in the pipes. You then computed the actual amount of flow based on this velocity and ensured it was adequate to serve the radiation attached from that point on. Process repeats throughout the system--but since changing one thing later affects everything before it gets strange. To make it even more complex changing the supply temperature changes the delta t which changes the velocity which changes the flow...argh!

    The good thing is that the "old way" of sizing the boiler/pipes/radiation where you choose a boiler based on supplied radiation; initial main size based on total output and subsequent main size based on cross-section of rad valves still to be served usually came pretty close to the difficult calculations. I'm not even certain that the equations existed back then anyway...

    Since the motive force in a gravity system is the difference in density (temperature) of the water between the supply and return, you can actually view the radiation as being the circulator. Since it's the prime place where heat is extracted, it really is providing the motive power for circulation. Consequently, the rads have to be large enough not only to heat the room, but to extract enough heat from the supply to create circulation.

    Try to extract too much heat (too large a rad or too small a pipe) and the delta t increases to a point so high that the velocity it requires to maintain the delta t overwhelms the friction loss of the piping.

    Try to extract too little heat (too small a rad or too large a pipe) and the delta t decreases so much that you loose the motive force for driving the system in the first place.

    The real balancing act came from sizing the pipes and rads so that the VELOCITY remained nearly constant through the entire system.

    When you consider multi-floor applications where there are different elevations on the rads (thus a different velocity for an otherwise idential rad/pipe combination) it becomes a near wonder that these ever worked to begin with. You'll understand why those "restrictor plates" are sometimes there--generally when the "rule of thumb" sizing methods produced a very different result than the actual calculations would have produced.

    Remember also that as long as that coal fire burned, these systems produced heat. But it wasn't too practical (or even possible) to keep the fire "just right" at all times. They needed the ability to really "crank" the heat to compensate for the fire nearly dying on a cold night--thus that 180 degree supply temp ability. If you remember that tendency to "air the house" each day, they REALLY needed to be able to crank the heat...

    Go back again to VELOCITY. It was SLOW. The BTUs "hung out" in the radiator for quite a while and many of them were able to find their way to the room--thus the hefty delta t AT DESIGN TEMP. Since the boiler (ideally) was always supplying heat, the rads didn't go through hot & cold cycles--they just got warmer as the fire was made bigger as it got colder outside. If everything was sized perfectly, the velocity would increase proportionally to the size of the fire/temperature of the water BUT the velocity would stay the same through the system as a whole at any given supply/return temp combination.

    NOW, throw in a digitally controlled heat source (the boiler with thermostat) and a circulator.

    Velocity no longer changes with supply temperature. Supply temperature varies GREATLY and the rads go through "hot and cold" cycles. It's now behaving much more like a steam system--just at lower temperature--and the mass of the radiators keeps the space temperature from varying too much.

    Delta t no longer has slow, gentle changes as it did when operating under gravity. When the circulator is off the water in the rads cools greatly. When the circulator kicks in, delta t is huge--thus the need for protection from low return temps. BUT velocity is much higher--and constant--than under gravity and the BTUs don't "hang out" in the rads as long--thus fewer make their way to the room. It's the added velocity alone that makes enough BTUs available to heat the space.

    As the weather cools outside the circulator runs more frequently and there is less on-off difference in temperature of the water in the radiators. Delta t actually decreases! This is the EXACT opposite of what happens in a system with gravity flow. Fewer and fewer BTUs make their way from the water to the space with each pass through the radiator. You have to keep the velocity (flow) up to ensure enough BTUs can make their way to highest, farthest rad. This rad will have the highest delta t (lowest velocity) in the system.

    FINALLY:

    Sooooooo, Which is right 11 gpm or 4.3 gpm?

    The 11 gpm is the most correct figure in most every instance:

    With simple control (on-off circulator): You need this amount of flow so that you put enough BTUs in the lowest, closest rad OFTEN ENOUGH to liberate enough heat at design. This rad will have the lowest delta t (highest velocity) in the system. Remember that flow restriction is virtually non-existant in these systems thus the "downsizing" of the mains at the boiler and the high flow/low head circulator. As long as the velocity is not so high as to prevent any BTUs from getting off in the rads, you won't have a problem. If this only happens on an occasional rad (likely ones closest to the boiler) you can "fix" it by going back to the restrictor plates. Remember that you likely have a bypass line installed around the boiler anyway so a good chunk of flow never makes it to the rads to begin with.

    If you get the idea that you could eliminate the bypass by using a smaller circulator--thus trying to make it flow the way it did under gravity--watch out. You'll wind up with extraordinarily high delta t--particularly during mild weather.

    If you now think "I'm using a condensing boiler so I don't have to worry about return temp" think again. That careful balance of velocity in the gravity system DOES NOT WORK when you add forced circulation. Instead of the radiators "pulling" the water through the boiler, the circulator is now "pushing" the water through the rads. Since the circulator is now the only source of this motive power, its energy is expended in the EASIEST way possible--the path of least resistance--NOT the path through all the radiators. While every molecule of water may be moving simultaneously, they WON'T be moving at the same velocity as they did under gravity. About your ONLY prayer of getting this to work would be with a single-floor reverse-return piping arrangement.

    With constant circulation, TRVs, normal boiler: You wind up with the problem just mentioned--incredible delta t. You also have to build enough head pressure to keep the TRVs functioning so you still need the ability for high flow--you just need even more bypass around the boiler much of the time.

    With a proportionally fired condensing boiler, constant circulation and TRVs things can change. While they won't have large enough tappings to operate under gravity circulation, this should be possible: If you could somehow vary the velocity of water directly with the burner, your flow could be reduced immensely most of the time. The TRVs will even the velocity for you by adding restriction as needed. I have no idea though if the reduced electric consumption would be worth the much greater complexity--I sort of doubt it...
  • Duncan_2
    Duncan_2 Member Posts: 174
    No numbers, but an interesting experience.

    I saw a 50 room, 110 year old, three-story apartment building that had been converted from one pipe steam to two pipe hot water. There were three inch mains in the crawl space, one to one and a half inch risers to rads as I recall. Urea-formaldehyde foam insulation had been pumped into the building.

    All of the rads - at least forty or so I think - had 1/2 inch copper returns installed.

    The water in this large system was circulated with a Grundfos UP-2664. In other words, you don't need much pump.

    If it were me, I'd size the circ based on the longest run. I'd install the smaller circ between isolating flanges. If it turned out wrong, I'd switch to another pump. It's really surprising how little pump you need most of the time.

    By the way, the building owner (at the time) who did the changeover of this big old system? He was an engineer who specced circulators for commercial jobs. The building is in Cape May, NJ, 55 Jackson Street, formerly known as the Rivendale.
  • Mark J Strawcutter
    Mark J Strawcutter Member Posts: 625
    no, he's not

    Oops - was looking at the wrong pump curve.

    an 005 will give you 11gpm at 6-7ft of head (which is probably a bit on the high side for head required on a gravity conversion).

    Mark
  • Boilerpro
    Boilerpro Member Posts: 410
    Verry Interesting...

    > Glad someone mentioned the HIGH delta t that many

    > gravity systems were designed around.

    >

    > It ties

    > into my ideas of why the rads are so big to begin

    > with.

    >

    > A good post-WWII heating book shows

    > equations for computing the flow in gravity

    > systems--they're quite hairy. The goal is a very

    > narrow specific velocity range in the pipes. You

    > then computed the actual amount of flow based on

    > this velocity and ensured it was adequate to

    > serve the radiation attached from that point on.

    > Process repeats throughout the system--but since

    > changing one thing later affects everything

    > before it gets strange. To make it even more

    > complex changing the supply temperature changes

    > the delta t which changes the velocity which

    > changes the flow...argh!

    >

    > The good thing is

    > that the "old way" of sizing the

    > boiler/pipes/radiation where you choose a boiler

    > based on supplied radiation; initial main size

    > based on total output and subsequent main size

    > based on cross-section of rad valves still to be

    > served usually came pretty close to the difficult

    > calculations. I'm not even certain that the

    > equations existed back then anyway...

    >

    > Since

    > the motive force in a gravity system is the

    > difference in density (temperature) of the water

    > between the supply and return, you can actually

    > view the radiation as being the circulator.

    > Since it's the prime place where heat is

    > extracted, it really is providing the motive

    > power for circulation. Consequently, the rads

    > have to be large enough not only to heat the

    > room, but to extract enough heat from the supply

    > to create circulation.

    >

    > Try to extract too much

    > heat (too large a rad or too small a pipe) and

    > the delta t increases to a point so high that the

    > velocity it requires to maintain the delta t

    > overwhelms the friction loss of the

    > piping.

    >

    > Try to extract too little heat (too

    > small a rad or too large a pipe) and the delta t

    > decreases so much that you loose the motive force

    > for driving the system in the first place.

    >

    > The

    > real balancing act came from sizing the pipes and

    > rads so that the VELOCITY remained nearly

    > constant through the entire system.

    >

    > When you

    > consider multi-floor applications where there are

    > different elevations on the rads (thus a

    > different velocity for an otherwise idential

    > rad/pipe combination) it becomes a near wonder

    > that these ever worked to begin with. You'll

    > understand why those "restrictor plates" are

    > sometimes there--generally when the "rule of

    > thumb" sizing methods produced a very different

    > result than the actual calculations would have

    > produced.

    >

    > Remember also that as long as that

    > coal fire burned, these systems produced heat.

    > But it wasn't too practical (or even possible) to

    > keep the fire "just right" at all times. They

    > needed the ability to really "crank" the heat to

    > compensate for the fire nearly dying on a cold

    > night--thus that 180 degree supply temp ability.

    > If you remember that tendency to "air the house"

    > each day, they REALLY needed to be able to crank

    > the heat...

    >

    > Go back again to VELOCITY. It was

    > SLOW. The BTUs "hung out" in the radiator for

    > quite a while and many of them were able to find

    > their way to the room--thus the hefty delta t AT

    > DESIGN TEMP. Since the boiler (ideally) was

    > always supplying heat, the rads didn't go through

    > hot & cold cycles--they just got warmer as the

    > fire was made bigger as it got colder outside.

    > If everything was sized perfectly, the velocity

    > would increase proportionally to the size of the

    > fire/temperature of the water BUT the velocity

    > would stay the same through the system as a whole

    > at any given supply/return temp

    > combination.

    >

    > NOW, throw in a digitally

    > controlled heat source (the boiler with

    > thermostat) and a circulator.

    >

    > Velocity no

    > longer changes with supply temperature. Supply

    > temperature varies GREATLY and the rads go

    > through "hot and cold" cycles. It's now behaving

    > much more like a steam system--just at lower

    > temperature--and the mass of the radiators keeps

    > the space temperature from varying too

    > much.

    >

    > Delta t no longer has slow, gentle

    > changes as it did when operating under gravity.

    > When the circulator is off the water in the rads

    > cools greatly. When the circulator kicks in,

    > delta t is huge--thus the need for protection

    > from low return temps. BUT velocity is much

    > higher--and constant--than under gravity and the

    > BTUs don't "hang out" in the rads as long--thus

    > fewer make their way to the room. It's the added

    > velocity alone that makes enough BTUs available

    > to heat the space.

    >

    > As the weather cools

    > outside the circulator runs more frequently and

    > there is less on-off difference in temperature of

    > the water in the radiators. Delta t actually

    > decreases! This is the EXACT opposite of what

    > happens in a system with gravity flow. Fewer and

    > fewer BTUs make their way from the water to the

    > space with each pass through the radiator. You

    > have to keep the velocity (flow) up to ensure

    > enough BTUs can make their way to the

    > room.

    >

    > FINALLY:

    >

    > Sooooooo, Which is right 11

    > gpm or 4.3 gpm?

    >

    > The 11 gpm is the most correct

    > figure in most every instance:

    >

    > With simple

    > control (on-off circulator): You need this

    > amount of flow so that you put enough BTUs in the

    > rads OFTEN ENOUGH to liberate enough heat at

    > design. Remember that flow restriction is

    > virtually non-existant in these systems thus the

    > "downsizing" of the mains at the boiler and the

    > high flow/low head circulator. As long as the

    > velocity is not so high as to prevent any BTUs

    > from getting off in the rads, you won't have a

    > problem. If this only happens on an occasional

    > rad (likely ones closest to the boiler) you can

    > "fix" it by going back to the restrictor plates.

    > Remember that you likely have a bypass line

    > installed around the boiler anyway so a good

    > chunk of flow never makes it to the rads to begin

    > with.

    >

    > If you get the idea that you could

    > eliminate the bypass by using a smaller

    > circulator--thus trying to make it flow the way

    > it did under gravity--watch out. You'll wind up

    > with extraordinarily high delta t--particularly

    > during mild weather.

    >

    > If you now think "I'm

    > using a condensing boiler so I don't have to

    > worry about return temp" think again. That

    > careful balance of velocity in the gravity system

    > DOES NOT WORK when you add forced circulation.

    > Instead of the radiators "pulling" the water

    > through the boiler, the circulator is now

    > "pushing" the water through the rads. Since the

    > circulator is now the only source of this motive

    > power, its energy is expended in the EASIEST way

    > possible--the path of least resistance--NOT the

    > path through all the radiators. While every

    > molecule of water may be moving simultaneously,

    > they WON'T be moving at the same velocity as they

    > did under gravity. About your ONLY prayer of

    > getting this to work would be with a single-floor

    > reverse-return piping arrangement.

    >

    > With

    > constant circulation, TRVs, normal boiler: You

    > wind up with the problem just

    > mentioned--incredible delta t. You also have to

    > build enough head pressure to keep the TRVs

    > functioning so you still need the ability for

    > high flow--you just need even more bypass around

    > the boiler much of the time.

    >

    > With a

    > proportionally fired condensing boiler, constant

    > circulation and TRVs things can change. While

    > they won't have large enough tappings to operate

    > under gravity circulation, this should be

    > possible: If you could somehow vary the velocity

    > of water directly with the burner, your flow

    > could be reduced immensely most of the time. The

    > TRVs will even the velocity for you by adding

    > restriction as needed. I have no idea though if

    > the reduced electric consumption would be worth

    > the much greater complexity--I sort of doubt

    > it...



  • Boilerpro
    Boilerpro Member Posts: 410
    Verrry Interesting...

    You brought up a good point about the delta tee changing with the load on the system. However. I'm not so sure about the idea that the delta tee is huge in warmer weather on a pumped system. This does seem to be the case with a strictly gravity system, though. The sonstant and high flow of cold water going into the heating plant keeps the supply really cool. If you are running 11 gpm at 20F delta tee, you need a 110,000 btu/hr to maintain this temp difference. If you are running a 60F delta tee at 11 gpm, you need a 330,000 btu/hr to maintain this delta tee. Using the 500 edr load, you would only have about 80,000 btu/hr available (assuming th rare instatnce wher the boiler is sized properly). I don't see any way you can get the delta tee up higher unless you slow the pump.
    Also, Mike, you said the converted system would act more like a steam system, very large temp fluctuations in the rads. I just haven't found this to be true. The sheer mass of iron, steel and especially water in these systems prevents that. On a system I converted a few years ago, where the heat load was very close to the radiation capacity and the boiler was sized to the heat load, the radiators typically only changed about 20F on a typical (20F) winter day from the start of the 20 minute long firing cycle to the end. Hadn't thought about the variation in flow through a gravity system at canging water temps... wa thinking only at design. Thanks for bringing me back to the fact that all systems are dynamic, forget that for a moment!


    Boilerpro
  • Paul Pollets
    Paul Pollets Member Posts: 3,656
    Gravity Conversions and pumps

    I prefer water lubricated circ pumps. I've used a 15-42 Grundfos for small systems 26-64 for larger and have used a 26-99 for one conversion with 30 radiators and 4" mains. It's wise to put TRV's on the radiators to balance the system and install a pressure bypass differential (Danfoss AVDO) around the pump. The PBD will also reduce the pumps head if it's too large. Leaving the radiators uncontrolled after the conversion usually results in callbacks and balance complaints.

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  • Boilerpro
    Boilerpro Member Posts: 410
    Those small returns really help..

    did the same thing in two structures....but used 1/8 inch pipe nipple out of the old steam air vent opening for returns. Only letting a little water in each rad helps balance everything. No big "short circuits" for water.


    Boilerpro
  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928
    YOU'RE RIGHT

    I exaggerated and may well have goofed the delta t difference in some cases. Most of my good measurements have come AFTER my TRVs and bypass were installed and that tends to really skew the results. AND most all of the measurements have been on my system with the double-size (at best) boiler and radiation that varies from 2x oversized to nearly 4x (only one fortunately and most is about 2½ times).

    I was also looking at the gravity system as one in constant operation by virtue of the constant fire--still operating with solid fuel--not considering the "cold start" when delta t WOULD be UTTERLY massive.

    Oppositely I was considering the type of "conversion" I see most--older cast iron boiler of high water content when the boiler always heats to high limit (RARELY reset) and the circulator is controlled by the t-stat. In that case, the delta t really does act as I described--highest in moderate weather dropping as it gets colder outside.

    If you consider a much more modern boiler installation though it has LOTS of bypass in order to keep the return temp AT THE BOILER above 140 degrees. BUT the return temp from the system is MUCH lower. This is my goof, because I was considering the delta t as the difference in the temp AT THE BOILER with the difference in the return BEFORE the bypass. I probably should have kept both references on the one side or another of the bypass. Or should I? Am not certain.

    "On a system I converted a few years ago, where the heat load was very close to the radiation capacity and the boiler was sized to the heat load, the radiators typically only changed about 20F on a typical (20F) winter day from the start of the 20 minute long firing cycle to the end."

    I'M NOT TRYING TO BE DIFFICULT AT ALL BY SAYING THIS BUT if the system were still operating with a perfect coal fire (or other continuous proportional fire) the temp of the rad wouldn't have changed at all and the delta t would remain constant. If you put that 20° in terms of the assumed delta t of 20° it gets pretty big...

    "I don't see any way you can get the delta tee up higher unless you slow the pump." You CAN'T as long as the fire is EXACTLY SUITED TO THE HEAT LOSS. With an on-off fire though you can get a higher delta t given the same velocity (pump speed). It happens only when you raise the temperature of the space itself--it then decreases somewhat as the temperature of the space cools. (At least I think that's right.) When raising the temp you increase convection which speeds heat transfer. Think of the whopping delta t you can get across a window rad... In this way a proportional burner is demonstrably more efficient as it strives only to MAINTAIN temperature--not change it. TRVs do this as well, but only at the radiator--not the fire itself.

    Am currently working on reading (and understanding as best I can) the book "Maxwell's Demon" that someone recommended here. GREAT stuff. That impossible demon explains why it would take some reduced (and finite) amount of energy to exactly maintain the temp of a space than to maintain the exact same average temperature...

  • Boilerpro
    Boilerpro Member Posts: 410
    Those 1/2 inch returns really help

    They prevent the big "short circuits" that occur with regular gravity conversions. I did the same thing, but with 1/8 inch pipe nipples for returns installed where the steam air vents were on the rads.

    Boilerpro
  • Steamhead
    Steamhead Member Posts: 16,710
    I actually get about 15 GPM

    from the 005. That's a bit more than the calculations on which the chart is based would indicate but it still works much better than the 30-GPM B&G 100 did.

    That "50% bigger" rule came from B&G's 1940 Handbook. The actual method used in the Handbook was to calculate the circ size and then use the next size larger circ. Based on the circs B&G was making at that time, the "next size" would give about 50% more capacity, give or take. Taco had a similar procedure. The reason I express it that way in the chart is because B&G and Taco aren't the only ones making circs these days, so this allows you to go straight to the performance curves of whoever's circs you're using.

    BTW, everything I've read on gravity conversions says to choose the circ's capacity at a 3-1/2-foot head. This is because there's so little resistance in old gravity pipes. Most of the resistance on a conversion is probably in the near-boiler piping!

    Swampeast Mike T. hit it right on the head with his Delta-T post. This is what got me started down the circ-sizing path. If the water is moving too fast, the heat is not being picked up properly in the boiler or released in the rads. This will show up as a very small Delta-T. We want to try to mimic the flow that would occur with a gravity boiler at 180 degrees.

    In any case, I would not have sent the chart to Dan without having tried it myself on several different-sized systems. It worked so well at my house that I was able to slightly down-fire my boiler!

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  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928
    FINALLY found the BIG problem...

    ...that made you say, "how can you increase delta t without decreasing flow?" That previous WASN'T what you were talking about!!!!!

    "You have to keep the velocity (flow) up to ensure enough BTUs can make their way to the room."

    Should be "You have to keep the velocity (flow) up to ensure enough BTUs can make their way to the HIGHEST, FARTHEST rad." ...this radiator will have the highest delta t (lowest velocity) in the FORCED system.

    AND "You need this amount of flow so that you can put enough BTUs in the rads often enough to liberate enough heat at design."

    Should be "You need this amount of flow so that you can put enough BTUs in the LOWEST CLOSEST rad often enough to liberate enough heat at design." ...this rad will have the lowest delta t (highest velocity) in the FORCED system.

    SORRY!!!! I FORGOT THE DYNAMICS MYSELF AT THAT POINT!! You ALWAYS have to remember that many of the dynamics in a gravity system under natural flow are ESSENTIALLY OPPOSITE when you introduce forced flow.


  • Boilerpro
    Boilerpro Member Posts: 410
    Got to admit it does get confusing....

    I think I am going to need to ponder these things some more...starting to get cross eyed. Hope Steamhead will weight in on this topic too.

    Boilerpro
  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928
    EXACTLY

    I REALLY liked that idea when you presented it a few months ago.

    But that's a steam conversion...not a gravity conversion of course.

    Something tells me that if you wanted to put a restrictor plate (with just the right size hole) in EVERY rad on a gravity conversion that you COULD decrease the flow rate considerably...

    Talk about going cross-eyed!
  • Boilerpro
    Boilerpro Member Posts: 410
    Say, Steamhead

    Here's the issue that is confusing me. A gravity boiler at 180 degrees is probably running about 30 to 40 delta T. About double that of a modern system. This means that the flow rate through the gravity system is approaching ONLY 1/2 THE FLOW OF A MODERN 20F DELTA TEE SYSTEM. However, by sizing the circ to 50% bigger than a new system WE ARE REDUCING THE DELTA TEE TO ONLY 15, NOT INCREASING IT TO 30 OR 40. A bigger circ is going to make the system run less like it originally was, so we are not mimicing the original flow at all. Am I off my rocker?

    Boilerpro
  • Nobby
    Nobby Member Posts: 20


    Hmm very interesting enjoyable discussion and a topic that has been on my mind as of late.
    My 1880's house has as a very poorly converted gravity system still using the original piping new boiler, with items such as woefully inadequate expansion tank (4 gallons, being changed next week), circulator on return side to list 2 issues.
    Well circulator size was my recent consideration. Right now I am running on a Taco 007 which seems fine and matches Steamheads table. Balancing was won in the following way. Firstly I split the house into two zones. The old system has two return/feeds which split the house down the middle equally conveniently North/South.
    I placed the thermostats downstairs accordingly. I then proceeded after repacking the rad. valves (which hadn't moved in years) to balance the system by adjusting the valves. Now I fully appreciate that this is very possibly not a contractor solution due to the need for a period of 'fine tuning'/callback.
    The zoneing would ease balancing by reducing the amounts to deal with in by half(and also make my cold North Side warmer:). I rough balanced the system by letting the system cool of completely and then one zone at a time run it and run around the house like a blue-arsed fly constantly feeling feed pipe temperatures and adjusting valves accordingly. I also marked the valves to aid in this.
    The interesting thing is that I was suprised in that the rough balancing was fairly close to the final result. Some tweaking has since occured but I am finding the need to resist fiddleing to much.
    I am replumbing the kitchen and am piping this with two pipe reverse return(new zone) using old rads, to see how much this self balances.
    I should add that my profession is that of a Marine Engineer on older vessels so that constanyly monitoring and adjusting various fluid piping systems is part of the deal for me. I even kept a basic log of my Rad. Valve adjustments.
    Now I appreciate that my fine tuning is over the top but I am curious as to the validity for a contractor to rough tune a system by allowing complete cool down as aforementioned? The thing is it is not a simple case of saying to the HO oh just turn the offending rad. up or down if needed as it will have a knock-on effect. Also the valve turning is pretty much a matter of a couple of degrees sometimes to make a difference. One ship I worked on had a gravity system running of a furnace that used the fuel bowl carburetor forced draft setup. The furnace was always on with very little automation i.e I usually turned up or down the carburetor manually to adjust water temp. setting accordingly. The common complaint though was on the nights when the weather improved someone would turn their rad. off the next thing I new was a very hot and bothered crew member from the next cabin whose cabin had become quite the mouldy old sauna. :)
    My latest plan is Outdoor Reset when the next paycheck rolls in.
  • Nobby
    Nobby Member Posts: 20


    Hmm very interesting enjoyable discussion and a topic that has been on my mind as of late.
    My 1880's house has as a very poorly converted gravity system still using the original piping new boiler, with items such as woefully inadequate expansion tank (4 gallons, being changed next week), circulator on return side to list 2 issues.

    Well circulator size was my recent consideration. Right now I am running on a Taco 007 which seems fine and matches Steamheads table. Balancing was won in the following way. Firstly I split the house into two zones. The old system has two return/feeds which split the house down the middle equally conveniently North/South.
    I placed the thermostats downstairs accordingly. I then proceeded after repacking the rad. valves (which hadn't moved in years) to balance the system by adjusting the valves. Now I fully appreciate that this is very possibly not a contractor solution due to the need for a period of 'fine tuning'/callback.
    The zoneing would ease balancing by reducing the amounts to deal with in by half(and also make my cold North Side warmer:). I rough balanced the system by letting the system cool of completely and then one zone at a time run it and run around the house like a blue-arsed fly constantly feeling feed pipe temperatures and adjusting valves accordingly. I also marked the valves to aid in this.

    The interesting thing is that I was suprised in that the rough balancing was fairly close to the final result. Some tweaking has since occured but I am finding the need to resist fiddleing to much.
    I am replumbing the kitchen and am piping this with two pipe reverse return(new zone) using old rads, to see how much this self balances.
    I should add that my profession is that of a Marine Engineer on older vessels so that constanyly monitoring and adjusting various fluid piping systems is part of the deal for me. I even kept a basic log of my Rad. Valve adjustments.
    Now I appreciate that my fine tuning is over the top but I am curious as to the validity for a contractor to rough tune a system by allowing complete cool down as aforementioned? The thing is it is not a simple case of saying to the HO oh just turn the offending rad. up or down if needed as it will have a knock-on effect. Also the valve turning is pretty much a matter of a couple of degrees sometimes to make a difference. One ship I worked on had a gravity system running of a furnace that used the fuel bowl carburetor forced draft setup. The furnace was always on with very little automation i.e I usually turned up or down the carburetor manually to adjust water temp. setting accordingly. The common complaint though was on the nights when the weather improved someone would turn their rad. off the next thing I new was a very hot and bothered crew member from the next cabin whose cabin had become quite the mouldy old sauna. :)

    My latest plan is Outdoor Reset when the next paycheck rolls in.
  • Nobby
    Nobby Member Posts: 20


    Hmm very interesting enjoyable discussion and a topic that has been on my mind as of late.
    My 1900's house has as a very poorly converted gravity system still using the original piping new boiler, with items such as woefully inadequate expansion tank (4 gallons, being changed next week), circulator on return side to list 2 issues.

    Well circulator size was my recent consideration. Right now I am running on a Taco 007 which seems fine and matches Steamheads table. Balancing was won in the following way. Firstly I split the house into two zones. The old system has two return/feeds which split the house down the middle equally conveniently North/South.
    I placed the thermostats downstairs accordingly. I then proceeded after repacking the rad. valves (which hadn't moved in years) to balance the system by adjusting the valves. Now I fully appreciate that this is very possibly not a contractor solution due to the need for a period of 'fine tuning'/callback.
    The zoneing would ease balancing by reducing the amounts to deal with in by half(and also make my cold North Side warmer:). I rough balanced the system by letting the system cool of completely and then one zone at a time run it and run around the house like a blue-arsed fly constantly feeling feed pipe temperatures and adjusting valves accordingly. I also marked the valves to aid in this.

    The interesting thing is that I was suprised in that the rough balancing was fairly close to the final result. Some tweaking has since occured but I am finding the need to resist fiddleing to much.
    I am replumbing the kitchen and am piping this with two pipe reverse return(new zone) using old rads, to see how much this self balances.
    I should add that my profession is that of a Marine Engineer on older vessels so that constanyly monitoring and adjusting various fluid piping systems is part of the deal for me. I even kept a basic log of my Rad. Valve adjustments.
    Now I appreciate that my fine tuning is over the top but I am curious as to the validity for a contractor to rough tune a system by allowing complete cool down as aforementioned? The thing is it is not a simple case of saying to the HO oh just turn the offending rad. up or down if needed as it will have a knock-on effect. Also the valve turning is pretty much a matter of a couple of degrees sometimes to make a difference. One ship I worked on had a gravity system running of a furnace that used the fuel bowl carburetor forced draft setup. The furnace was always on with very little automation i.e I usually turned up or down the carburetor manually to adjust water temp. setting accordingly. The common complaint though was on the nights when the weather improved someone would turn their rad. off the next thing I new was a very hot and bothered crew member from the next cabin whose cabin had become quite the mouldy old sauna. :)

    My latest plan is Outdoor Reset when the next paycheck rolls in.
  • Nobby
    Nobby Member Posts: 20


    Hmm very interesting enjoyable discussion and a topic that has been on my mind as of late.
    My 1900's house has as a very poorly converted gravity system still using the original piping new boiler, with items such as woefully inadequate expansion tank (4 gallons, being changed next week), circulator on return side to list 2 issues.

    Well circulator size was my recent consideration. Right now I am running on a Taco 007 which seems fine and matches Steamheads table. Balancing was won in the following way. Firstly I split the house into two zones. The old system has two return/feeds which split the house down the middle equally conveniently North/South.
    I placed the thermostats downstairs accordingly. I then proceeded after repacking the rad. valves (which hadn't moved in years) to balance the system by adjusting the valves. Now I fully appreciate that this is very possibly not a contractor solution due to the need for a period of 'fine tuning'/callback.
    The zoneing would ease balancing by reducing the amounts to deal with in by half(and also make my cold North Side warmer:). I rough balanced the system by letting the system cool of completely and then one zone at a time run it and run around the house like a blue-arsed fly constantly feeling feed pipe temperatures and adjusting valves accordingly. I also marked the valves to aid in this.

    The interesting thing is that I was suprised in that the rough balancing was fairly close to the final result. Some tweaking has since occured but I am finding the need to resist fiddleing to much. I should also add that it still behaves balanced when both zones are on, I was lucky in that I was able to split the system fairly equally with fairly comparable lengths of run, # of rad. etc.
    I am replumbing the kitchen and am piping this with two pipe reverse return(new zone) using old rads, to see how much this self balances.
    I should add that my profession is that of a Marine Engineer on older vessels so that constanyly monitoring and adjusting various fluid piping systems is part of the deal for me. I even kept a basic log of my Rad. Valve adjustments.
    Now I appreciate that my fine tuning is over the top but I am curious as to the validity for a contractor to rough tune a system by allowing complete cool down as aforementioned? The thing is it is not a simple case of saying to the HO oh just turn the offending rad. up or down if needed as it will have a knock-on effect. Also the valve turning is pretty much a matter of a couple of degrees sometimes to make a difference. One ship I worked on had a gravity system running of a furnace that used the fuel bowl carburetor forced draft setup. The furnace was always on with very little automation i.e I usually turned up or down the carburetor manually to adjust water temp. setting accordingly. The common complaint though was on the nights when the weather improved someone would turn their rad. off the next thing I new was a very hot and bothered crew member from the next cabin whose cabin had become quite the mouldy old sauna. :)

    My latest plan is Outdoor Reset when the next paycheck rolls in.
  • Nobby
    Nobby Member Posts: 20


    Hmm very interesting enjoyable discussion and a topic that has been on my mind as of late.
    My 1900's house has as a very poorly converted gravity system still using the original piping new boiler, with items such as woefully inadequate expansion tank (4 gallons, being changed next week), circulator on return side to list 2 issues.

    Well circulator size was my recent consideration. Right now I am running on a single Taco 007 which seems fine and matches Steamheads table. Balancing was won in the following way. Firstly I split the house into two zones. The old system has two return/feeds which split the house down the middle equally conveniently North/South.
    I placed the thermostats downstairs accordingly. I then proceeded after repacking the rad. valves (which hadn't moved in years) to balance the system by adjusting the valves. Now I fully appreciate that this is very possibly not a contractor solution due to the need for a period of 'fine tuning'/callback.
    The zoneing would ease balancing by reducing the amounts to deal with in by half(and also make my cold North Side warmer:). I rough balanced the system by letting the system cool of completely and then one zone at a time run it and run around the house like a blue-arsed fly constantly feeling feed pipe temperatures and adjusting valves accordingly. I also marked the valves to aid in this.

    The interesting thing is that I was suprised in that the rough balancing was fairly close to the final result. Some tweaking has since occured but I am finding the need to resist fiddleing to much. I should also add that it still behaves balanced when both zones are on, I was lucky in that I was able to split the system fairly equally with fairly comparable lengths of run, # of rad. etc.
    I am replumbing the kitchen and am piping this with two pipe reverse return(new zone) using old rads, to see how much this self balances.
    I should add that my profession is that of a Marine Engineer on older vessels so that constantly monitoring and adjusting various fluid piping systems is part of the deal for me. I even kept a basic log of my Rad. Valve adjustments.
    Now I appreciate that my fine tuning is over the top but I am curious as to the validity for a contractor to rough tune a system by allowing complete cool down as aforementioned? The thing is it is not a simple case of saying to the HO oh just turn the offending rad. up or down if needed as it will have a knock-on effect. Also the valve turning is pretty much a matter of a couple of degrees sometimes to make a difference. Now TRV's nice idea cannot bear the thought right now of breaking apart all that piping though. One ship I worked on had a gravity system running on an old furnace (anyone heard of PYRO Scandinavian marine boiler firm?) that used the fuel bowl carburetor forced draft setup. The furnace was always on with very little automation i.e I usually turned up or down the carburetor manually to adjust water temp. setting accordingly. The common complaint though was on the nights when the weather improved someone would turn their rad. off the next thing I knew was a very hot and bothered crew member from the next cabin whose cabin had become quite the mouldy old sauna. :)

    Is there a science to the use of restriction plates or is it trial and error seems to me a PITA to have to change them out if you don't get it right.

    My latest plan is Outdoor Reset when the next paycheck rolls in.
  • Nobby
    Nobby Member Posts: 20


    Hmm very interesting enjoyable discussion and a topic that has been on my mind as of late.
    My 1900's house has as a very poorly converted gravity system still using the original piping new boiler, with items such as woefully inadequate expansion tank (4 gallons, being changed next week), circulator on return side to list 2 issues.

    Well circulator size was my recent consideration. Right now I am running on a single Taco 007 which seems fine and matches Steamheads table. Balancing was won in the following way. Firstly I split the house into two zones. The old system has two return/feeds which split the house down the middle equally conveniently North/South.
    I placed the thermostats downstairs accordingly. I then proceeded after repacking the rad. valves (which hadn't moved in years) to balance the system by adjusting the valves. Now I fully appreciate that this is very possibly not a contractor solution due to the need for a period of 'fine tuning'/callback.
    The zoneing would ease balancing by reducing the amounts to deal with in by half(and also make my cold North Side warmer:). I rough balanced the system by letting the system cool of completely and then one zone at a time run it and run around the house like a blue-arsed fly constantly feeling feed pipe temperatures and adjusting valves accordingly. I also marked the valves to aid in this.

    The interesting thing is that I was suprised in that the rough balancing was fairly close to the final result. Some tweaking has since occured but I am finding the need to resist fiddleing to much. I should also add that it still behaves balanced when both zones are on, I was lucky in that I was able to split the system fairly equally with fairly comparable lengths of run, # of rad. etc.
    I am replumbing the kitchen and am piping this with two pipe reverse return(new zone) using old rads, to see how much this self balances.
    I should add that my profession is that of a Marine Engineer on older vessels so that constantly monitoring and adjusting various fluid piping systems is part of the deal for me. I even kept a basic log of my Rad. Valve adjustments.
    Now I appreciate that my fine tuning is over the top but I am curious as to the validity for a contractor to rough tune a system by allowing complete cool down as aforementioned? The thing is it is not a simple case of saying to the HO oh just turn the offending rad. up or down if needed as it will have a knock-on effect. Also the valve turning is pretty much a matter of a couple of degrees sometimes to make a difference. Now TRV's nice idea cannot bear the thought right now of breaking apart all that piping though. One ship I worked on had a gravity system running on an old furnace (anyone heard of PYRO Scandinavian marine boiler firm?) that used the fuel bowl carburetor forced draft setup. The furnace was always on with very little automation i.e I usually turned up or down the carburetor manually to adjust water temp. setting accordingly. The common complaint though was on the nights when the weather improved someone would turn their rad. off the next thing I knew was a very hot and bothered crew member from the next cabin whose cabin had become quite the mouldy old sauna. :)

    Is there a science to the use of restriction plates or is it trial and error seems to me a PITA to have to change them out if you don't get it right.
    Any reason why adjusting rad. valves is bad I cannot immediatly think of a reason.

    My latest plan is Outdoor Reset when the next paycheck rolls in.
  • Nobby
    Nobby Member Posts: 20


    Hmm very interesting enjoyable discussion and a topic that has been on my mind as of late.
    My 1900's house has as a very poorly converted gravity system still using the original piping new boiler, with items such as woefully inadequate expansion tank (4 gallons, being changed next week), circulator on return side to list 2 issues.

    Well circulator size was my recent consideration. Right now I am running on a single Taco 007 which seems fine and matches Steamheads table. Balancing was won in the following way. Firstly I split the house into two zones. The old system has two return/feeds which split the house down the middle equally conveniently North/South.
    I placed the thermostats downstairs accordingly. I then proceeded after repacking the rad. valves (which hadn't moved in years) to balance the system by adjusting the valves. Now I fully appreciate that this is very possibly not a contractor solution due to the need for a period of 'fine tuning'/callback.
    The zoneing would ease balancing by reducing the amounts to deal with in by half(and also make my cold North Side warmer:). I rough balanced the system by letting the system cool of completely and then one zone at a time run it and run around the house like a blue-arsed fly constantly feeling feed pipe temperatures and adjusting valves accordingly. I also marked the valves to aid in this.

    The interesting thing is that I was suprised in that the rough balancing was fairly close to the final result. Some tweaking has since occured but I am finding the need to resist fiddleing to much. I should also add that it still behaves balanced when both zones are on, I was lucky in that I was able to split the system fairly equally with fairly comparable lengths of run, # of rad. etc.
    I am replumbing the kitchen and am piping this with two pipe reverse return(new zone) using old rads, to see how much this self balances.
    I should add that my profession is that of a Marine Engineer on older vessels so that constantly monitoring and adjusting various fluid piping systems is part of the deal for me. I even kept a basic log of my Rad. Valve adjustments.
    Now I appreciate that my fine tuning is over the top but I am curious as to the validity for a contractor to rough tune a system by allowing complete cool down as aforementioned? The thing is it is not a simple case of saying to the HO oh just turn the offending rad. up or down if needed as it will have a knock-on effect. Plus the danger of inadvertantly turning valves off. Also the valve turning is pretty much a matter of a couple of degrees sometimes to make a difference. Now TRV's nice idea cannot bear the thought right now of breaking apart all that piping though. One ship I worked on had a gravity system running on an old furnace (anyone heard of PYRO Scandinavian marine boiler firm?) that used the fuel bowl carburetor forced draft setup. The furnace was always on with very little automation i.e I usually turned up or down the carburetor manually to adjust water temp. setting accordingly. The common complaint though was on the nights when the weather improved someone would turn their rad. down the next thing I knew was a very hot and bothered crew member from the next cabin whose cabin had become quite the mouldy old sauna. :)

    Is there a science to the use of restriction plates or is it trial and error seems to me a PITA to have to change them out if you don't get it right.

    My latest plan is Outdoor Reset when the next paycheck rolls in.
  • Boilerpro
    Boilerpro Member Posts: 410
    Adjusting valves....

    It's great when you can turn them! When you can, you can probably get virtually any pump to work. If you really want to see how far you can go and save a little on you electric bill, you may want to try downsizing the pump some more and allowing the delta tee to increase. with those great big pipes it only takes a few watts of power to move that water. You may want to try for that 4 gpm instead of that 11 gpm in my example. BE curious to see how its works. Can't mess with my own converted gravity system, because it no longer is....I've repiped it with new smaller copper piping during ou renovation.

    Boilerpro
  • Steamhead
    Steamhead Member Posts: 16,710
    The difference is

    you have all that water in the large pipes of a gravity system. If you size the circ strictly to the BTU load or EDR, the system will be sluggish. You have to move the water fast enough, but not too fast.

    To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"
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    Steam, Vapor & Hot-Water Heating Specialists
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    Consulting
  • Boilerpro
    Boilerpro Member Posts: 410
    Sluggish

    Decribes the operation of all the gravity systms I've seen, both pumped and not pumped. So we really aren't trying to mimic the original operation of a gravity system. Hope to get a chance to toy with this on some system, maybe my neighbor will let me. Steamhead, have you tried to run your system at the 4 gpm level? I would imagine it would respond only slightly slower because it has to warm up all that water in the supply pipes first, but once going, a btu is a btu delivered at the rad, whether running only 15 delta T with 11 gpm or 40 delta tee at 4 gpm. I do agree that there are alot of overpumped coverted graivty systems. I've pulled out a few 1/6 HP 2 inch pumps in put in NRF-22's. Just wondering if we can go back to the orignal flow rates.....more or less in view of what Mike posted about the variable lfow rates these systems probably used to have.

    Boilerpro
  • Steamhead
    Steamhead Member Posts: 16,710
    Interesting idea

    but I'd need to locate a circ with a lower delivery rate than the 005, that would fit standard mounting flanges. Part of the "test-bed" idea is easily swapping components in and out so I can see the effect, and change it back quickly if it doesn't work as well. The 006 has a lower rate as does the 003, but they have sweat connections and I'd have to do some repiping. Maybe when I get some time....

    Most of the gravity systems I've seen really got going as the boiler temp reached 160 or so. Trouble is, on mild days they don't get nearly that warm and circulation suffers. If we can provide that 160-or-over rate of circulation all the time no matter how hot the boiler is, we should be fine. I think it's OK if we go slightly over, but not so much as to get a diminished delta-T.

    To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"
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    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • Boilerpro
    Boilerpro Member Posts: 410
    Why not just add a flow meter

    to your existing pump and throttle it with a valve? No need to change the pump, until you find out where you wnat to be. Just thinking out loud.

    Boilerpro
  • Steamhead
    Steamhead Member Posts: 16,710
    Good idea

    but I've never used one- any out there that you like?

    To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • Boilerpro
    Boilerpro Member Posts: 410
    Haven't used any yet

    But I think there's plenty of other folks around here that can steer you in the right direction.

    Boilerpro
  • Steamhead
    Steamhead Member Posts: 16,710
    Another reason the Dead Men oversized those boilers

    was to provide a bigger grate and firebox so the owner would not have to shovel coal so often. I see this all the time on coal-converted boilers in both hot-water and steam systems. Around here the ones I see seemed to all be sized 50-75% bigger than the radiation they served.

    When I "right-size" a circ on one of these boilers it always looks really small- but works great!

    Happy Holidays, all.

    To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"
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    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • Nobby
    Nobby Member Posts: 20


    Hmm so I have inadvertantly reduced the flow rate on my gravity system using a 007 pump. I did this by installing to small a zone valve, I had a couple of freebies so I did a suck em and see test. I do not know what it cut my flow rate down to but it was obviously slower.
    To recap I split the system into 2 zones of approx equal size corresponding to the north and south side of the house. My issues were I really had to play with the valves to balance the system I definitely experienced bad short circuiting in the rads at the beginning of the piping and I pretty much had to just barely crack the their valves to encourage flow to the rads furthest away. Warm up was really slow and the boiler was short cycling too much for my liking. I did after messing around for the whole day get it working OK enough that all rads. got warm and I didn't immediately replumb. However it was very sluggish and the balancing was really hit and miss. my rad valves are the kind that have only 180 degrees of turn from closed to fully open so that adjustments had to be really fine. I.e on the close to boiler rads. if I did anything more than just crack them they would pinch the circuit so to speak. It also seemed even more necessary to adjust the boiler temp. accordingly depending on time of year, i try to do this anyway but it just became more necessary to not forget.(outdoor reset is also on the list)
    Now granted I have no idea what flow i was getting but a gut seat of the pants based on feel estimate would be around 4gpm. As regards short cycling boiler well yes I do have approx 140000 BTU of radiation on a 185000 BTU boiler, I have yet to do heat loss calcs on the building but I do live in a basically uninsulated (not even roof insulation, its on my list) large Victorian with many large windows 58 to be exact.
    I have since changed out to bigger zone valves and things are hugely improved refer to my previous post. With all valves fully open all rads got heat without any great delays, balancing was necessary but was easy and quick to get all rooms heating nice and evenly. Now yes I probably did reduce flow a bit still but the system definitely behaved more like it used to before any of my tinkering.
    I know this is not scientific I am myself considering a flow-meter/throttling valve for the hell of it because I am really curious. I will say this my gut feeling based on intuition and experience here and other piping systems is that flow needs to be of a reasonable rate. There sure is some water in these systems and in the larger victorians some long pipe runs.
  • Boilerpro
    Boilerpro Member Posts: 410
    Steamhead, Low flow pump with standard flange

    B&G NRF-9LW, 0gpm @ 8ft., 7 gpm @ 3.5 ft, 12 gpm @ 0ft. straight line pump curve.. I am using these pretty frequently. Also using the NRF-33 : 0 gpm @ 13 FT, 20 gpm @ 7ft, 37 gpm @ 0 ft and only 125 watts. You could use two on a single tekmar to get injection rates near 70 gpm, the highest you can get with other pumps is about 45 gpm. Nice relatively flat pump curve for a wet rotor pump.

    Boilerpro
  • Glenn Harrison
    Glenn Harrison Member Posts: 405
    NRF-33 ??? for Boilerpro

    How do you like the NRF-33, especially as a replacement for the Series 100. I've been thinking about getting our supplier to stock the NRF-33 and use it instead of the Series 100.

    Try to buy B&G whenever posible to support the local economy. Also hoping they get with the program and come out with a pump to match the Grundfos Super Brute.

    Glenn Harrison Residential Service Tech

    Althoff Industries Inc. Mechanical and Electrical Contractors

    Crystal Lake, Illinois
  • Boilerpro
    Boilerpro Member Posts: 410
    NRF-33

    I've got a couple in a twinned application with eight zone valves in a church and another one as the primary circ. for one of the boilers in the same boiler room. First application and so far they are working great. Put in a pressure differential bypass around the zone valves, but it doesn't appear to be needed, even with only one 3/4 inch zone running there is no howling. It's nice that they have a less steep pump curve than most other wet rotor pumps that size and its pretty close to the 100 pump curve at 6 ft head and down. I'm moving to using zones valves due to power consumption concerns with zone pumps and the inefficiency of smaller pumps so these flatter curve pumps are pretty nice. Its looking like a pretty good maintenance free alternative to the 100, 'bout the same price too.

    Boilerpro
  • Steamhead
    Steamhead Member Posts: 16,710
    Ordered a NRF-9F/LW

    we'll see how well it works!

    But here's something else to think about: One of my test systems for the chart was an 890-square-foot converted gravity system (with O-S distributor fittings!) in a big foursquare house. This had a relatively new boiler in it with a Taco 007. Owner complained about sluggishness, and I noted that the boiler would shut off on high limit long before the thermostat was satisfied.

    The chart showed an 851-square-feet system requiring 20 GPM. This is a bit more than the 007 can produce at a 3-1/2-foot head. So I removed the 007 and installed a 0010, converting to Pumping Away also. The 0010 has a very similar curve to the B&G 100 and Taco 110 we all know and love. It will produce about 29 GPM at a 3-1/2-foot head.

    With the 0010 on the job, the system circulated perfectly- even thru the TRVs we had installed in the kitchen and bedrooms.

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  • Steamhead
    Steamhead Member Posts: 16,710
    Performance curves

    aren't identical but close. The B&G NRF-33 will pump up to 13 feet of head rather than 8 for the B&G 100 and Taco 110. The Taco 0010 pumps up to 12 feet. But in gravity-conversion applications these units are so close as to be interchangeable.

    To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"
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    Steam, Vapor & Hot-Water Heating Specialists
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    Consulting
  • Boilerpro
    Boilerpro Member Posts: 410
    Going off on high limit

    Sounds like a major short circuit in a nearby rad...or b
    the bypass piping valves not adjusted right.

    Boilerpro
  • Glenn Harrison
    Glenn Harrison Member Posts: 405
    Thanks Boilerpro and Steamhead.

    That's what I wanted to know. Will have to work on getting those NRF-33's in stock after Christmas.

    Glenn Harrison Residential Service Tech

    Althoff Industries Inc. Mechanical and Electrical Contractors

    Crystal Lake, Illinois
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