Mod Con boiler supply temps when run with baseboard or radiators

bmwpowere36m3

Gordy said:

I think you should seriously consider the higher output base boards Rich suggested. jMHO. You can get by with either less base board, or same baseboard lengths with much lower AWT.

Also the radiant in the baths are a nice touch of elegance especially if tiled. It's not to late yet for a sandwich install.

Was planning on electric in the bath, just to heat the tiles (take the edge off). Otherwise its stapling reflectors under 1" of plywood + 1" of tile/thinset/cement board. Or putting it on top of the plywood and raising it another 1" or more.

Gordy

Electric is not is not a terrible option for floor warming so long as the load for the room is not solely dependent on That emitter. Over the top hydronic would be better than under floor. 1/2" ply wood for 3/8 pex 1/4" cement board, and tiles is 1" to 1 1/8". Butted up to 3/4" hardwood flooring?

bmwpowere36m3

Gordy said:

Electric is not is not a terrible option for floor warming so long as the load for the room is not solely dependent on That emitter. Over the top hydronic would be better than under floor. 1/2" ply wood for 3/8 pex 1/4" cement board, and tiles is 1" to 1 1/8". Butted up to 3/4" hardwood flooring?

Yes, butted to 3/4" hardwood, with about a 3/4" step/sill planned. Having just radiant in the bathroom increases the complexity of the system, I would think, because I'd need to run no higher than 120F I would think. While the rest of the house emitters probably need to run at higher temps.

I know the Lochnivar can be setup to have different temp loops, but then we go back to micro-zoning. The M.Bathroom is only 4,000 Btus.

Its something to think about…right now I'm racking my brain as to how to zone.

SWEI

More efficient emitters for sure. Smiths is nice, but you might also look at Myson and Runtal -- both make panel radiators in that come 12" (or even less) high.

Those zones are right at the lower limit of the WHN085 on a design day. I'd be looking at a WHN055 or even a CDN040 for that job if it were mine.

As several of us mentioned above, the thermal mass of the building is your friend. When harnessed properly (ODR with constant circulation) this provides a flywheel effect, resulting in stability and comfort on a level few have experienced.

Oh, and the eleven zones comment was intended to be humorous. You'd be surprised how many houses we see with one zone per 400 square feet - or less. If you size the emitters properly and balance the system properly, you can make do with one or two zones even on a fairly large house.

TRVs are another option for single rooms that need separate management. The beauty there is that (unlike zone valves) they provide proportional flow control, which helps greatly to reduce short cycling.

bmwpowere36m3

Rich said:

Rich said:

Slant fin sucks . Take a look at this . Use a boiler in the 40 -50 range . Use a manifold with homeruns to each emitter and use the proper piping arrangement for each based on the BTU requirement of each room .
http://www.smithsenvironmental.com/ES_HeatEdge4cBro_SM_4.pdf

Maybe you should read this post again . In this way , later you can zone however you want by adding actuators . Actually open the link and look at the baseboard . Hint ,both bedrooms on one zone may not work as you think , they have different characteristics and exposures Goldilocks . Do radiant in the bath because you can't put enough baseboard in that monster to make it comfortable , wet naked people need building science too .
How did you enter the R values for walls and such , did you layer all the wall sections ? A wall is not just insulation it is an assembly .
Buy a phoenix water heater , FPHX , 2 pumps (ecm) and an outdoor reset mixing valve and be done . It will never short cycle and you'll have no standby loss because you'll be heating the house with it . Looking qat the bb lengths you are thinking of you can use 130* water with the Smiths .

I did look at it. It would only work for me, in a home run or parallel arrangement. In series the delta T for each emitter would be too great. And I'm not a fan of how the emitters looks, I know vanity. I also don't see much feedback, reviews, suppliers that carry it.

I'm not familiar with manifold and home runs (but I assume its similar in concept to manifold and zone valves with one circulator, but without the zone control. I assume there's one thermostat in the house that controls the circulator. It calls for heat, the circulator kicks on and heat goes to all emitters throughout the house.

How to you fine tune room to room temps once the emitters are installed? Its all good when you do the calcs, figure the heat load and size the emitters. But what happens when one rooms heat loss is greater than expected? Can't bump the supply temp because all the other emitters on the loop will be affected, right?

For R values of walls/ceilings I checked the U-Factor in the S/F tools against a calculator (which factors 15% stud and 85% insulation coverage for 16oc, along with sheathing, vapor barrier, siding, drywall, etc..).

Walls: R14.3, U 0.07 (R15 insu)
Ceiling R46.4, U 0.022 (R19+R30 insu)

Floors: R6.7, U 0.15

Floors I didn't check, I just used the default setting in S/F tool called, "Finished floor, uninsulated, over unheated basement".

Rich_49

If the bath is its own zone you do not have to worry about mixing down for it . Use the same temp as the rest of the house , assuming it does not need hotter water . When the surface temp reaches x the thermostat will satisfy and flow will cease . No more heat . Like I said in the other post , watch the 2 bedrooms as they have different exposures and will most certainly experience different calls for heat . using the manifolds allows you the freedom to add actuators later once you figure out exactly what the building and you want . It will also allow you to dial in the flow rates for design day . Look at Sunboard radiant panels , Sunfoam in particular , 1" foam product , grooved with graphite covering , 1/4" hardiboard on top and thinset job , this for the bath .
Did you by any chance enter wall and window orientation ? This also makes a difference in many programs , not sure about the Slant Fin , never used it .
The Smoths can be piped several different ways , all which effect output , maybe you could pipe it differently for the bed rooms to achieve the lower temp you desire . Lots of choices with this quality stuff .

bmwpowere36m3

SWEI said:

More efficient emitters for sure. Smiths is nice, but you might also look at Myson and Runtal -- both make panel radiators in that come 12" (or even less) high.

Those zones are right at the lower limit of the WHN085 on a design day. I'd be looking at a WHN055 or even a CDN040 for that job if it were mine.

As several of us mentioned above, the thermal mass of the building is your friend. When harnessed properly (ODR with constant circulation) this provides a flywheel effect, resulting in stability and comfort on a level few have experienced.

Oh, and the eleven zones comment was intended to be humorous. You'd be surprised how many houses we see with one zone per 400 square feet - or less. If you size the emitters properly and balance the system properly, you can make do with one or two zones even on a fairly large house.

TRVs are another option for single rooms that need separate management. The beauty there is that (unlike zone valves) they provide proportional flow control, which helps greatly to reduce short cycling.

Say panel radiators, I assume in a home-run or parallel arrangement. On design day, what supply temp and delta T would you shoot for? Looking at some of those panel radiators I would need either very large ones or a couple of smaller ones to get a return temp 130* or less. The cost of radiators goes up quite a bit.

bmwpowere36m3

Rich said:

If the bath is its own zone you do not have to worry about mixing down for it . Use the same temp as the rest of the house , assuming it does not need hotter water . When the surface temp reaches x the thermostat will satisfy and flow will cease . No more heat . Like I said in the other post , watch the 2 bedrooms as they have different exposures and will most certainly experience different calls for heat . using the manifolds allows you the freedom to add actuators later once you figure out exactly what the building and you want . It will also allow you to dial in the flow rates for design day . Look at Sunboard radiant panels , Sunfoam in particular , 1" foam product , grooved with graphite covering , 1/4" hardiboard on top and thinset job , this for the bath .
Did you by any chance enter wall and window orientation ? This also makes a difference in many programs , not sure about the Slant Fin , never used it .
The Smoths can be piped several different ways , all which effect output , maybe you could pipe it differently for the bed rooms to achieve the lower temp you desire . Lots of choices with this quality stuff .

I used three different (free) tools and none of them account for house orientation or solar gain.

To avoid a mixing valve I would need to run radiant everywhere else in the house (unless I literally line every wall with some form of baseboard).

bmwpowere36m3

Man this all this is making my head hurt. I think designing a system with one thermostat/zone is way beyond what I can manage.

Gordy

One thing you are discovering is many ways to skin the cat. Many options. I was going to mention TRVs with home run piping that allows total control of each zone with out controls beyond the trvs. A Trv is a valve that opens proportionally to the user setpoint to maintain temp. It all boils down to budget, and getting the most with in that budget. You can spend a lot in components if not correctly done its a train wreck.

Edit: I will add that home run advantage with trvs eliminates zone valves, and associated controls. also the disadvantages of series piping with dropping average water temps through a series circuit. I only say anything about zoning is because I can tell in your readings you cant fight the urge.

Also remember we are about squeezing every bit of performance out of a system with minmal energy usage. yes the smith baseboard is not the best looking, but as i said, and why it gets used. Riches recommendation should be the only review you need.

bmwpowere36m3

Gordy said:

One thing you are discovering is many ways to skin the cat. Many options. I was going to mention TRVs with home run piping that allows total control of each zone with out controls beyond the trvs. A Trv is a valve that opens proportionally to the user setpoint to maintain temp. It all boils down to budget, and getting the most with in that budget. You can spend a lot in components if not correctly done its a train wreck.

Edit: I will add that home run advantage with trvs eliminates zone valves, and associated controls. also the disadvantages of series piping with dropping average water temps through a series circuit. I only say anything about zoning is because I can tell in your readings you cant fight the urge.

Also remember we are about squeezing every bit of performance out of a system with minmal energy usage. yes the smith baseboard is not the best looking, but as i said, and why it gets used. Riches recommendation should be the only review you need.

I agree, I guess it goes back to my fundemental desires. To maintain temps of 70F or so throughout the house, slightly higher in the bathrooms and at night setback the bedrooms only to comfortable sleeping temps.

SWEI

bmwpowere36m3 said:

How do you fine tune room to room temps once the emitters are installed?

The angle stops used on radiators have balancing valves in them. Manifolds (if you go that route) have balancing valves on them.

Series piping is tough to get right thanks to the cascading temperature drops. You'll spend even more on emitters as a result (bigger/longer ones near the end of the loop) and balancing after the fact is nearly impossible. 3-way TRV's cost more. Don't do it.

I used three different (free) tools and none of them account for house orientation or solar gain.

No real need to figure in solar gain when you do a heat loss calc. You're sizing for the coldest day or two of the year, which generally happens with little or no sunshine. You do need to take it into account when you plan your zoning and controls. Remember that a TRV can only make that room cooler, not hotter and it will start to make sense. The supply water temp has to be high enough to heat the coldest room with whatever emitter(s) are in it. The better you match the emitters to the heat loss, the less TRVs you need to buy.

Say panel radiators, I assume in a home-run or parallel arrangement. On design day, what supply temp and delta T would you shoot for? Looking at some of those panel radiators I would need either very large ones or a couple of smaller ones to get a return temp 130* or less. The cost of radiators goes up quite a bit.

Size them for the lowest temp you can afford ($$) or fit (available wall space.) Panel rads can run happily at a 30°F ΔT. Remember that for a given size (nominal output) radiators perform far better at low water temps than fin-tube does. Also watch out for a "15% heating effect" (marketing BS) included in most baseboard ratings. Once you compare apples to apples, panel rads start to look more attractive. Fancy radiators cost a LOT more than basic panel designs do. Less wall space taken up leaves more flexibility in furniture placement. Most houses have at least one room with a limited amount of space that ends up determining the sizing for the rest of the job. It's a parametric process that sometimes takes a few passes to get right.

Return temps below 130°F are a good thing, but there is more to the story than that. First, there is no there is no magic jump in efficiency the moment condensation begins. Thermal efficiency goes up as RWT goes down -- it's a continuum. Second, you are running numbers for a design day (2.5% of the time on average.) The rest of the season, ODR will set your water temp below that number.

This presentation does an excellent job of covering the bases. Their numbers show that with a design SWT of 160°F in Boston, you'll still be condensing 97% of the time. We usually end up sizing for 140-160°F on radiators and have not had any complaints.

Rich_49

130* SWT is what I figured for the house . 16.25 feet in 7475 room , 12.7' in 5840 room , 14.25' in 6560 room and 18' in 8310 room . Of course these lengths would get smaller with higher AWT . All parallel piping Kitchen wil take some doing at that temp and we cannot see where cabinets and such are in bath and kitchen , makes it harder to help . Smith with the parallel piping will only require `1 1/2 gpm also to get the output . That puts you in condensing condition 100% of the time . Radiant in bath should certainly be lower than 130*so I wouldn't see a problem there . Maybe radiant kitchen or panel rad with a TRV there .

bmwpowere36m3

Gordy said:

One thing you are discovering is many ways to skin the cat. Many options. I was going to mention TRVs with home run piping that allows total control of each zone with out controls beyond the trvs. A Trv is a valve that opens proportionally to the user setpoint to maintain temp. It all boils down to budget, and getting the most with in that budget. You can spend a lot in components if not correctly done its a train wreck.

Edit: I will add that home run advantage with trvs eliminates zone valves, and associated controls. also the disadvantages of series piping with dropping average water temps through a series circuit. I only say anything about zoning is because I can tell in your readings you cant fight the urge.

Also remember we are about squeezing every bit of performance out of a system with minmal energy usage. yes the smith baseboard is not the best looking, but as i said, and why it gets used. Riches recommendation should be the only review you need.

Is there a fundamental difference between a home-run setup (1 circ) with radiators and TRVs… vs. a separate zones (circulator or zone valve and thermostat)?

bmwpowere36m3

SWEI said:

bmwpowere36m3 said:

How do you fine tune room to room temps once the emitters are installed?

The angle stops used on radiators have balancing valves in them. Manifolds (if you go that route) have balancing valves on them.

Series piping is tough to get right thanks to the cascading temperature drops. You'll spend even more on emitters as a result (bigger/longer ones near the end of the loop) and balancing after the fact is nearly impossible. 3-way TRV's cost more. Don't do it.

I used three different (free) tools and none of them account for house orientation or solar gain.

No real need to figure in solar gain when you do a heat loss calc. You're sizing for the coldest day or two of the year, which generally happens with little or no sunshine. You do need to take it into account when you plan your zoning and controls. Remember that a TRV can only make that room cooler, not hotter and it will start to make sense. The supply water temp has to be high enough to heat the coldest room with whatever emitter(s) are in it. The better you match the emitters to the heat loss, the less TRVs you need to buy.

Say panel radiators, I assume in a home-run or parallel arrangement. On design day, what supply temp and delta T would you shoot for? Looking at some of those panel radiators I would need either very large ones or a couple of smaller ones to get a return temp 130* or less. The cost of radiators goes up quite a bit.

Size them for the lowest temp you can afford ($$) or fit (available wall space.) Panel rads can run happily at a 30°F ΔT. Remember that for a given size (nominal output) radiators perform far better at low water temps than fin-tube does. Also watch out for a "15% heating effect" (marketing BS) included in most baseboard ratings. Once you compare apples to apples, panel rads start to look more attractive. Fancy radiators cost a LOT more than basic panel designs do. Less wall space taken up leaves more flexibility in furniture placement. Most houses have at least one room with a limited amount of space that ends up determining the sizing for the rest of the job. It's a parametric process that sometimes takes a few passes to get right.

Return temps below 130°F are a good thing, but there is more to the story than that. First, there is no there is no magic jump in efficiency the moment condensation begins. Thermal efficiency goes up as RWT goes down -- it's a continuum. Second, you are running numbers for a design day (2.5% of the time on average.) The rest of the season, ODR will set your water temp below that number.

This presentation does an excellent job of covering the bases. Their numbers show that with a design SWT of 160°F in Boston, you'll still be condensing 97% of the time. We usually end up sizing for 140-160°F on radiators and have not had any complaints.

Awesome a lot of good info…. that presentation was really informative.

What delta T are you targeting when selecting radiators? The delta T and GPM kind of confuses me and more so when you take into account the boiler-side and its delta T and GPM requirements.

bio_guy

SWEI said:

Here's a description of the feature from Triangle Tube:

Boost Feature Setting
(Parameter 19)

The Boost Feature is available when a room thermostat is selected for the CH operating signal with Parameter 45 and an outdoor temperature sensor is connected to the boiler. This feature can be used to compensate for a low outdoor reset schedule or to provide a quicker morning recovery.

If a call for heat is not satisfied in the time period set by this parameter, the CH setpoint will be raised by 18°F.
The CH setpoint will continue to be raised by 18°F for each time period that the call for heat is not satisfied until the CH Maximum Boiler Operating Setpoint (Parameter 4) is reached.

Once the call for heat has ended, the CH setpoint will decrease by 2°F per minute until the original CH setpoint is reached. If a call for heat occurs while the CH setpoint is decreasing, the boiler will operate at the current CH setpoint. The Boost Feature will still be active and will raise the CH setpoint by 18°F if the call for heat in not satisfied in the time period set by this parameter.

The boiler-autonomous boost feature seems pretty slick. My continuing feeling is, however, that a more modern thermostat interacting with the boiler could work so much better. If the thermostat can talk to the boiler and tell it that a set-back recovery is in progress and the outdoor temp is known, the system can be programmed to learn what water temp will be necessary to be at a given temp at a particular time and when to start the recovery. You could even set for longer recovery with higher efficiency or shorter recovery sacrificing efficiency.

After some early heat pump missteps with set-back t-stats and people getting killed on resistance heat strip electricity use, some decent thermostats were designed. It is painful to know that the modulating boiler people can't see that a similar approach would work.

Gordy

While the boost is nice. I still believe setback, and ODR are not a good marriage. Other mod/con manufactors have similar control programing just not described for use in that way.

icesailor

Why bother.

Infiltration is the most under rated and underestimated factor in heat loss. Most are clueless as to how it works or how bad it can be. Because even if you are experiencing it, it's like CO poisoning, Silent but deadly.

Hatterasguy is a smart dude. Has lots of answers. But not to infiltration. If Cape Hatteras is anything like where I lived and worked my life and career, it regularly blows the @$$hat out of a cow. And the storms that make up where he lives, go Northeast and blow all over us. We had WInter storms that regularly blew over 70 MPH and gusted over 85 MPH. Sucks all that cold air down from Canada. Freezes the lakes on ponds. Makes for good ice sailing.

The fastest way to determine if you have an infiltration problem is if you have a system designed for -0F, and it is 12 degrees outside and there is no wind, and all the rooms are at 70 degrees with the boiler cycling off on high limit, but three days later, the wind is 20MPH to 30MPH and gusting to 40+, and the OAT is 28 degrees with the boiler cycling on and off at high limit but the building won't get over 62 degrees, you have a serious infiltration problem. If the system won't go over 165 and the high limit is set for 180 degrees, you have an infiltration problem and an undersized boiler.

It works both ways. Heating and cooling (manual J) Its called "Crackage".

Modern building codes require all sorts of ventilation. We as heating professionals, have no idea what building codes are requiring to be done for fresh air in new buildings. The former building commissioner/chief of where I lived and worked, was a Master Plumber and a licensed Marine Engineer, told me that the Massachusetts Building Code requires 17 ACH in bedrooms. Anyone figure in 17 ACH's per hour?

My 30 YO Florida Condo , of which there are 240 units, all on one floor (like houses) never had any problems cooling. Until I replaced my system with a more "Efficient" system with all new ductwork etc, they all worked fine. Once I replaced it, it wouldn't cool below 80 degrees if it was more than 98 degrees outside. Three years before, they replaced the roofs. They put full length ridge vents under the top cap. Along with the top square vents that were there before. They increased the air flow in the attic many times over. I needed more insulation in the attic. There are full length soffit vents on the overhangs. Telling the installers that their new system wouldn't cool my house was like talking to a deer in the headlights. The amount of cooling energy that was being sucked into the hot (over 140 degrees) through recessed can lights was expensive. IFC lights aren't water proof, nor are they air tight.

When something doesn't work, and it is not of your doing, you ask for help and no one is there. You either walk away and learn nothing, or you tighten your belt, get to work, and figure out what they problem is. And if it is solvable. What do you do when someone says to you "Gee, I don't know how I can help you". And they hang up. Who you gonna' call now? Not Ghostbusters. When I need help, I had to call ME.

If it is cold out and windy, take a Infra-Red thermometer gun and shoot a ceiling that is exposed to an unconditioned space (like a "properly" ventilated attic space. Shoot the ceilings, Especially along outside walls, Then, shoot the inside walls 2" down from the ceiling, If there is more than a 2 degree difference, the ceiling being colder than the room, you have a cold air infiltration/heat loss, cold gain issue. How you gonna fix it? In a 15' X 15' room, you now have a 225 square foot cold sink ceiling with the heat in the building transferring through it. (expect in Florida where I was told it is the other way around).

I could write a whole topic of the large buildings I have been to with these problems. And none of my doing. Some designed and stamped by Registered PE's.

Knowing why and how something doesn't work doesn't mean I'm mentally deficient.

icesailor

Do you understand that AHRI/IBR use 15 MPH as the normal maximum wind speed, and 3 ACH in a tight house?

You need to look at my personal example I stated that I didn't dream up. It is something that I found on numerous occasions. Easily proven by raising up the high limit. Which increased the system water temperature and increased the output of the emitters.

ced48

This one is starting to get out of control, a bit, but you've got my attention. Like lots of issues like this, people who are the most vocal seem to be at opposite ends. Both arguments have merit, but compromise is what the real world is about. Having a heating system that you turn on in October, and shut off in April, with only one ignition, isn't going to happen with todays available equipment, just to many variables and combinations of temperature, sun, and wind.

Last year, with full knowledge, I installed a Loch WH55 that was twice as big as my design day. This has proven to be right on, because I never operate over 45 percent, even on windy, design day conditions.

Does it work efficiently? Heating system always is in a condensing mode. I can't modulate any lower than 11K input, so I run 110 degree water in outdoor temps over 30 degrees, Fire 20 to 30 minute, with 35 to 45 minute off periods, for one hour plus cycles. Not perfect, but quite nice to live with. At temps below 30, I have longer run times, ORC increase by a degree per degree, but shorter off periods, but cycles still well over an hour. I am still fine tuning this, and may cut back water temperature even more, but when the wind blows 50 knots, sure is nice to feel the heat.

One major plus in having an oversized boiler that lives in the den with you, is noise. Because I operate at 20 to 40 percent, there is really very little noise. When I have run in the upper ends, the fan noise is much, much louder. This way, I can walk into the room, and not know wether the heat is on, or not-

I just think it makes more sense to design a system that will allow the owners to make their own adjustments to fit the way they live. If you figure this thing so close, there is no rome for mistakes, or style changes. I'm not suggesting 100 percent, a boiler that is maybe 20 percent above ideal design numbers, makes sense as a workable solution until we develop a system that turns on in the fall, and goes to sleep in the spring, kind of like reverse hibernation.

Gordy

If ach is underestimated then why all the oversized boilers in this country ,and why do some heat loss programs over estimate by 10-20% . Rarely have we seen anyone here complain about an undersized boiler

Just sayin

How long do you really have sustained winds of that caliber.

icesailor

Judging by some of the comments/questions here during this current cold spell and others in the past, I fear that some might not be able to tell a undersized boiler or a lack of emitters if it sprayed dirty purge air and water in their face.

bio_guy

ced48 said:

This one is starting to get out of control, a bit, but you've got my attention. Like lots of issues like this, people who are the most vocal seem to be at opposite ends. Both arguments have merit, but compromise is what the real world is about. Having a heating system that you turn on in October, and shut off in April, with only one ignition, isn't going to happen with todays available equipment, just to many variables and combinations of temperature, sun, and wind.
...
I just think it makes more sense to design a system that will allow the owners to make their own adjustments to fit the way they live. If you figure this thing so close, there is no rome for mistakes, or style changes. I'm not suggesting 100 percent, a boiler that is maybe 20 percent above ideal design numbers, makes sense as a workable solution until we develop a system that turns on in the fall, and goes to sleep in the spring, kind of like reverse hibernation.

Seeking a system that runs at max efficiency with no nod to flexibility and comfort can make one a slave to the technology rather than the other way around and for little benefit. Approaching 100% efficiency has increasing costs or diminishing returns. At some point, a reasonable person gives up and lives. Some people may want to sleep in a cooler home. Others want an area with an entertainment center to work-out on their treadmill at 62F in the morning and lounge on the couch in the evening at 72. Oops, our boiler efficiency will drop from 96% to 95.5% if we want to do that. It might cost $30 annually in a less efficient home and half that in an efficient one. On the other hand, keeping the temperature lower through most of the day can more than make that up. Setbacks save fuel even with modulating, condensing boilers. The specs that I have seen for condensing boilers indicates that they operate more efficiently at partial capacity than at full capacity which seems to be an overlooked feature. It just seems to me that controlling your indoor environmental temperature with an outdoor sensor, as much fun as it is to attempt, defies logic as a practical solution.

RobG

I believe that with todays technology the best way to match the load is with multiple small mod/cons cascading. I do realize that most people cannot afford it however the closer you can get to matching the load the less fuel you will burn, and redundancy is a huge plus. I did a job (designed by an ME) with sixteen 300K boilers (I never saw more than twelve run) they were not modulating boilers but in theory it was a 16/1 turndown. If they had been mod/con's it would have been 80/1 turndown. Talk about matching the load?

bio_guy

In fact, you would only need one modulating boiler with 15 non-modulating to get a 16/1 ratio.

bio_guy

Oops, I meant one modulating to get 80/1.

RobG

bio_guy said:

In fact, you would only need one modulating boiler with 15 non-modulating to get a 16/1 ratio.

Actually that would be a 21/1 turndown (depending on the mod/con).

bmwpowere36m3

Hatterasguy said:

This can only work in commercial or very large residential applications. How many houses need 100K (two tiny mod-cons)?

Right?

So back to reality... we are talking about a 1600 sq ft house, with a design day load of 28k BTUs/hr (not factoring in infiltration). Infiltration adds anywhere from 7 to 29k BTUs/hr (0.5 to 2 ACH).

RobG

Sorry we got off topic . I have to re-read the post to find out what it's about.

bmwpowere36m3

Gordy said:

Electric is not is not a terrible option for floor warming so long as the load for the room is not solely dependent on That emitter. Over the top hydronic would be better than under floor. 1/2" ply wood for 3/8 pex 1/4" cement board, and tiles is 1" to 1 1/8". Butted up to 3/4" hardwood flooring?

Can this "sandwich" radiant floor heating be run at 160*, which I was planning for the rest of the emitters on design day. Or will I need a mixing valve to reduce temps?

Max expected output of floor radiant (BTU/sq)? Any helpful links that I can read more on this specific heating method? Thanks.

bmwpowere36m3

Is the IBR method as per the S/F calculator good for sizing radiant panels… i.e. for example the heat loss for a room is 6k BTUs/hr, I select a steel panel radiator for 6k BTUs/hr based on desired supply temp?

Jean-David Beyer

Boost, ODR, and setback.
I have a boiler that has outdoor reset, and it can be set to boost if the boiler takes too long to re-heat the zone that was set back. I have two heating zones: upstairs (fin-tube baseboard, much longer than usual); downstairs (radiant slab at grade).

No point doing setback downstairs because it takes several days to drop 10F there (I was forced to try that when storm Sandy cut off my power for almost a week). And I never tried the boost feature there.

I did try small setback in the upstairs zone (2F setback(), and the temperature up there would drop in a couple of hours. Trouble is, the ODR curve was set so tight that I do not think it would ever recover. I set it so if it had not recovered in 2 hours, it would give a 10F boost to the supply water, and every 2 hours, it would give an additional 10F boost, until it hit the upper limit I allowed for that zone). It still did not recover very fast.

If I tried the boost on the radiant slab zone, the slab would get so hot that the overshoot would be intolerable indeed. After storm Sandy, I diddled the ODR to increase the supply temperature by 10F for a day or two to get the house back up to temperature, and then put it where it was supposed to be.

I would not want to set boost for the slab zone in any case, because the longest I can have it wait before it is applied is 4 hours, and the way I like it adjusted, it can run 18 hours straight sometimes and holding indoor temperatures within a degree of the set point. If boost were applied after 4 hours, the temperatures would wander all over the place.

For my system with ODR, setback seems a very bad idea,

Gordy

.

bmwpowere36m3 said:

Gordy said:

Electric is not is not a terrible option for floor warming so long as the load for the room is not solely dependent on That emitter. Over the top hydronic would be better than under floor. 1/2" ply wood for 3/8 pex 1/4" cement board, and tiles is 1" to 1 1/8". Butted up to 3/4" hardwood flooring?

Can this "sandwich" radiant floor heating be run at 160*, which I was planning for the rest of the emitters on design day. Or will I need a mixing valve to reduce temps?

Max expected output of floor radiant (BTU/sq)? Any helpful links that I can read more on this specific heating method? Thanks.

160 With hot mits for slippers. You need to mix down if you are running that kind of water temps. Now IF you chose the higher output baseboards Smith you might get by. Are you planning to soley heat the bath with radiant? I doubt there is sufficient floor area. Might need a towel warmer or panel rad to supplement it. Orrr staple up at those temps

bmwpowere36m3

Gordy said:

160 With hot mits for slippers. You need to mix down if you are running that kind of water temps. Now IF you chose the higher output baseboards Smith you might get by. Are you planning to soley heat the bath with radiant? I doubt there is sufficient floor area. Might need a towel warmer or panel rad to supplement it. Orrr staple up at those temps

Possibly, I figure around 84 sq ft including the shower area (large walk-in 27 sq ft).

Below is the Nu-Heat proposal for electric:


I was thinking towel warmer as well or I could do a radiant panel.

hot_rod

160- 180°F supply was common with the old Wirsbo "dangled tube" method. Also some UltraFin systems would require that high temperature.

As for floor output, about 1.7- 2 btu/ sq. ft for every degree difference between floor surface and ambient, is one rule of thumb. 2 makes the math easy.

For example a 70° room temperature with 80 floor surface = 20 btu/ sq. ft. floor output.
80°F is about as warm as you want the tile surface for bare foot comfort, above that it starts to get uncomfortable = sweaty bare feet

Suspended tube about 180F, with 70°room would get you about 20 but/ sq. ft.

Concrete slab with 12" OC spacing figure about 88- 90°F average water temp. in the loop, gets you about 15 btu/ sq. ft.

bmwpowere36m3

hot rod said:

160- 180°F supply was common with the old Wirsbo "dangled tube" method. Also some UltraFin systems would require that high temperature.

As for floor output, about 1.7- 2 btu/ sq. ft for every degree difference between floor surface and ambient, is one rule of thumb. 2 makes the math easy.

For example a 70° room temperature with 80 floor surface = 20 btu/ sq. ft. floor output.
80°F is about as warm as you want the tile surface for bare foot comfort, above that it starts to get uncomfortable = sweaty bare feet

Suspended tube about 180F, with 70°room would get you about 20 but/ sq. ft.

Concrete slab with 12" OC spacing figure about 88- 90°F average water temp. in the loop, gets you about 15 btu/ sq. ft.

How does running 3/8" PEX (o2 barrier) with heat transfer plates, 8" OC sound? Loop-length limited to 200'?

Sandwich: 1/2" plywood> 3/8" PEX & HT plates> modified thinset> 1/4 to 1/2” cement board> thinset> tile

hot_rod

That was my "go to" system for many years, 3/8 tube, extruded plates.

Some of the best output and design info on plates is at radiantengineering.com They pioneered the extruded plate design and have many years experience with the system design and performance.

In Modern Hydronic Heating fourth edition that exact system is modeled and shown via FEA in Chapter 10.

The RPA has a boatload of good info, get a copy of their Radiant Floor Covering Guide at the very least.

The key to any radiant floor design is knowing the limitations. Somewhere around mid to high 20's BTU/ sq. ft. loads it's time to look at some supplemental heat. Trying to go above that output leads to excessive floor temperatures, floor covering issues, inadequate heat output, and a black eye for the industry.

Good for you asking questions before pulling out the power tools..

Most of the un-happy radiant floor customers we hear from here are under-performing systems due to improper design.

Know the loads, calculate the heat flux, pay attention to floor covering r-value, and spend the time and money to get the best control package. Just some of my $.02

bmwpowere36m3

If I plan on radiant panels with TRVs and a pex radiant manifold… do I need bypass fittings at the radiators or can I plumb them direct to the manifold (i.e, pex directly from manifold to threaded BSP fitting in radiator)? For a circulator to run that "loop" or manifold would a Bumblebee work (dT) or do I need a Grundfos Alpha (dP)?

bmwpowere36m3

and or do I need a radiant manifold with flow setters?

What if I plan to connect a radiant floor loop to that same manifold (for the bathroom) and a towel warmer?

So four radiant panels with TRVs, 1 radiant floor loop (bath) and 1 towel warmer (same bath)?

hot_rod

With a home run system use a nice radiant manifold. The rads with TRVs pipe to the manifold, not needing actuators.

The bathroom zone I would use a dual stat that measures air and floor temperature. That wires to an actuator on the manifold.

Purchase the manifold with a couple extra ports, you may want to add additional components, towel bars, radiant art, etc.

A delta P circ would be best for this type of zoned system, a perfect match for TRV systems.