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New boiler and a few questions

Gravyfries
Gravyfries Member Posts: 19
Hello folks,

 I'm about as clueless as a homeowner can be about boilers.  My 40 year old American Standard boiler was starting to get a little long in the tooth so I decided to get it replaced.   I have an older house and decided early on that I had too much rehab work to do ($$$) so I couldn't opt for a Mod Con boiler.  I received 4 bids and went with the company that did a heat loss.  Regarding cost, they were smack dab in the middle of the bids.  The heat loss was  fairly basic but at least better than 2 of the companies that bidded on the project.   After much deliberation, I decided to go with the Burnham p205 series 2 boiler.  I  reasoned that having a simple cast iron boiler would be reliable and since I keep the place fairly cool in the winter that I personally would still have a fair amount of savings over my 60% eff boiler.  Now that I got a little background out of the way, I'd like to ask a few questions.



Since the installation, I notice that my first floor radiators are noisy.  The noise is kind of a higher pitch whirring noise that I believe is the sound of water rushing through the radiators.  It isn't a gurgling sound like some of the posts I've read, but more of a quiet roar.  It might be me but I think it has gotten a little bit louder since the installation about a month and a half ago.  What would be causing this?  I notice the bladder tank is on the opposite side from the pump. I assume that means that the boiler is not pumping away?  The contractor insisted that it be piped in black cast iron.  Actually 2 out of the 4 bids insisted that it should be cast iron. 



My other question is this:   I notice that the pressure of the boiler is fine while on but the temperature doesn't seem  very high.  I don't think I've seen it past 120 degrees.  It looks like the aquastat is set to 180 degrees.  I'm not sure if the temperature guage is reading the return water temperature.  If so, what should this temperature be?



I'll try to attach some photos.  I had a new 'short' style water heater installed which appears on the second and third pics.  Just wanted to clarify.  I really appreciate your help! 
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Comments

  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,510
    noisy flow

    have you asked your installers what they think?--nbc
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,837
    Well.....

    I must say, those are some VERY nice pictures of straight piping. Must have been raised by an old school pipe fitter that understood quality and workmanship.



    You said you've not seen the boiler above 120 degrees F. That is not good for this design of boiler. It WILL condense, and its not made to.



    One way around this problem is to install a thermostatic mixing valve that guarantees the boiler block is above 140 F before it starts releasing energy to the house.



    My assumption is that the boiler pump is pumping away from the boiler seeings as how it is on the supply line. The expansion tank SHOULD be as close to that pump as possible, but the negative consequences don't outweigh the cost of changing the piping. It causes a "droop" (not to be confused with drop) in the static system pressure between the expansion tank and the pump, but probably wouldn't cause the pump to cavitate. High head pumps and high pressure drop boilers in this scenario can cause a hummm... Hmmmmm :-)



    Noises are difficult to diagnose without actually being on site, but the things I have seen cause noise in systems is partially closed valves, too large a pump, pump with excess head (pressure) capacity, and more.



    What model of pump is one there?



    It appears that this was originally a gravity system, no?



    The pipe work is immaculate IMPO.



    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • Gravyfries
    Gravyfries Member Posts: 19
    Thanks

    Well that makes me feel good about the piping.  The company has been in business over 80 years.  Younger guys were on the job cutting and threading all of the pipe and doing the installation.   Regarding asking the installer, I wanted to have a little bit of an idea before I had them come back out. 



    After the installation the inspector noticed that the pump wasn't tightened down enough and there was a tiny water leak.  The contractor came out (it wasn't one of the installers) and he tightened up the pump.  I didn't ask about the noise at the time but I did ask about the temperature.  I thought the guage was broke since it didn't seem like it was rising.  Once he saw the guage rise, he told me it was fine.   I also told him that the radiators don't seem to get very hot.   He said that I was probably over thinking it since it was reaching my temperature of the house.  I've had folks ask me why my radiators don't get hot.  They only get warm.  If I cut the heat up and the boiler really has to work, then they do get pretty warm.  I keep the house at constant temp and don't do setbacks.



    Mark, the pump is a Taco 007.  I was told it was a former gravity system.  I always wondered why the pipes were so big.....



    Oh yeah, I had another question.  When the boiler shuts off, it goes clank!  It is pretty loud upstairs.  Definitely sounds like a metal on metal sound.  I don't know if this is normal.  I wouldn't think so.  Appreciate the help, Thanks!
  • Brad White
    Brad White Member Posts: 2,393
    Temperature

    A gravity HW system, especially one that splits into 2" or 2.5" branches as yours seems to, would easily have a pressure drop, even at 20 gpm, of 3 or 4 feet of head including the boiler and fittings. A Taco 007 would find its way to that balance point, easily in such a system with about 18 gpm in my experience.



    On your system with a 5 section Series 2, (108 MBH output), that would get you to about an 11-12 degree temperature rise across the boiler.



    (I have seen worse- when we bought our current house it had three 007's and was moving over 40 gpm through the boiler with a 3 degree rise!)



    Anyway, I would do a couple of things:

    Install a bypass to or better yet a thermostatic valve on the return to keep the block hot as Mark said.



    Slow down the circulator -one of the three-speed circulators or even one of the Delta-T circulators would be sweet. Last method I would use is a balancing valve. It will work, but it is driving with the brakes on.



    If you do any re-piping, I would move the expansion tank immediately upstream of the circulator. As Mark said, given the low overall pressure drops in the system, the connection point or rather the difference from the ideal connection point, is less critical than in systems with higher pressure drops. So it is not essential that you move it, but take the opportunity when you do re-pipe.



    As for noise, I doubt it is velocity noise in those large pipes, but it might be velocity noise in the smaller connecting piping, transmitted through the system. A small noise can travel far in essentially incompressible fluids.



    The banging noise? No idea. Pump contactor maybe? Hard to say. On light-off, there is a snapping sound sometimes, but not at the end of a cycle.
    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"



    -Ernie White, my Dad
  • heatmiser
    heatmiser Member Posts: 16
    ????

    what kind of radiation do you have??????sounds like the system is air bound. i don't understand why you would hang the expansion tank in that position. i also don't see an air scoop or spirovent to scrub the air pockets out of the system.there is absolutely no reson why the boiler shouldn,t go past 120 deg. there is something wrong!!!!!get your contractors back out there.
  • Mike Kusiak_2
    Mike Kusiak_2 Member Posts: 604
    System temperature

    The reason that the boiler temperature normally remains below 120F is because that is all that's necessary to meet the building's heat load. He has a converted gravity system with huge cast iron radiators. So he is effectively overradiated for the current building heat loss and can satisfy the thermostat with very low water temperatures. The water temperature will go higher if necessary, but in a high mass system like this, the water temperature averages out to the level necessary to meet the load. It's kind of like outdoor reset, the water temperature only reaches the temperature required to satisfy the thermostat and heat loss.
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,837
    Bottom fill, top vent...

    Miser, when dealing with a space heating only, high mass, large volume standing cast iron radiation system, it is not necessary to have the usual air removal devices on the near boiler piping. Its a waste of time and money.



    You fill the system from the bottom, and manually vent the air out of the top at all radiators. Once completely vented, any micro bubbles will come out of suspension in the upper chambers of the radiators where it won't do any harm.





    This IS your grandpas heating system....



    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • Jamie Hall
    Jamie Hall Member Posts: 17,095
    Another thought...

    on the noise.  If it is more like a whine (a more or less definite, more or less constant pitch rather than a hiss or a whish) it just may be the pump itself, telegraphing through the piping.  I have seen that (or, rather, heard that!) happen, and it can be difficult to get rid of.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Gravyfries
    Gravyfries Member Posts: 19
    Condensation?

    Jamie, yes I'd say it is a whine.  It definitely sounds louder upstairs than it does downstairs.  My old system had a B&G oil pump that didn't make this noise.  Also if you look at the picture with the PBR sign, you'll see a half circle cut out at the top of the picture.  That was where the old steel expansion tank was located.  I almost wish they didn't replace it.



    Now that I've talked to you guys, I think I really need to focus on that temperature.   I got this boiler hoping to have reliability but now I'm afraid of it condensing.  I assume it is the heat exchanger condensing?  I've never seen any condensation outside the boiler.  It irks me that they never checked the temperature guage and when I brought it up they told me it was fine.  It would seem that checking something so simple would save huge headaches for the both of us down the road, especially after going through such lengths to put in cast iron piping.  I'll have to ask them about the thermostat mixing valve.  That sounds like a great idea.  When I checked the temperature this morning it was 110 degrees immediately afterr the boiler switched off.   I have a question, though.  If this valve gets installed, will the boiler keep heating up the water until it hits the proper temperature?  If so, will it make the radiators warmer since it is forcing the boiler to stay on longer?  Sorry for the confusion. 



    Ever since I've been on this site, I must say that I've been most impressed with the knowledge here.  In fact, it makes me appreciate much more what you guys do for a living.  Thanks!
  • Brad White
    Brad White Member Posts: 2,393
    Thermostatic Mixing Valve

    Danfoss/ESBE makes one which is fairly common to see and there are others. Simple and self-contained. When the boiler fires, yes, the valve forces boiler supply water back into the boiler return side to warm that up. Once the boiler is in the safe zone, the valve relaxes to release hot water to your radiators. You will see warmer water because of this and perhaps shorter firing cycles.



    These are simple but not a perfect solution. There are a dozen other things you could do, (outdoor reset, re-pipe as primary-secondary, etc.), but for simplicity, these are hard to beat.



    When an atmospheric boiler condenses, you will hear a hissing, like water on, well, a hot burner. Imagine that. Drops hitting a frying pan. So you may not actually "see" visible water in the pan.



    As the others have said, your radiators are likely so large (and the building shell improved we would hope?), that they are over-sized and satisfy with much lower temperatures than you ever thought.
    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"



    -Ernie White, my Dad
  • Mike Kusiak_2
    Mike Kusiak_2 Member Posts: 604
    Boiler vs.system temperature

    A Brad suggests, a thermostatic mixing valve will permit your boiler to operate at a high enough temperature to avoid condensing, yet allow the system temperature to adjust itself to the requirements of the given heat load.



    The thermostatic valve "decouples" the boiler from the radiation, so each may operate at their own optimum temperature. For a given heat requirement, the radiators will not be any hotter, but the boiler will be, which avoids the condensation problem.



    The actual valve is very similar to the engine thermostat in your car, which regulates the flow of water through the radiator to maintain constant engine temperature. It should be fairly simple to add this valve to your system without too much alteration to the nice piping.
  • Sweet_Lew
    Sweet_Lew Member Posts: 116
    edited January 2011
    Taco pumps are noisy

    Jamie Hall is probably right. I run a Taco 007 and you can hear it from each radiator. Initially, I thought there was air in the system so I bled all the radiators and there wasn't a lick of air coming out. Just to confirm this, I just had my 007 seize on me today. When the heat came on, it was quiet and only half the radiators were hot. Right then and there I knew the pump was FUBAR'd. Once swapped out the noise returned.



    Oh, and I'm pretty sure that clank is the pump. I just listened to a cycle and when the pump turned off it made the same "clank". However, it's much louder than the last pump. If you can, upload a video of the pump running and then have someone turn the t-stat off so the pump shuts off.
  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    Taco pumps are noisy?

    I have four Taco 007 pumps; three of them are 007-IFC, and one is just plain.



    After about a year (they were all new in May 2009), one of them became noisy. Sometimes it sounded like air was in it, sometimes it sounded like a little gear train with too much backlash. (I know there are no gears in this pump.) It worked fine other than the noise. I had trouble thinking it was air because I had a Taco 49-125 air separator just before two of the circulators, including the noisy one.



    http://www.taco-hvac.com/en/products/4900%20Series/track_file.html?file_to_download_id=15268



    I replaced it with a new one, and it can be heard only if I place my ear within about a foot of it. Same is true of the others. I can hear it if I place my ear very near the baseboard upstairs, but it makes less noise with my ears right next to the baseboard than I can hear from the fans in my computers that are downstairs.



    When a circulator stops, one of them it makes a slight rattle. Sort of 2 or 3 gentle taps. I suspect it is is just the rotor dropping down on to the bearing as it is no longer hydrodynamically lubricated with the water. I could be wrong about this, of course.
  • Brad White
    Brad White Member Posts: 2,393
    edited January 2011
    The ESBE/Danfoss valve is

    not really a decoupler, but is a mixing valve.



    When installed on the return with a supply bypass piped into it from downstream of the circulator, it blends in HWS to the return until the boiler is in the safe temperature range.



    Once the boiler is in that range, say 140F, that is the temperature that leaves for the radiators. The radiators will see the boiler temperature, whatever it is, but it will be warmer.

    Right now, the boiler barely gets above 120 and 110 was recently noted.



    Now, a 4-way mixing valve, at the outlet of the boiler, would in fact decouple the radiation from the boiler. That would normally be my first choice and will also serve to protect the boiler (when a return sensor is used as a low limit). So many ways to go about this.
    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"



    -Ernie White, my Dad
  • Sweet_Lew
    Sweet_Lew Member Posts: 116
    @ JDB

    Sorry, that was what I meant. The pump itself is NOT noisy, but is generates a low pitch frequency through my pipes\radiators.



    Update on the "clank". I called the heating pro back out to investigate the loud "CLANK". He said it wasn't normal and is replacing the pump again as I type.
  • heatmiser
    heatmiser Member Posts: 16
    noisy taco pumps??????

    want to know how to stop a noisy taco pump?????put on a grundfos!!!!!! if nothing else they are prettier!!! 
  • Gravyfries
    Gravyfries Member Posts: 19
    Video of Clank!

    I'll have to digest all this great info everyone.  I did manage to take a video of the pump making that clank per Sweet Lew's request.   Here's the video on photobucket.  I could only get sound if I opened it with quicktime.  Its from my phone.

    http://s120.photobucket.com/albums/o181/pandfac/?action=view&current=VIDEO0013.mp4





    Also, Is there a document somewhere that explains the differences between bypass, thermostatic valve and 4 way mixers?  I'd love to do a little research so I'll have an idea when I call them back out. 



    Thanks!
  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    Wow.

    One of my Taco 007's (that is also black, which I am sure has nothing to do with this) makes a slight rattle as it stops. Nothing like that. I do not like the sound of that. I am just a homeowner, though. It also sounds kind-of loud while running, unless that is the sound of the boiler firing or something.



    (Should not the piping from the pressure relief valve be copper or brass?)
  • Mike Kusiak_2
    Mike Kusiak_2 Member Posts: 604
    edited January 2011
    Old boiler replacement

    Saw a photo of your old boiler along with the pump video. Seems to have been in pretty nice shape. Curious why you replaced it?



    Honestly, don't think you will notice too much fuel savings with the new boiler.



    Were you experiencing condensation with the old one, as it was of the same type construction and piped similarly to the new Burnham? Don't see any obvious signs of corrosion.



    Did you say that it lasted 40 years under these conditions?
  • Sweet_Lew
    Sweet_Lew Member Posts: 116
    Same noise here

    I started my own thread so I don't thread jack this one, but that's the same noise my new 007 is making as well when it shuts off. The heating pro doesn't know what is causing it. =/
  • Gravyfries
    Gravyfries Member Posts: 19
    old boiler

    It was in decent shape overall. It seemed to slowly drain my wallet. First year it was a pump. Then I had to get a new decoupler for the pump. Every 2 years I'd get a new thermocouple. Rust from the cast iron would fall and put out the pilot. I did get a new pilot. I was told my guage was 6 lbs off [they estimated]. There always semed to be air in the system. Every season i'd be afraid to see what would happen next. Looking back I should have probably kept it for a few more years but frankly I was tired of waiting to see when it would break. I also think the basement had flooded before I got there.
  • icesailor
    icesailor Member Posts: 7,265
    New Boiler:

    What happens when too much "new" is learned and not enough "old". That new boiler isn't much different than the old one. No one noticed that the old boiler was running at the temperature that the new one is. Now it is a problem? Where? This was an old gravity conversion. They ALL work like this that were converted. Like someone said, the house is way over radiated. It has "natural" outdoor reset. Set by the heat loss of the house and the temperature of the house. Way back when, they made nozzle orifice's to put in the unions of big gravity radiators. Along the way, the house was insulated and tightened up. I'll bet that the system won't go over 150 degrees on the coldest day. Let alone design day, now at -30 degrees.

    The installer did an awesome job. His price was in the middle. With all that screw pipe, he didn't make the money the low bid might have made with copper.

    I'm sure that there was no discussion of how to make this system more efficient. Because "I" know the problems with high volume water systems, I would have offered an explaination of the problems and solutions to make the system better. I wouldn't have gotten the job. "Give them what they want".

    That boiler is lucky if it is 80%. A Weil-McLain GV Gold Boiler is non condensing and has primary and secondary pumps. And 87%  It would have pumped this system all day at whatever water temperatures needed to heat the system.

    I personally would suggest leaving the thing alone. A thermostatic valve would be nice but I would have zoned all those circuits off and better control over areas of the house. But it seems like the system works fine as is. The gas boiler is acting exactly like a normal gravity system. One thermostat starting the burner and the pump.

    Extrol tanks aren't supposed to be mounted in a horizontal position. Read the manufacturers instructions. At least, Amtrol's instructions. Amtrol suggests premature failure due to air in the water side.

    If this was oil with a tankless, all h&$$ would have broken loose. Maintaining a minimum boiler temperature would have caused the first radiators to get hot and the last ones to never get hot.

    This is the perfect replacement. With more thought, it could have been made better.

    JMO,
  • Brad White
    Brad White Member Posts: 2,393
    To my ears

    that almost sounds like the relay opening. Could be the pump, just sounds like the relay to me.
    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"



    -Ernie White, my Dad
  • Gravyfries
    Gravyfries Member Posts: 19
    Thanks

    I guess I'll get from under the bus now, hahaha.  Those tire tracks hurt! 



    I admitted in my first sentence that I don't understand these things at all.  Perhaps a little more background info is needed.  There were two bids more expensive.  I didn't go with them for other reasons than price.  One, who is has a great reputation in town for fixing boilers only measured EDR and I knew that wasn't gonna work since the boiler he was going to put in was larger than my 40 year old boiler!  I thought it was odd for the one company everybody raves about didn't even consider a heat loss!  The highest bidder has a great reputation but I was getting too much of a salesman vibe whereas I really wanted to get more into the details of what would have been done.  The quote was even worse.  It was just hard to understand.  Ice, I really was looking for improving the system and not lowest bidder.  Two of the four bids would have put a larger radiator than my old one, I at least knew that wasn't going to work.  The other two bids came in at the same size (but two totally different 80% eff models).  I'm sure my new boiler is oversized too as much as I tried to eliminate that.  I would have loved to have gotten an honest technical expert to show me how to improve what I had.

    I still should have them come out and look at my pump.  I don't know if they would agree about the thermostatic valve but I think I should ask.  I just want this thing to last a long time. 
  • Charlie from wmass
    Charlie from wmass Member Posts: 4,195
    Sand hole in the casting

    Thats my guess in the circ noise. a little caviatation there too. But as loud as that circ is when running, sand hole.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
    https://heatinghelp.com/find-a-contractor/detail/charles-garrity-plumbing-and-heating
  • icesailor
    icesailor Member Posts: 7,265
    Installed Boiler:

    Fries,

    You misunderstand me. I think that your boiler is just fine. I think that it is just the right size for the application. In fact, it may be a tad oversized but if so, down fire it. You said that the rooms heat up just fine, just that the water temperature in the system doesn't seem to go that high.

    You need to carefully and as accurately measre the outgoing temperature of the boiler water going out to the system and the return water coming back. If it is 20 degrees different, that's a lot of BTU's going into the building.
  • tim smith
    tim smith Member Posts: 2,398
    Re: boiler noises etc

    Fries, I would have them pull the pump out of the veloute and check for debris in the impellar. That is quite often the problem with these small circs. Also, regarding the only getting 120 degrees, Burnham just recommends that a bypass pipe and ball valve be installed between the supply and return pipe at boiler. This will allow you to raise the return temp up on large volume systems like this. The thermostatic bypass is a nice addition although but just $$.
  • Gravyfries
    Gravyfries Member Posts: 19
    edited January 2011
    Hmmm

    Interesting.  Tim I was out yesterday and was unable to post.  I did put my ear up to the cartridge and was able to hear some debris moving around in there.  Would that be loud enough to travel through the first floor radiators?  Its not loud in the basement.   Also, if I do the bypass piping that will allow the water to get warmer without setting it to a particular temperature like the thermostatic valve?



    Charlie, most of that noise on the above video is really the burners firing.  I think you can hear the pump but not totally sure.  The sound is mainly upstairs.  I managed to take a few more small videos of the sound upstairs.  They aren't great but you can hear the whining (or whirring) sound I was talking about.  One is in the living room and one is from the dining room.  Also, if it is cavitating I would eventually want to have the expansion tank moved further along the return line as close to the pump as possible, correct?



    Ice, I've heard about firing down but do not totally comprehend what that means.  I'll have to look it up



    Living Room / Foyer radiator.  I think the pop in the first few seconds is the radiator.

    http://s120.photobucket.com/albums/o181/pandfac/?action=view¤t=VIDEO0001.mp4 



    Dining Room radiator.

    http://s120.photobucket.com/albums/o181/pandfac/?action=view¤t=VIDEO0004.mp4



    Thanks!
  • TonyS
    TonyS Member Posts: 849
    Several points

    The pump sounds bad. I would replace it with a 3 speed pump  and run it on low.

    Your system is 2 pipe direct return, I can tell by your pics that the returns were not reversed. So running the pump on a lower speed will more readily mimic gravity flow and you will find more even heating throughout your house.

    Second point is this and this is just my humble opinion from working on gravity systems for over 32 years. There is no need for a boiler bypass or any type of device to bring the boiler up to temp. I work on and maintain boilers ranging from 1 to 100 years old ( and there's more of them than you think) I just cleaned 2 milivolt gas gravity boilers from the 50s last week. Believe me, I wish flue gas condensation would kill these boilers. I maintain gas boilers from the 60s,70s,80s,90s,all without bypasses and they just keep going and going. These boilers gravitate all remaining heat into the house when they cycle off and are usually room temperature when they start again. Since most of the City of Reading has been turned into a section 8 rental Dump These boilers will not be replaced until they actually fail no matter how hard I plead. Why should they, your tax money pays for the rentals heat no matter how inefficient it is. Better not go off on politics here, Dan will delete my post.

    Point is, Your install is fine and will work for many many years.
  • Mike Kusiak_2
    Mike Kusiak_2 Member Posts: 604
    Fries, you worry too much

    I agree with Ice and Tony. Your new install will work fine for many years to come.



    I have an identical Burnham 205 in a commercial building with cast iron radiation. Most of the time the heat is setback to 45F. When the cold start boiler fires, the system is much colder than yours. Water temperature rarely if ever gets above 120F. The boiler has been working this way for 18 years without problems. The only sign of condensation is some fine rust particles in the burner pan.



    I would recommend cleaning the heat exchanger at least every other year. If you do neglect it, there can be a buildup of rust which could clog the exchanger or could cause large pieces to drop on the pilot as you experenced. Remember, every boiler needs proper annual maintenance and cleaning.



    Dont worry about possible oversize.  With the high mass high volume system you have, all the available boiler output is stored in the system water and radiation. With a larger boiler the only real effect is that the boiler will run for slightly shorter cycles.
  • Steve Whitbeck
    Steve Whitbeck Member Posts: 669
    Old boilers

    Sales people like to tell people that their 40 year old boilers are 60% or less eff.

    They were at least 70% eff.

    Your application would have been perfect for a mod con boiler.

    Sounds to me like there heat loss was a little on the low side.
  • Mike Kusiak_2
    Mike Kusiak_2 Member Posts: 604
    Some old ones were even better!

    I recently did combustion testing on the Burnham 205 and a similar sized 1940's design National gas boiler. To my surprise, the National had a better steady state efficiency.



    Under similar conditions, the 205 measured at 80.2% efficiency, 465F gross stack, 50.7% excess air and 3 PPM CO.



    The old National read 81.5% efficiency, 447F stack, 42.8% excess air and 4 PPM CO.



    The basic efficiency of atmospheric boilers has not really changed for 75 years, What has changed is the method of rating them, and the control of standby losses with flue dampers and electronic ignition.



    What I understand from reading some of the old literature, many years ago the AGA standardized basic atmospheric efficiency at 80%, no more no less. It would have been easy to go higher, but other factors like condensation in the old masonry chimneys prevented it.



    When the DOE and AFUE ratings were established, the rated efficiencies suddenly dropped because stand by losses were taken into account, but the basic combustion efficiency of the atmospheric has not really changed.



    One notable exception is the new Burnhan ES2. Recent readings I took were efficiency 85.9%, stack 266, exess air 37.5%, CO 8 PPM. With the very low stack temp, you can see why it can't be vented directly into an unlined chimney.
  • Steve Whitbeck
    Steve Whitbeck Member Posts: 669
    Efficiency

    Mike

    Common mistake - What you tested was combustion efficiency not thermal efficiency.

    What you tested was how efficient the burner burns the fuel.

    It takes a labrotory to test thermal eff.
  • Mike Kusiak_2
    Mike Kusiak_2 Member Posts: 604
    Combustion efficiency

    Yes, you are correct that what I am measuring is combustion efficiency, not thermal efficiency. Combustion efficiency however, does consider more than how well the fuel is burned. It also includes how well the heat of combustion is transferred to the heat exchanger.



    If for example the heat exchanger is inefficient or sooted up, the transfer is reduced so the stack temp will rise and consequently the combustion efficiency will drop.



    A true thermal efficiency test would compare the heat of combustion to the boiler output temperature and flow rate, which would actually tell you how much useful heat the boiler produces. But this is not the method used to calculate AFUE or DOT ratings.



    AFUE, according to the ASHRAE 103 standard is actually calculated in the laboratory by a combustion efficiency test. The total heat loss up the stack is measured by flue gas temperature and mass flow rate, and compared to the higher heating value of the fuel used. Any heat that is not lost up the flue is considered useful heat, including the heat transferred through the jacket. That's why manufacturers can actually increase their AFUE by using less jacket insulation. There is no actual meaurement of the amount of heat transferred to the boiler water in laboratory AFUE testing.



    So while it does not exactly correspond to true thermal efficiency, a combustion test can still give a useful idea of the actual efficiency of a boiler.
  • Steamhead
    Steamhead Member Posts: 14,842
    Au contraire, ME

    since most owners don't want to bleed radiators every so often, air separation is essential even on gravity conversions like mine. Especially mine, since I'm too busy working on other people's systems to want to spend that much time on mine!
    All Steamed Up, Inc.
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • Brad White
    Brad White Member Posts: 2,393
    But...

    Unless you have a top-down gravity system, your piping is pretty much guaranteed to direct excess air to your upper reaches by design- at least the upper part of any radiators.  Air issues near the boiler and at the circulator would be rare indeed and quickly solved.



    As far as homeowners not wanting to bleed their radiators, around here it is an annual if not ongoing tradition. Ever since coal went away as the dominant fuel, it gives the average HO a chance to do manly things :)
    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"



    -Ernie White, my Dad
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,837
    Good points Frank and Brad...

    I wasn't considering a down feed gravity system.



    Frank, I have at lest 2 dozen gravity conversion systems out there and no air scoop on them and I have never been back to bleed air and have never heard back from dis-satisfied customers. They were all up feed systems with the radiators bottom-bottom tapped. My suspicion is that thanks to the Dead Men over sizing the radiators based on the open window proposition, that there is plenty of head space available to trap air and not create discomfort issues.



    A conventional air scoop will do absolutely no good on a system with air in the upper reaches, and as for micro bubble resorbers sucking air off the next closest planet with oxygen, I've got some land off the east cost of Florida I'd like to sell you :-)



    Just sayin'... We can agree to disagree. I'd rather spend the $30 bucks on water conditioning chemicals.



    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • GreggShadduck
    GreggShadduck Member Posts: 9
    Is air removal required in all other situations?

    Thanks, Mark, for teaching -- yes, that's the word.  I appreciate it.



    You write: "Miser, when dealing with a space heating only, high mass, large volume

    standing cast iron radiation system, it is not necessary to have the

    usual air removal devices on the near boiler piping. Its a waste of time

    and money."





    I follow you.  But is air removal required in most or all other situations?  e.g. add indirect domestic hot water, as is so common?  Or adding some lower-temperature circuit to converted gravity/iron radiators?  This one I can follow you on: fin-tube, for instance, lacking the air collection ability of iron radiators.



    I am still trying to dope out the principle.



    Thank you!
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,837
    Yupper...

    If the CAST iron boiler is ONLY doing heating in a GRAVITY converted, up flow configuration (now pumped) system with LARGE cast iron radiators and distribution pipes, then no air separator is needed. But throw a DHW systems, or a small bore RFH system into the mix, THEN you MUST have an air eliminator/separator.



    As you are filling the system, you want to occasionally "bump" the pump to insure the boiler is completely wetted before firing, but as you are filling and burping, you definitely want the pump OFF.



    And we are ALL learning, provided we are paying attention...



    Thanks for listening and learning. :-)



    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • GreggShadduck
    GreggShadduck Member Posts: 9
    Bumping and burping

    Thanks, Mark, for your explanation.



    I'd like to ask: even though I am a father of 2 great daughters, and have done lots of bumping and burping, I do not understand whether you are suggesting that, while filling/purging a converted gravity system, one should bump the circ with, e.g. a stick of wood, OR with a shot of electricity (after doing one's best to get water in its works).



    FWIW my brother-in-law ran his Volvo without coolant, and I have kept its coolant pump (circulator) as a souvenir.  The guts of its bearings lay somewhere on the highway.  Ugly.



    Thanks!
This discussion has been closed.