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Banging: Boiler shuts off after pump

Boiler after turning down thermostat:
https://youtu.be/iQPRsAWwY3c

I typed a long explanation but my browser crashed.  I am wondering if my system in my recently purchased home is wired incorrectly.  One of three zones bangs when shutting off, the one with the 4” return pipe from second and third floors.

Comments

  • mknmike
    mknmike Member Posts: 80
    Thermostat for the zone, and me shutting off right before the above video: https://youtu.be/dbQ1Qt_OWaA
  • neilc
    neilc Member Posts: 1,805
    post a picture of the large noisey tank and how it connects to the boiler system, one shot showing the piping,
    do the same thing for the small white tank,
    you should not have both,
    is there an isolation valve for the small white tank?

    and what is the boiler pressure at?
    known to beat dead horses
  • neilc
    neilc Member Posts: 1,805
    check that,

    boiler 22 psi,
    no isolation at white,

    post a video of the white tank, and follow the new copper to both ends where it connects to old system,
    any valves?

    i think you're pumping to the white, and sucking the grey dry, then it refills when the circs shut off,
    that's all air bubbles, and hot expansion going into the grey.
    i would isolate or remove the white,

    when was the white added? why?

    a temp fix would be to let all the air out of the white,
    take a air pressure reading first in case I'm wrong and you need to air it back up.
    known to beat dead horses
  • Jamie Hall
    Jamie Hall Member Posts: 18,951
    edited March 13
    Delightful old school thermostat -- it will run forever. The arc on opening the contact is quite normal.

    "That thing" hanging from the ceiling is the original compression tank for the system (the cute little white thing was added at some point by someone who didn't know what they were doing, and may -- or may not -- be needed). What you are hearing is air, or possibly steam, entering that tank from the rest of the system. What temperature is your system running at? There shouldn't be much air -- and there certainly shouldn't be steam.

    Do the circulating pumps shut off at exactly the same time as the boiler? Or do they continue for a bit to purge some extra heat?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 3,201
    edited March 13
    neilc said:

    post a picture of the large noisey tank and how it connects to the boiler system, one shot showing the piping,
    do the same thing for the small white tank,
    you should not have both,
    is there an isolation valve for the small white tank?

    and what is the boiler pressure at?

    Is the white tank for the DHW?
    Edward Young
    Retired HVAC Contractor from So. Jersey.
    Services first oil burner at age 16
    P/T trainer for EH-CC.org
  • neilc
    neilc Member Posts: 1,805

    neilc said:

    post a picture of the large noisey tank and how it connects to the boiler system, one shot showing the piping,
    do the same thing for the small white tank,
    you should not have both,
    is there an isolation valve for the small white tank?

    and what is the boiler pressure at?

    Is the white tank for the DHW?
    we don't know,
    known to beat dead horses
  • mknmike
    mknmike Member Posts: 80
    White tank is for the DHW, not connected to the heating system in any way if you don’t count the cold water intake to the heater that’s beyond the check valve.  I’ve taken another 6 videos I’m posting under user “mkn mike” on YouTube now.

    bleeding the top floor radiators has not made a difference.  Boiler definitely continues to fire well after thermostat is not calling for heat, but circulator pump shuts off instantly.  Is this normal?  Correct?  It did help me to bleed those top floor radiators as it built pressure, but it never settled above 30 psi.  Pretty steady around 25 psi except for when it bubbles and vibrates at the end.

    the expansion tank is between the ceiling joists in the basement, big loud one I’d assume is at least 10 gallons if not 20-30.  Pipe goes directly to it from the boiler.  Maybe I should just replace this thing with a nice little one like we have on the DHW.  That’s what I have in my house less than half the size in the same neighborhood.  

    Or maybe the boiler shouldn’t keep boiling after the call for heat ends.  
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 3,201
    edited March 13
    mknmike said:

    White tank is for the DHW, not connected to the heating system in any way

    Thought so

    It's hard to see your system piping because the camera man goes too fast past the stuff I want to see, therefor when I stop the video the still image is blurry



    Your system is a very old gravity hot water design. Probably coal fired. If you look around the basement you may find remnants of a coal storage bin near a basement window. the bin would be close to the original heater location for easy access of coal to the fire door of the boiler.

    sometime in the 1940s or 1950s, an oil burner was added to the boiler, the tank was probably put in the coal storage bin location (if it is in the basement) At some time in the 1960s or 70s that converted coal beast was replaced by a Packaged Boiler with a circulator pump. Sometime during the life of the system and when the addition to the home was made, a circulator pump was added for each zone.

    Within the last 20 years, the current boiler replaced the 1960s-70s boiler. That one will last you another 10 to 20 years. Your noise problem is air in the system that finds its way into the top of the boiler from the rest of the piping and radiators. The circulator locations on the return is not ideal, however, that is the way it was done in the 1940s. When the current boiler was installed the purchaser went for the low bid, or the contractor just wanted to go cheep. If the boiler was installed today, a well informed contractor would install the circulators on the supply side in a location just after the pipe that connects the expansion tank to the supply (hottest point in thew system) so that trapped air can find its way to the tank. You want all the air in the system to find its way to that expansion tank..

    Here is a test that is well written that will explain a lot about your system. It will give you a better understanding of how things work. The only way i can think of to stop the noise is to connect the pipe from the expansion tank to a different location on your system. but without better pictures of how that pipe is connected, it is difficult to say where.
    http://media.blueridgecompany.com/documents/ZoningMadeEasy.pdf

    Mr.ED




    Edward Young
    Retired HVAC Contractor from So. Jersey.
    Services first oil burner at age 16
    P/T trainer for EH-CC.org
  • mknmike
    mknmike Member Posts: 80
    edited March 13
    I am trying to get videos loaded.  I will go take some pics in a few minutes.  I’ve only got videos 1 and 2 of 6 loaded so far.

    1
  • mknmike
    mknmike Member Posts: 80

  • mknmike
    mknmike Member Posts: 80

  • mknmike
    mknmike Member Posts: 80

  • mknmike
    mknmike Member Posts: 80

  • Steamhead
    Steamhead Member Posts: 15,338
    Is it possible the gas valve is not shutting off instantly when the call for heat ends?
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 3,201
    edited March 13
    Regarding your Series 10 Honeywell thermostat, that has a 3 wire setup, and Jamie is correct, the spark is normal. Annual maintenance would include taking a burnishing tool and polishing the contacts in that thermostat. For it to be accurate, it must be connected to a Series 10 (3 wire) relay in the basement. When your new boiler was installed, I would have included all new controls and circulators and thermostats. but my price would have been a little higher
    Edward Young
    Retired HVAC Contractor from So. Jersey.
    Services first oil burner at age 16
    P/T trainer for EH-CC.org
  • mknmike
    mknmike Member Posts: 80
    White tank is for the DHW, not connected to the heating system in any way
    Thought so It's hard to see your system piping because the camera man goes too fast past the stuff I want to see, therefor when I stop the video the still image is blurry Your system is a very old gravity hot water design. Probably coal fired. If you look around the basement you may find remnants of a coal storage bin near a basement window. the bin would be close to the original heater location for easy access of coal to the fire door of the boiler. sometime in the 1940s or 1950s, an oil burner was added to the boiler, the tank was probably put in the coal storage bin location (if it is in the basement) At some time in the 1960s or 70s that converted coal beast was replaced by a Packaged Boiler with a circulator pump. Sometime during the life of the system and when the addition to the home was made, a circulator pump was added for each zone. Within the last 20 years, the current boiler replaced the 1960s-70s boiler. That one will last you another 10 to 20 years. Your noise problem is air in the system that finds its way into the top of the boiler from the rest of the piping and radiators. The circulator locations on the return is not ideal, however, that is the way it was done in the 1940s. When the current boiler was installed the purchaser went for the low bid, or the contractor just wanted to go cheep. If the boiler was installed today, a well informed contractor would install the circulators on the supply side in a location just after the pipe that connects the expansion tank to the supply (hottest point in thew system) so that trapped air can find its way to the tank. You want all the air in the system to find its way to that expansion tank.. Here is a test that is well written that will explain a lot about your system. It will give you a better understanding of how things work. The only way i can think of to stop the noise is to connect the pipe from the expansion tank to a different location on your system. but without better pictures of how that pipe is connected, it is difficult to say where. http://media.blueridgecompany.com/documents/ZoningMadeEasy.pdf Mr.ED
    Thank you.

    The underground oil storage tank in the front yard / brick walkway was remove around 20 years ago right before the previous owner purchased the house.  The previous owner probably did go for the “only do what you have to do” route.  This house was just a house to him, but one with history he respected and didn’t want to change if not absolutely needed.  Curtains from a coffee table book published in 1964 were still hanging when we bought the house.

    the driveway is on the opposite side of the chimney, and a coal room was unlikely in my opinion.  There’s a 2” pipe that comes into the house on the driveway side that I wonder if it was city steam perhaps.  I don’t know.  Maybe I never will.

    should the boiler keep boiling well after the circulator pump stops pumping?  I think that’s the cause of the unwanted boiling.  
    EdTheHeaterMan
  • mknmike
    mknmike Member Posts: 80
    post a picture of the large noisey tank and how it connects to the boiler system, one shot showing the piping, do the same thing for the small white tank, you should not have both, is there an isolation valve for the small white tank? and what is the boiler pressure at?
    Is the white tank for the DHW?
    Yes. White tank is not for heating system, but DHW.  I believe it should be ignored for the purposes of this discussion. I tried to upload pics. And I think video 6 posted above in the links of 6 should give an idea of what’s going on.  
    EdTheHeaterMan
  • Jamie Hall
    Jamie Hall Member Posts: 18,951
    You ask should the boiler keep boiler... and the answer is no. Ideally there would be what is referred to as primary/secondary pumping, and the boiler would have it's own pump to circulate water within it and a primary loop. I doubt very much that you have that! But all is not lost. You can change -- or have changed, perhaps (where are you? We may know someone who can make this happen) -- the control scheme so that the thermostat turns on its circulating pump, but the boiler is controlled by its own aquastat on the boiler. That would be set to whatever temperature you radiation requires, and would turn on the boiler if the water was too cool, and then turn it off again when it got up to temperature -- well below the temperature at which hot spots in the boiler could cause boiling when circulation shut off. There are various ways to do this...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • mknmike
    mknmike Member Posts: 80
    edited March 13
    You ask should the boiler keep boiler... and the answer is no. Ideally there would be what is referred to as primary/secondary pumping, and the boiler would have it's own pump to circulate water within it and a primary loop. I doubt very much that you have that! But all is not lost. You can change -- or have changed, perhaps (where are you? We may know someone who can make this happen) -- the control scheme so that the thermostat turns on its circulating pump, but the boiler is controlled by its own aquastat on the boiler. That would be set to whatever temperature you radiation requires, and would turn on the boiler if the water was too cool, and then turn it off again when it got up to temperature -- well below the temperature at which hot spots in the boiler could cause boiling when circulation shut off. There are various ways to do this...
    Wilmington, Delaware.

    I wonder if I could just turn the boiler set point down from 180 to 140 F.

    I ultimately want to switch to a modcon and will surely be buying some pumps unless the modcon has an internal pump like my triangle tube solo 110 in my house a few blocks away.  

    So if there’s no way to shut the boiler off sooner, I’d like to set the setpoint farther from a boiling temp, like 140 F where my old heater was set in my house just a few blocks away.  Additionally for safety reasons I think this would be wise because my tenant has all kinds of stuff pressed right up against radiators.  

    Is it easy to do this on a Weil McLane from 2011 175k btu out 210k btu in “gold” series boiler?
  • Jamie Hall
    Jamie Hall Member Posts: 18,951
    If 140 will provide enough heat, it should be a matter of adjusting the aquastat high limit. You may have to experiment a bit to find a temperature which provides just enough heat.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • mknmike
    mknmike Member Posts: 80
    Oh wow.  Much easier than I expected to change set point.  Rolled it back from 180 F to 140 F.  So easy.  Testing now. 
  • mknmike
    mknmike Member Posts: 80

  • mknmike
    mknmike Member Posts: 80
    I understand now how I really need a primary loop pump.  That would probably resolve the issue regardless of temp.  

    Boiler output temp was up near the 180 set point when I rolled back the temp to 140, and then did a call for heat on the second floor.  Boiler output temp dropped to about 100 I think and is now about 112 as I type this.  Oh, now 116.  To see if I can get the boiler to keep firing after the pump and see where it shuts off, I better go before it hits 120.  Running now, and will start video.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 3,201
    edited March 13
    @mknmike Said:
    the driveway is on the opposite side of the chimney, and a coal room was unlikely in my opinion

    That house definitely had a coal boiler. If the driveway was not close to the coal storage bin, the driver either used a wheel barrow or carried the coal in a canvas sack 100 lbs. at a time.

    Ask me how I know?
    My Dad



    Edward Young
    Retired HVAC Contractor from So. Jersey.
    Services first oil burner at age 16
    P/T trainer for EH-CC.org
    kcopp
  • mknmike
    mknmike Member Posts: 80
    Posting the video will take a bunch of time.  It will be vid 7 of today.  No bubbling even if I did still see some fluctuation in the pressure, just no crazy banging like before Thank goodness.  I could probably go a little lower, but have been told that running this at condensing temps is bad, and if like my house a few blocks down the street with a curve of:
    outdoor temp + water temp = 150 F
    … if this house is the same, this would be good to 10 F which is about as cold as we ever get here.  Rarely does it go below that.  

    It’s March now, and I’ve learned so much.  I think I can ignore this for several months and revisit in the fall / winter 2022-23.  

    So happy!  Thanks for the help!!  
  • mknmike
    mknmike Member Posts: 80
    edited March 13
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 3,201
    edited March 13
    I has a hunch that the expansion tank is installed in the "N" tapping. That is a built in air scoop in the boiler casting design. It has been in many of the Weil McLain CI boilers since the 1960s. Any air that accumulates in the system will find its way to that location and it is supposed to go to the expansion tank while the system is running. It is a great design feature. It is supposed to keep the air from getting into the the radiators. eventually all the air from the expansion tank can find its way to the radiators by a process described in Boyle's Law (having to do with the physics of dissolved air in water). Anyway, you don't have that problem. But there is a fitting you should have that would stop that bubbling noise at the end of each cycle.

    The whole concept is described in a book by @DanHolohan available here or on amazon.com Called Pumping Away and other really cool piping options...

    In this illustration from a Weil McLain IO manual you can see the concept
    The expansion tank is connected to the internal air scoop.
    This shows the cast iron block where all that happens

    At the tank there should be a fitting to prevent the air from leaving the tank. Here is the fitting you don't have

    If that fitting was there with one of the older heating boilers, it was removed when your current boiler was installed. But here is the reason for the noise

    As a result of something called Boyles Law (a physics thing) the air in the tank can leave the tank by being dissolved in cold water from the tank. Once that water finds its way to the system where the water is hot, it stops being dissolved and turns into micro bubbles, then those micro bubbles accumulate somewhere in the system and become big bubbles. In your case some of that air accumulates in the "built-in" air scoop, and when the system stops, you hear those bubbles returning to the tank.

    By lowering the temperature to 140°, you are reducing the whole Boyles Law temperature difference thing. to a smaller difference. Therefore you are removing less air from the expansion tank and that results in less noise from the air.







    Edward Young
    Retired HVAC Contractor from So. Jersey.
    Services first oil burner at age 16
    P/T trainer for EH-CC.org
  • mknmike
    mknmike Member Posts: 80
    I has a hunch that the expansion tank is installed in the "N" tapping. That is a built in air scoop in the boiler casting design. It has been in many of the Weil McLain CI boilers since the 1960s. Any air that accumulates in the system will find its way to that location and it is supposed to go to the expansion tank while the system is running. It is a great design feature. It is supposed to keep the air from getting into the the radiators. eventually all the air from the expansion tank can find its way to the radiators by a process described in Boyle's Law (having to do with the physics of dissolved air in water). Anyway, you don't have that problem. But there is a fitting you should have that would stop that bubbling noise at the end of each cycle. The whole concept is described in a book by @DanHolohan available here or on amazon.com Called Pumping Away and other really cool piping options... In this illustration from a Weil McLain IO manual you can see the concept The expansion tank is connected to the internal air scoop. This shows the cast iron block where all that happens At the tank there should be a fitting to prevent the air from leaving the tank. Here is the fitting you don't have If that fitting was there with one of the older heating boilers, it was removed when your current boiler was installed. But here is the reason for the noise As a result of something called Boyles Law (a physics thing) the air in the tank can leave the tank by being dissolved in cold water from the tank. Once that water finds its way to the system where the water is hot, it stops being dissolved and turns into micro bubbles, then those micro bubbles accumulate somewhere in the system and become big bubbles. In your case some of that air accumulates in the "built-in" air scoop, and when the system stops, you hear those bubbles returning to the tank. By lowering the temperature to 140°, you are reducing the whole Boyles Law temperature difference thing. to a smaller difference. Therefore you are removing less air from the expansion tank and that results in less noise from the air.
    Good stuff!!  The expansion tank seems to be piped right out of the fitting on the boiler, and doesn’t have the air valve you mention.  Sounds like that’s what I need.

    I will try to upload pics.

    on a new topic, I see my pumps require 20 weight oil every three months. Yikes!  That must be why the one is hot.  


  • mknmike
    mknmike Member Posts: 80

  • mknmike
    mknmike Member Posts: 80

  • mattmia2
    mattmia2 Member Posts: 5,532
    Do you have both a diaphragm tank and conventional compression tank or is the diaphragm tank for dhw?
  • mknmike
    mknmike Member Posts: 80
    edited March 14
    mattmia2 said:
    Do you have both a diaphragm tank and conventional compression tank or is the diaphragm tank for dhw?
    The white diaphragm tank is for the DHW.  
  • mattmia2
    mattmia2 Member Posts: 5,532
    I see the diaphragm tank is for dhw. I think you just need to let a little air out of the compression tank so it is water that flow out of the boiler in to it. Making the boiler cold start would help too.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 3,201
    edited March 14
    20 weight oil was an earlier discussion …. You should read it.  I posted some good info there. There is a funny ending too


    https://forum.heatinghelp.com/discussion/187795/what-is-no-20-oil#latest
    Edward Young
    Retired HVAC Contractor from So. Jersey.
    Services first oil burner at age 16
    P/T trainer for EH-CC.org
  • mknmike
    mknmike Member Posts: 80
    edited March 14
    @mknmike Said: the driveway is on the opposite side of the chimney, and a coal room was unlikely in my opinion That house definitely had a coal boiler. If the driveway was not close to the coal storage bin, the driver either used a wheel barrow or carried the coal in a canvas sack 100 lbs. at a time. Ask me how I know? My Dad
    I took this video showing how I struggle to figure out where the coal room would have been.  The room that I think makes most sense is one room with no windows.  Maybe it got dumped and had to be moved around the inside a lot. 

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 3,201
    This wall was the Coal Storage Bin location.
    The boiler was located close to the chimney, perhaps the boiler front door was facing away from the chimney wall (the back of the boiler was facing the chimney wall) which would mean the coal was stored to the left of the boiler.

    But that is not important in determining the problem you originally posted. But I'm good at going off topic on useless tangents. (Like you obviously LOL)

    Edward Young
    Retired HVAC Contractor from So. Jersey.
    Services first oil burner at age 16
    P/T trainer for EH-CC.org
    mknmike
  • mknmike
    mknmike Member Posts: 80
    This wall was the Coal Storage Bin location. The boiler was located close to the chimney, perhaps the boiler front door was facing away from the chimney wall (the back of the boiler was facing the chimney wall) which would mean the coal was stored to the left of the boiler. But that is not important in determining the problem you originally posted. But I'm good at going off topic on useless tangents. (Like you obviously LOL)
    Wow!  Thank you Ed!  

    I will look for remnants of walls that could have been for a coal storage room.  

    I was thinking the back center or maybe the laundry room because there’s old walls back there made of rough cut 1-by (that we cut the bottom off to assure we got rid of any mold, which also made it nice to hose out the basement floor last summer).  But like we said, that’s the opposite side of the 45-foot-wide house.  I agree that spot makes most sense.  The window should be easily accessible from the driveway, but I see no evidence of a walkway up to the house there.

    Hagley Museum does have pictures of when our neighborhood was first being built.  Maybe I can learn from them.

    It’s not too far OT when we are trying to understand the original design.  ;)

    https://digital.hagley.org/islandora/object/islandora%3A2604715/datastream/JPG/download



  • mknmike
    mknmike Member Posts: 80
    This wall was the Coal Storage Bin location. The boiler was located close to the chimney, perhaps the boiler front door was facing away from the chimney wall (the back of the boiler was facing the chimney wall) which would mean the coal was stored to the left of the boiler. But that is not important in determining the problem you originally posted. But I'm good at going off topic on useless tangents. (Like you obviously LOL)


    I was looking at the basement again today.  I am thinking that the low ceiling room under the steps with no windows was most likely the coal room (assuming there was one).  The space at the front of the house seems to have no evidence of walls removed and would be too close to the chimney / heater by DuPont safety standards I bet.  Sure, maybe they lured the coal in one of those front windows, but I’m thinking that DuPont probably designed this house to have the coal stored behind a brick wall away from the heater.  Maybe the coal scraps would get shoveled off the floor into the heater, but probably stored on the other side of the brick wall through this tunnel.  That’s what I think.

    Picture of rear of the house, and the tunnel that now has shelves in it.


    picture of the front of the house with chimney off to the right: