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Balancing one pipe steam heating

bucium Member Posts: 12
Our two story house has one pipe steam heat. We had our boiler replaced last year and sized appropriately for the size of the radiators. We also discovered we had leaks at some pipe/ radiator joints. Since those were taken care of the front of the house hasn’t been heating up. All the vents are new and we calculated the size of the vent for each radiator. At the front of the house we doubled the capacity of the vents on the main line ( even though as per calculations you don’t need to). Heat is not coming to the radiators and the pipe is heating somewhat past the main line. It is as if there is an obstruction in the pipes. We also took out the vents at two of the radiators when the boiler was on to see if air is being pushed thru or if any steam comes out, but nothing.

Any suggestions on how to tackle this are greatly appreciated.

Thank you


  • Jamie Hall
    Jamie Hall Member Posts: 22,187
    You mention that this happened after you took care of some leaks at the pipe to radiator joints. What, exactly, did you do?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    JUGHNE Member Posts: 10,914
    Timeline: did you do the new boiler and later repair leaks or at the same time.
    If later repairs then how did it heat between new boiler and repairs?
  • bucium
    bucium Member Posts: 12
    After we installed the new boiler, all radiators were heating up ( more or less) but we noticed the boiler was running out of water within 3-4 days. So we figured there must be leaks. We figured that at the joint between the radiator and pipe we were loosing steam. So we put in tape and tightened the connection. This was done gradually as we gradually found the leaks. The last one found was at a radiator st the front of the house and since that was fixed we lost heat to the radiators at the front of the house. We figured adding another vent on the main line at the front of the house would make up for the air that was venting where the leak was. But even adding the extra vent didn’t make a change. And what is more weird is that when we remove the vents at the radiators no steam comes thru.
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,576
    Was the boiler skimmed after the installation?
    Can you post a picture of the new boiler piping, and the main vents?--NBC
  • bucium
    bucium Member Posts: 12
    Yes of course the boiler was skimmed after installation. I am posting photos of the pipes and vents. Thanks
  • Fred
    Fred Member Posts: 8,542
    Have you checked the gas supply to the boiler? If the gas supply is not what it should be, the boiler will act like its too small for the connected load. You can clock it yourself or have the utility company check it for you.
  • bucium
    bucium Member Posts: 12
    The utility company is coming in tomorrow and I will ask them this question. Thank you
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,576
    Have you asked the installer what might be wrong with his new installation?
    If the main vent is temporarily removed, will steam come out?—NBC
  • bucium
    bucium Member Posts: 12
    The pipes heat up to the main vent and a past them but the heat doesn’t leave the basement. The main vents are hot when the boiler runs so I suspect the steam gets to them. The boiler heated up almost all the radiators until the leaks in the pipes were fixed. Thanks
  • ratio
    ratio Member Posts: 3,553
    To check if it's a capacity issue, try turning off a few of the radiators that do heat. That should free up enough steam to prove that the radiators do heat. It sounds more like a blockage to me, though; preventing the air from venting through the radiator vent even with the vent removed. Check the last piping change you made.
  • AMservices
    AMservices Member Posts: 608
    What condition is the radiators supply valve in?
    You said it was heating after new boiler was installed. Only after tightening the union steam stopped entering the radiator.
    Maybe the plunger broke and dropped on the seat.
    Make sure supply valve is all the way open.

    The packing nuts on radiator valves is where I find a lot leaks. Try repacking the valves to reduce your feed water. Might not look like their leaking, but they still could be.
    Leaks will vent air, so if a valve or radiator is leaking, steam will still favor a radiator, even if the vent is venting slower then others.
    Leaks will throw off the balance.

    Was the boiler skimmed right after installing?
    It's good to flush the boiler a month or 2 after it's been running steady. A lot of sediment that's been loosened by all the work on the piping is still making it's way back to the boiler.
  • neilc
    neilc Member Posts: 2,522
    bucium said:

    After we installed the new boiler, , , , So we put in tape and tightened the connection.

    we put in tape ?
    and were we really careful the tape didn't slip and end up blocking the union(s)? might wanna check one or all.

    The main is hot under these rads?
    the leaking unions might have been your venting,
    are we sure of main venting, and rad venting?
    or the valves are closed or needing repair as mentioned by others.

    known to beat dead horses
    JUGHNE Member Posts: 10,914
    As you repaired your leaks, you probably shut off the supply valve at each radiator.
    Sometime they will shut almost off and not open up even though they appear to be fully open.
    The disk/washer on the bottom can fall off and plug the inlet opening.
    You almost do not need a supply valve on a small one pipe system......you would just shut the system down for repairs etc.

    Unless the valve closes reliably, steam can enter but the condensate has difficulty draining out.
    And the fact that they can not modulate the heat output make them not useful.

    If you can unscrew the large bonnet under the handle and remove the guts for inspection then you will know if this is the problem.
  • bucium
    bucium Member Posts: 12
    We finally figured out the radiator supply valve at one radiator is broken. Valve looks oped but when my husband unscrewed the radiator and took a look at it the seat was obstructed. It turns out that we need to replace this valve but makes me wonder if there are any other valves like this at other radiator at the front of the house. Or would one radiator be sufficient to throw off the system?
  • ChrisJ
    ChrisJ Member Posts: 15,168
    I haven't had any issues with valves obstructing steam.

    But, I have had issues where radiators will hog steam so others wouldn't get any. The solution was to slow some of them down via smaller vents.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment