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One Cold Radiator

Last October I replaced my old 4 section coal converted to oil boiler with a 3 section Dunkirk. For it's age, the boiler functioned very well. I replaced it as a precaution to failur and a lower fuel oil bill. The contractor installed the Dunkirk with copper pipe to my single iron pipe system. The house has 7 radiators. The first radiator off the main, at the junction of the copper pipe to the iron pipe, is the kitchen on the first floor. It is an 8 section tube type. The second radiator is the bathroom on the second floor. It is a small 2 section slant fin. The tee off the main to the kitchen is joined to the tee to the bathroom with a closed nipple. All the radiators get hot...except the bathroom. It's cold. The tee off the main to the kitchen is at a higher temperature than the tee to the bathroom. I've replaced the air valve on the bathroom radiator, the air valve on the supply main, readjusted the pressurtrol to a .5 psi cut in with a 2 psi cut out. Prior to readjusting, the cut out was 5 psi. The bathroom radiator is still cold. What could be the problem? All the radiators were hot with the old boiler.  


  • nicholas bonham-carter
    new boiler-cold rad

    why not post some pictures of your boiler supply piping. if not piped correctly, large amounts of water can be pushed up into the supplies, interfering with main venting, resulting in unbalanced steam distribution. the fact that you have copper supplies leads me to believe that the piping is wrong, and not to factory requirements.

    is the capacity of the boiler large enough for the radiation, [not the heat-loss]?

    what sort of main vent is currently on the main, or dry return?

    is the same thermostat still controlling the system as the original?

    if you turn off the boiler, and remove the cold radiator air vent, what would happen [have someone ready to flip the boiler switch off when you do this test!]--nbc
  • jimmythegreek
    jimmythegreek Member Posts: 56

    I would remove the cold radiator's air vent and run the system.  keep an eye on it and be ready to shut down the boiler.  If it starts blowing tons of steam out of the bleeder tapping for the vent u know the rad works.  Its probably a pressure issue and a balance issue.  Too much heat is cutting the boiler b4 the rad can heat up.  This is common in new boiler installs it seems.  You will probably end up replacing your main vents with larger new ones and your rad vents too.  This will hold back some steam and give this one a chance to heat.  As a precaution, check the actual floor valve to see if its open all the way and put a level on the radiator make sure its pitched.  A crappy radiator may heat after a while with an old boiler but a short cycle new boiler may not have a chance to heat it.  Post some pics of the boiler and the near boiler piping and the rad too.  This will help the folks here give you proper advice.
  • Steve_211
    Steve_211 Member Posts: 47
    Here are PIX

    Here are PIX of the boiler and the radiator.

    On the main is a Gorton #1. The original thermostat is being used, a Hunter Set & Save II installed in '91. Computations for square feet of steam

    for all the radiators plus the allowance for piping was done and the boiler output is adequate.
  • nicholas bonham-carter
    piping peculiarities

    have you compared the piping diagram in the installation manual for the boiler with what your piping is now, both in pipe diameters/materials, and riser heights?

    from the picture it looks to me as though the riser diameters may have been bushed down as they exit the boiler, and of course copper is certainly not desirable because of its high coefficient of expansion putting undue force on the block.

    i think the piping you have now is sending too much water up with the steam, and that is interfering with the venting, and steam distribution in the radiators.

    is the hunter thermostat set properly for steam heat? it probably has an anticipator to prevent temperature over-shoot, and if not set right, the thermostat can be satisfied before the radiators are all full of steam.

    an additional larger main vent, like a gorton #2 would help to fill the mains full of steam first before it rises up to the radiators above.--nbc
  • Steve_211
    Steve_211 Member Posts: 47
    Methinks you are right!

     I did not feel right about the use of copper with the steel pipe because of the different properties between them. I felt the contractor took the easy way out with the installation, using the copper. I asked the city inspector if it would cause a problem. He said no, it was permissible, and signed off on the installation. I've learned alot browsing this forum. My old boiler didn't have a header. The new one doesn't have much of one, along with an improper size for the equalizer. It nowhere near resembles what's diagrammed in the boiler manual. I've concluded that the near boiler piping has to be redone. The next question is how to find a reputable pipefitter or a recommended one in my area that knows what he's doing and will do the job right?

     Regarding the Hunter thermostat, there is no heat anticipator as was in my old round Honeywell.
  • Charlie from wmass
    Charlie from wmass Member Posts: 4,322
    Steve there is the find a contractor section at the top of the page.

    Search by state as the zip code is not also accurate. Where is your area? Looks like the Pioneer Valley area of MA with that piping job.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • Steve_211
    Steve_211 Member Posts: 47
    I'm in the NY metro area.

    I'm located in Passaic, NJ.
This discussion has been closed.