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Steam Radiators not heating completely

Radiators not heating completley across.
Only a few sections getting hot. Replaced vents ,still no help.
1-pipe system.
Any help would be apprieciated.


  • Fred
    Fred Member Posts: 8,542
    Make sure your radiators are tilted back slightly towards the inlet pipe so that condensation can drain back to the boiler. Make sure the inlet valves are all the way open. on a one pipe, the valves have to be fully open or fully closed. No inbetweens. Do you have enough venting on your mains? If not, that will really slow the steam down and may not let it get to the rads before the boiler cycles off. Keep your pressuretrol set at .5psi for cut in and the differential (white wheel inside the pressuretrol) set at 1psi. That will keep your max pressure at no more than 1.5psi. Make sure the pressuretrol is working properly and make sure the pigtail that the pressuretrol is mounted on is not plugged. Take it off and clean it periodically. That get gunked up. Is the water in the sight glass fairly stable? (no more than 1/2 to 3/4 inch bounce) If it is more than that, you probably need to skim the boiler. Do you hear any pipes banging or water hammer? If so, that's an indication that steam is hitting water in the pipes and condensing. Make sure all your horizontal runs have some pitch to them (in same direction as the other pipes). Are your mains insulated? If not, steam may condense before it can get to the rads. I know these are a lot of things to check but they have to be right to get the most effeciency from the system. One last comment, what is the outside temp in your area? If it is mild, rads won't heat all the way across before the thermostat is satisfied and the boiler shuts down. That is normal operation. If these things don't fix your problem, post some pictures of your boiler and the near boiler piping so we can see what is happening there.
  • KC_Jones
    KC_Jones Member Posts: 5,742
    I am going to ask the simple question. Is the thermostat satisfied when they stop heating? It was 20 degrees here last night and mine still don't heat all the way across before the thermostat is satisfied. Did you try turning the heat up to 80 and see what happens? That would verify if it's a radiator is not heating or the thermostat is being satisfied.
    2014 Weil Mclain EG-40
    EcoSteam ES-20 Advanced Boiler Control
    Boiler pictures updated 2/21/15
  • Waterbury Steam
    Waterbury Steam Member Posts: 58
    Seconding KC Jones' comment--my rads don't heat all the way across unless the boiler is recovering from a setback or it's absolutely frigid outside. That's normal.