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psi for weil mclain eg55 steam boiler

sake1bssake1bs Member Posts: 4
I have a weil mclain steam boiler with 2 pressuretrol boxes. I have a basement plus 3 floors, i was wondering what the recommended psi would be for that type of building. It seems heat doesnt sufficiently get the radiators on the 3rd floor very hot, just a little bit past warm, Any help is greatly appreciatted


  • Charlie from wmassCharlie from wmass Member Posts: 4,138
    pressure should be as low as you can run them

    the luke warm radiators are not caused by lack of pressure in most cases, exceptions would be below a few ounces or holes in boilers allowing no effective pressure. Venting issues and piping issues are what we find cause poor distribution of heat.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • sake1bssake1bs Member Posts: 4

    ill look into that, but ive been reading alot about low pressure for a steam boiler , my boiler has 2 pressuretrols one is the common gray box and other is the one with the red reset button and see through window. the gray box is set at 4 psi and red button box is set at 10 psi, theres the basement with the boiler and 3 floors above it. I'd like to know if these settings are correct and if not what would be the optimal setting for this type of building
  • kcoppkcopp Member Posts: 3,538
    keep them....

    both at 2psi. You need more venting not more pressure. How are the main vents?
  • Charlie from wmassCharlie from wmass Member Posts: 4,138
    The see through box

    Is the manual reset and I would keep it around 6 pounds. it is there only for emergency shut off not control.  The second one I would set at 0.5 cut in and a 1 pound differential.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • sake1bssake1bs Member Posts: 4

    sorry im an extreme newbie when it comes to boilers, i am at the very beginning in learning, where are the main vents located and what do they look like and also whats their purpose if u dont mind me asking
  • sake1bssake1bs Member Posts: 4

    thanks very much
  • Saverio DeLucaSaverio DeLuca Member Posts: 5

    Your problem appears to be venting (radiator air valves) and/or thermostat location. First, simple and cheap. Set the thermostat to its normal setting. Let the boiler run until it reaches (satisfies) the set temperature and the boiler shuts off. Then, go up to the third floor and if the radiatiors are only a little past warm, raise the thermostat up an additional 4 to 5 degrees. When the thermostat is satisfied, then go back up to the third floor and check if the radiators are now hot. If they are still only warm, then it is likely the air valves on the third floor are of a size that are slow venting. Most top floor radiator air valves should be fast venting. If the radiators are hot, then the radiator air valve that is closest to the thermostat may be of a size that is fast venting causing the thermostat to be satisfied too soon and shutting off the burner before steam has time to reach the third floor radiators. You can relocate the thermostat to a more central location which is usually not practical. Or a more practical method, you can replace the air valve on the radiator that is closest to the thermostat with a slow venting air valve. If you still have the problem or if it gets some what better, then you can replace the third floor air valves with fast venting air valves in order to better balance the system.

    Like to know how it works out for you.
  • kcoppkcopp Member Posts: 3,538
    Main vents come....

    in different shapes and sizes. Some can be as big as a soup can others can be the size of a cell phone. Overall they look like regular radiator vents but the connection at the bottom is much bigger....1/2" or 3/4"  vs. 1/8" These get all the air out of the steam piping going to the radiators. radiator vent should only allow air out of the radiators. If the main vents are missing/ broken they put all the work on the rad vents and will slow down the heating process. Look for them at the end of the mains... or sometime on the returns by the boiler.
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