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Cold room. Too many radiators on one main?

Dberb Member Posts: 2
edited December 2022 in Strictly Steam
I have a 100 year old single family house with a one-pipe steam system, oil fired. There are 2 mains in the basement. One main serves 5 radiators (let’s call this A), and the other serves 7 (let’s call this B ). Both mains vent with Gorton #1’s, and are approximately the same length. All of the rooms served by Main A are warm, while some of the rooms on Main B are cold (with one that’s colder than the rest, 2nd from the end of the main). Is it possible that there are too many radiators on Main B, causing them to heat slower? Would sizing down the vents in the warm rooms on Main B (and/or Main A) help make the cold rooms warmer? Below are more details. 

Main A vents (in order starting close to the boiler, all Gortons unless otherwise noted): Living Room 5, 2nd Flr Bedroom C, Foyer 5, Dining Room VentRite set to 7, 2nd Flr Bedroom C.

Main B vents: Living Room C, 2nd floor Bathroom unknown (it’s very tight against the wall), Powder Room 5, 2nd floor Hallway 5, Kitchen 6, 2nd floor Bedroom unbranded D, Attic Bedroom C. The 2nd floor bedroom is the coldest room (4-6 degrees colder than the rest of the house), the kitchen and powder room are also fairly cold.

I have a nest thermostat, with the temperature controlled by a remote sensor in the cold bedroom.

I have calculated the EDR/air volume for each radiator and it looks like I can reduce the Main A bedroom vents to 6’s and the Main B living room vent to a 5. I’m not sure if this will help though. The Main B 2nd floor bedroom should also be a 6, but I’m not sure if I should reduce it that much.

Another problem could be that the mains are not insulated. I plan to do that. I have also read about the possibility of sludge in the radiator, so I may look into flushing some of them. Or perhaps trapped air needs to be bled. Our boiler is annually maintained by a professional, but I’m not sure if they do this work on the radiators too.

What should I try first? Any advice appreciated!


  • Long Beach Ed
    Long Beach Ed Member Posts: 1,188
    edited December 2022
    Either the radiators in the cold rooms are too small for the heating load, your venting is unbalanced or your piping configuration is faulty.

    I would measure the heat loss for each room to confirm that the radiators are properly sized for specific heat loss. Using the radiator sizing, check that the boiler is properly sized and that the piping sizes are correct. Check the configuration of the near-boiler-piping to assure proper steam quality. It that was correct I would to rebalance the venting. Throw away any unbranded or non-working air vents and replace them with quality, domestic vents.

    I doubt any radiator is clogged and there is no "bleeding" needed of steam radiators.

    It is unlikely that there are too many radiators on a single main. From what you mention that's doubtful unless the radiators are uncommonly large or the piping small. To determine that, we'd need the size of each radiator and the size of the main for the calculation.

    Any "professional" who maintains your heating system should be able to do all this or he should be replaced first.
  • nde
    nde Member Posts: 86
    They arent cheap but gorton 2 on the mains is what you want, at least on the slow one for sure. Imbalance on distinct mains is usually tied to bad main venting. So that is the first step to balance. From there you can test if bad rad vent by totally removing it at beginning of cycle and it should heat much faster with no vent (do not leave the rad ventless other than testing). But generally you want the fastest gorton on those farthest rads. Even then if one main is noticeably longer (say 10 or more feet) those rads at the end of the longer main will usually never be as hot as others but if well balanced should still be fully warmed by end of cycle.
  • gfrbrookline
    gfrbrookline Member Posts: 753
    edited December 2022
    I concur that your main vents are too small and you would benefit from G2's in general and would likely see some fuel savings. G1's are basically large enough to use as add ons to reach the pipe venting capacity when using G2's. Fix the main venting before swapping out radiator vents. It is also possible that the radiator in the cold bedroom may be too small to heat the room but we can not tell without knowing the heat loss of the room and the size of the radiator. Opening up the main venting will let steam hit your radiators faster and it may solve your problem.
  • gfrbrookline
    gfrbrookline Member Posts: 753
    Where are you located?