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2 Steam radiators not heating all the way across

Pete_18 Member Posts: 197
Have you tried taking off the vent to see if this makes a difference? This will let you know if a better vent or additional vent will make a difference.

What type of vent did you put on the radiator? What is the EDR for the radiator, or what does the radiator look like (sections / columns / height) and what size and width is the pipe?

Are your mains vented / vented properly?


  • Jon Silva_2
    Jon Silva_2 Member Posts: 5
    2 Steam radiators not heating all the way across

    One pipe steam radiator,30 sections,first three heating,last 1 heating,and the center of the radiator cold.Radiator is pitched,clean inside,new vent,and I disconnected the radiator to see steam output,and found plenty.Five radiators on this main,the first 2,and the last 1 are heating. The two in question are in the same room.
  • Jon Silva_2
    Jon Silva_2 Member Posts: 5

    Yes I took the new 1-a vent out and it seems like the steam goes across the top and down the last section and out of the vent hole. The radiator is section type and about 30 inches tall
  • Pete_18
    Pete_18 Member Posts: 197

    With the vent removed, are you getting steam out the vent hole early in the heating cycle before the whole radiator heats up? If so, perhaps your vent is way too high up on the radiator and needs to be retapped lower. I had a radiator that had its vent way at the top where you'd expect to find a bleeder for a hot water radiator and found that the vent closed very early because of the same problem, the steam just went right across the top.

    According to Gerry and Steve's ebook, the venting capacity of a Hoffman 1A set to 6 is very minimal (about the equivalent of a Gorton 6) and a Dole 1A is even less.

    If it heats up all the way properly with the vent removed then you probably want to look at a better vent. If you provide the # of tubes (and or columns) and sections that the radiator has, this can be used to help determine the minimum vent you'd want.
  • Bob W._3
    Bob W._3 Member Posts: 561

    The steam is doing what it is supposed to in traveling across the radiator at the top. It will fill the sections if the boiler runs long enough and its cold enough, provided there aren't other issues.

    I agree that a Hoffman 1A will probably not be enough venting for a 30 section radiator, assuming you want it to heat more than it does. Go to a Gorton C and see if that helps. That is a very large radiator. A better strategy may be to tap another vent hole below the exising vent and put a 1A on each. That way they will double vent until the top vent closes and the bottom will continue to vent. Dan suggests this in The Lost Art of Steam Heating. Get a copy if you can.

    If only the first 3 sections keep heating you may have another problem. For example, if your cut-in pressure is above 1.5 lbs, the Hoffman 1A won't open up to allow more steam in as the boiler cycles, since its "drop away" pressure is 1.5 lbs. The pressure must get below that figure before it reopens.
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