I just switched to natural gas and had a new Weil-McLain steam boiler installed. (I originally had an oil boiler with steam heat.) It is a one pipe system and I have the old style radiators, except for wrought iron baseboards in two rooms (main level bathroom, and small "den").

I had no problem with heat in any rooms before the gas conversion and new boiler installation. Now two the rooms with baseboards (they are connected through the shared wall because the furthest room is on a slab) do not have heat unless I keep the thermostat set at 80 degrees. I can hear the heat trying to work... almost like clinking and ticking sounds (not banging and clanging).

The boiler company installed new vents, and made sure all the radiators are sloped correctly. But nothing has worked. They say there's not enough pressure building up, and that the pipe(s) to those rooms aren't big enough around. (Yet, it worked before!) They do have to come back for a third time, because several of the pipes/radiators in other rooms are clanging like crazy, so loud you can hear it outside the house, and it's impossible to get much sleep.

I'm worried that the installers changed the way the pipes were, right above the boiler, so the heat isn't getting to those two rooms. Does anyone have any other ideas? I guess I also need to know how high above the boiler the "header" (or equalizer?) should be?

Thank you for any help at all.

  • My idea is don't pay them until they get it to work properly.
    – ArchonOSX
    Jan 25, 2016 at 23:00
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    Compare the pressure of the new boiler to the old one, or the total BTU in. If the steam isn't generated in sufficient volume, it is condensing in nearby radiators before much steam is getting to the further ones. If you have throttling valves on the nearby ones, partially shut those. Feb 17, 2016 at 21:04
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    I agree with ArchonOSX. They broke your 100-year old house that was perfectly fine before even their father or grandfather got in the biz & regardless of who they have to consult or bring-in they don't get paid until it's literally perfect. Whether it's the wrong boiler, wrong expansion tank or wrong circulator pump (which is what you should've been upgraded to from gravity feed) is not your problem nor expense & if anything the entire system should only work noticeably better in every way.
    – Iggy
    Feb 20, 2016 at 16:31

1 Answer 1


You need someone that knows exactly how the near-boiler piping should be. Even a slight change in the diameter, the height above the water line, or the return system will affect the system's operation.

Also, on a one pipe steam system, the maximum steam pressure should not exceed 3 psig. The output of the new boiler should exceed the connected piping and radiation load by about 33%. On a steam system the boiler size is dictated by the connected load and not the heat loss of the building.

All radiator valves on a 1 pipe steam system are only for isolation of that radiator and need to be fully open or fully closed; no partially open/closed steam valves. Steam vent choice is also critical. Again, I say again, you need someone who knows steam piping and most people in the business do not!!! I rattled on about piping and etc. and forgot to answer the original question. Yes you can use baseboard radiation on a one pipe steam system. the minimum pipe/radiation size is inch and 1/4 if a short run or preferable 2".

  • As for having to raise the thermostat way up to get all rads to heat sounds as if the new boiler was down sized to the heat loss of the house. Big mistake; That works for hot water heat but not for steam heat: see 2nd paragraph in my original answer.
    – d.george
    Dec 20, 2016 at 21:34
  • Have you fixed the problems with your new boiler? It would be great to have an update on how the system is doing and what you did to fix the problems
    – d.george
    Jan 12, 2017 at 11:57

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