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Converting steam radiator to hot water

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I have an existing hot water system, and found an awesome old steam radiator to use on a porch enclosure project, and add to the existing system.

I would love some help on how to covert this radiator!

So if my inlet is "B", I would get a 1-1/4" bushing with a 1/2" hole for the valve, and then drill and tap a 1/2" hole at "C" for the return?

Or for the return, are there threads underneath what appears to be a cover at "E", that I should use for the return?

Can I then put the bleeder valve at "D," or should I plug this and put the bleeder valve at the top of the radiator?

What by the way, is the purpose of the threaded hole at "A" that is capped?

Thank you!



Comments

  • Jamie Hall
    Jamie Hall Member Posts: 23,323
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    Clearly was in use on a one pipe steam system. Before you spend a lot of time on it, check it for leaks -- water systems run at ten times the pressure that steam systems do, and have a dismaying way of showing up leaks in otherwise good steam radiators.

    OK, that said.

    Hole D needs to be plugged, and a bleeder installed high up on one end.

    Either A or E could have been used as the inlet for a two pipe steam system. You're going to want an outlet at location C -- and I at least have no idea what's there. It almost looks like it's part of the casting, which is sort of tiresome of it. You could also use A or E as the new inlet, with B as the outlet. Not normal at all -- hot water radiators usually have both inlet and outlet low -- but it might work quite well.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Steamhead
    Steamhead Member Posts: 16,842
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    It will work on hot-water if you connect the inlet to the top connection "A". I'm pretty sure there is a plug there.

    At "E", there is what looks like a little screw head. That's a 1/8" plug for a hot-water air vent. You'll probably have to drill it out and re-tap the hole.

    Pressure-test it first as @Jamie Hall said. Use water instead of air since it's much safer. If it holds 30 psi for 15 minutes, it's OK.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • retiredguy
    retiredguy Member Posts: 906
    edited October 2020
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    Could you show a picture of the length of the radiator to make sure that it is a rad that has nipples at the top and not just at the bottom of the sections.
  • harry777
    harry777 Member Posts: 2
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    Thanks for all the help!

    For retiredguy, I've attached a photo of the length of the radiator, showing that the sections are attached at the top.



    On the topic of length though, I probably should have included this photo from the beginning, as given this length using A and B as inlet and outlet wouldn't likely heat the other end of the radiator much.

    So I'm thinking that B should be inlet, C should be outlet, D should be plugged, and the bleeder should be put at E, and actually found a photo on the internet appearing to show that the hole at E is in fact for this purpose.



    It is still unknown to me why the radiator was produced with a blank at C, and why someone threaded a hole at A and then put a plug in it (I can tell it was done by hand as it is slightly off-center, and if this was for a two pipe steam system, why then wasn't it done at the other end).

    I appreciate further comments!
  • Jamie Hall
    Jamie Hall Member Posts: 23,323
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    Sounds like you're on the right track -- and it is a lovely radiator. So pressure test it, though (but be gentle -- no point in going over 30 psi).
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • JimP
    JimP Member Posts: 87
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    If you can drill and tap a 1/2" NPT opening at C it should work well. I'd recommend an air test even at a low PSI like 10 lb. You'd then be able to check the bottom with soapy water to find leaks. This radiator may have very small leaks and a water test, although good, may not show the leaks well. The air bubbles will be obvious. That installation is going to be a lot of work and you want to be sure the radiator is a good one for water.
  • retiredguy
    retiredguy Member Posts: 906
    edited October 2020
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    The reason that spot C is blank is that when the radiators are cast they all look like C since any section could be used as either end. The access threaded hole B is put in after the rad is cast. A 1 pipe steam rad will only need 1 hole for the inlet and outlet, the other side can be blank. (saves time and money in the mfg process).

    In 1972 or 1973 I had the pleasure of visiting the H B Smith boiler plant in Westfield, Mass. They showed us how they made their cast iron boiler sections from beginning to end including making the sand molds, installing the threaded top and bottom connections, pressure testing each section, and even pouring the molten cast iron. We were there a couple days and we were treated well, and even met a Mr Smith. (don't know which one)