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Convert steam radiators to hydronic?

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RayWohlfarth
RayWohlfarth Member Posts: 1,552

Have you covered a steam system to hydronic? I have never done it myself. The old radiators have the steam inlet high and the outlet low on the other side of the radiator.

Thanks for your expertise

Ray

Ray Wohlfarth
Boiler Lessons

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 23,635
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    Good heavens, @RayWohlfarth — that's been talked about a number of times. I've never done it, but I know @Steamhead has… it can be done — but there are ptifalls.

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • JUGHNE
    JUGHNE Member Posts: 11,102
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    Are you converting an entire system or just some individual radiators?

  • mattmia2
    mattmia2 Member Posts: 9,944
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    They can't be steam only radiators, the sections have to connect at the top. They can leak at 15-20 psig when they didn't leak at 2 psig steam. I think those are the main pitfalls.

    Grallert
  • Steamhead
    Steamhead Member Posts: 17,003
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    Actually, @Jamie Hall , I've never converted an entire steam system to hot-water. And I never will. Way too many pitfalls.

    @RayWohlfarth , tell us a bit about the job, and how did they get such a bad idea.

    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • RayWohlfarth
    RayWohlfarth Member Posts: 1,552
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    Thank you all. They have a 100 year old building and equally old steam system. The customer installed a new VRF system and the rooms at the end of the building can't heat in cold weather, like below 20 degrees F. The interior rooms seem to maintain temperature. The steam pipes are leaking and they asked if they could put in a hydronic boiler and pipe it to the radiators using Pex. They are looking to connect the boiler to four radiators per floor, two at each end of the building and the building is three stories high. Like I said, i never did this and hope to help the contractor avoid a lawsuit. I appreciate the help

    Ray

    Ray Wohlfarth
    Boiler Lessons
  • hot_rod
    hot_rod Member Posts: 22,472
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    If the top and bottoms are connected they will heat with hydronic flow.

    With a conversion fitting they could just S&R at the bottom, with or without a TRV.

    A 3 story building would have 12- 15 psi on the bottom floor.

    Could be a lot of rust and sediment in them also.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    mattmia2
  • Jamie Hall
    Jamie Hall Member Posts: 23,635
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    Didn't mean you'd done a whole system. You wouldn't, and for good reason. Like… many good reasons. Nor is it something I or most folks would recommend.

    Seems to me, @RayWohlfarth , that your client's client or whatever would be best served if someone sat down and figured out first, why some of the radiators don't heat properly and, second, figured out why the steam pipes leak. There could be any number of reasons why some radiators don't heat properly, and most of them — particularly on two pipe systems — are both cheap and easy to fix.

    The leaking steam pipes is a bit of a puzzle. They rarely do, as they rarely rust, except for wet returns (which do) and occasionally low spots. All of which should, again, be easy and relatively cheap to fix.

    I presume by VRF system you are referring to a flavour of heat pump system — variable refrigerant flow? They're very nice. They may or may not play nice with an existing steam heating system — or one reconfigured for hot water. Whatever, fixing the steam or changing over isn't going to help problems with the VRF system.

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    mattmia2
  • mattmia2
    mattmia2 Member Posts: 9,944
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    Stem pipes usually only rust if the boiler is throwing liquid water up in to them.

  • DanHolohan
    DanHolohan Member, Moderator, Administrator Posts: 16,565
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    Ray, if the steam inlet is high, and the return is low then the radiator sections are connected both top and bottom. You could use those with hot water.

    Retired and loving it.
    mattmia2
  • RayWohlfarth
    RayWohlfarth Member Posts: 1,552
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    @hot_rod Thanks I will look into it. By the way, I saw Hot Rods repair shop in WV and thought of you

    @Jamie Hall Thanks, you bring up lots of good points. Yes it is a variable refrigerant flow system.

    @DanHolohan Thanks Dan I appreciate it. I will let you guys know how it works

    Ray Wohlfarth
    Boiler Lessons
  • Erin Holohan Haskell
    Erin Holohan Haskell Member, Moderator, Administrator Posts: 2,345
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  • RayWohlfarth
    RayWohlfarth Member Posts: 1,552
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    Thank you @Erin Holohan Haskell Youre awesome

    Ray Wohlfarth
    Boiler Lessons
    Erin Holohan Haskellmattmia2
  • Grallert
    Grallert Member Posts: 669
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    I've done a number of them but I really only use the radiators. Once I've converted them with a supply valve and return union I drop through he floor with 1/2 black pipe to preserve the look. I rarely used single entry valves. From there I used forsta pex and a manifold. This way everything in the living space looked somewhat original. If I had a leaker, which was rare, I would remove it, drain it flip it on it's head and fill it with hot water and sodium silicate and put pressure to it until it sealed up. Usually worked.

    Miss Hall's School service mechanic, greenhouse manager,teacher and dog walker
  • jumper
    jumper Member Posts: 2,331
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    Changing the pipes is the big job. Why not change pipes but stick with steam? Radiators have more heating capacity with steam. I'd consult Igor about air elimination. Steam is more appropriate for large buildings.

  • WMno57
    WMno57 Member Posts: 1,408
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    @Grallert Why? Seems like the conventional wisdom here is to keep it steam. Could you share more?

    Were these repairs to get the heat back on, or upgrades to working systems?

    Leaking returns, Leaking boilers?

    Replaced with conventional hot water boiler or ModCon?

    Client's idea or your idea?

    Commercial or residential?

    Any steam systems you feel are not a good candidate for this?

    Thanks