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converting a radiator

is it possible to use a freestanding 4 tube radiator originally used for steam, and convert it into a moniflow hot water system. If so how would it be piped, in terms of size piping, and which tappings do you use. Its a temporary affair for now just curious if it would work. Thank you


  • It depends

    how about posting a pic so we can see the radiator? Then we can tell you for sure.

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  • Are the radiator sections connected across the top as well as the bottom? If only connected across the bottom, there's no practical way to bleed out the air. You'd have to install a bleeder in each and every section. Won't say it's impossible, but it certainly wouldn't be easy or practical.

    If connected across the top AND bottom, they can be used for hot water.

    If it was used in a one-pipe system, be forewarned that removing tapping plugs is a ROYAL pain. Unless you have incredible self-control, I'd keep children far from earshot lest they be asking mommy what those words you're shouting mean. Think, A Christmas Story, with dad in the basement working on the furnace...

    Before attempting to remove a tapping plug, repeated spray the area with cheap silicon spray (petroleum distillates will be the first ingredient in the list) over a couple of days. The bolt-like head on most is tapered and I've never found a socket wrench that will engage them well. After that you may well try a Stilson (pipe) wrench and find that you just round the thing off. Be prepared to drill out most of the plug and then CAREFULLY cut or grind down to the very top of the thread lands in three or four places. Then you'll be able to remove everything.

    Radiators used in steam systems tend to have lots of accumulated gunk. I highly recommend that you take the rad outside and flush it with clean water numerous times and in different positions--especially upside-down.

  • I'd also pressure test them before installing. Steam rads worked on very low pressure compared to water and with the generally higher corrosion are subject to "nipple rot". Even if they didn't leak with steam, I've seen them leak with water. Pressure testing with water is generally easier and safer than testing with compressed air. 30 psi or so is plenty. If you see TINY weeping leaks under full house water pressure they probably won't leak when installed in the system, but hope for zero leaks after about 20 minutes.

  • Thank you for that advice mike, never thought about that. thats a solid bit of knowledge thanks again.
  • World Plumber
    World Plumber Member Posts: 389

    I found it easier to drill and tap the old plugs then to get them out.
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