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steam to fhw conversion

alan_17 Member Posts: 1
I am converting a two pipe steam system over to fhw and will be changing all the piping to pex. I will be leaving a small stub from each radiator and connecting in. Do I need to do anything to the thermostatic radiator trap on each and will it effect my flow rates (restriction). Any ideas?


  • Steamhead (in transit)
    Steamhead (in transit) Member Posts: 6,688
    Well, you need to realize

    first, that the vastly increased system pressure may cause the radiators to leak, and second, that they might not be big enough to heat the building with hot-water. Two very big risks, which is why my company does not do this type of conversion and will not work on a system someone else has converted.

    Oh, and if you're proposing a condensing boiler, the smaller radiator size may require the water to run hot enough that the boiler doesn't condense nearly as often as you expect it to, which would jack up the fuel bills. The owner might not be too happy with this, which may lead to a bad case of lawyer-itis.

    But if you pressure-test everything and find nothing leaks, and you do a heat-loss to make sure the rads can handle the load with the sharply reduced BTU output, and remove the trap elements, it just might work.

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  • steam conversion

    Why do you guys keep trying to do this. It is a bad idea. Don't do it. I have never seen one that could be termed a success. When I was helper my boss financed a college education servicing and repairing one of those in a commercial building that some hack did. Keep in mind the leaks don't always show up on the pressure test.
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