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Changing to a TVR valve on a Cast Iron radiator

I want to change the valves on the cast iron radiators for TVR valves which I have purchased. There are shut off valves on the same run of pipes going to the radiators in the same room.
My question is how do I change them?


  • Jamie Hall
    Jamie Hall Member Posts: 20,857
    what kind of connections does your new TRV have/ kind of makes a difference in how it might be done.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • hot_rod
    hot_rod Member Posts: 18,917
    Looks like that one is already bushed down to 3/4" NPT? Most valves are 3/4, angle or straight, just watch flow direction.

    There are valves known as convertible, where the knob removes and an adaptor and actuator can be added. Is there a brand name on that valve, it may be able to have a thermostatic head added.

    Here is an example of a valve that I added a pex connection onto. It is a convertible valve, remove the cap and add the head.This would go onto the return end of the radiator
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • bburd
    bburd Member Posts: 631
    @op, Where are you located? That is not North American piping practice, so the sizes are probably metric.

  • STEVEusaPA
    STEVEusaPA Member Posts: 6,050
    The plastic pipe clips and bent copper, I'm thinking UK or Ireland...just a guess.

    There was an error rendering this rich post.

  • Vulcanspotter655
    Vulcanspotter655 Member Posts: 2
    Hi I live in the UK. I've bought replacement valves from ebay so I lot cheaper than from a supplier. 
  • hot_rod
    hot_rod Member Posts: 18,917
    Interesting looking valve, install as shown in the pic. Is it a name brand, or a knock-off? Sometimes the bargain products are copies of a quality name brand
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • It looks like maybe the new one is the same manufacturer as the existing one in which case the spud nut may have the same threads.

    If so, your job just got easier: Drain the system to just below the radiator, undo the spud nut, spin off the old valve, screw on the new valve and tighten the spud nut. Pressure test for leaks.

    If not the same threads, you will have to remove and replace the spud to the radiator.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hourTwo btu/ per sq ft for degree difference for a slab