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Connecting 15mm TRV (UK size) to 1/2 Pex?

skiereric
skiereric Member Posts: 55
edited July 2022 in Radiant Heating
I purchased a few Danfoss TRV sets off amazon realizing a bit late that it was shipping from the UK and was 15mm.

I am now trying to figure out how to connect this to my 1/2" Pex supply and return. My rads are Euro Stelrads, so I am able to connect into the rad, but the pex is the issue.

I am unsure of what to be searching for. Any ideas?

Comments

  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 3,511
    edited July 2022
    Return it to Amazon and buy the correct size. I'm sure it can be done, but I wouldn't want to be messing around with adapters.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour
  • Jamie Hall
    Jamie Hall Member Posts: 20,500
    Well, that's going to be interesting. Your best bet is probably going to be to find a push to connect fitting (like Sharkbite, but there are others (try McMaster-Carr) with the 15 mm thread and accepting your 1/2 inch PEX. Be sure you identify the thread properly -- you need to be certain of more than just the diameter, as there are both fine and coarse pitch threads, as well as tapered and straight.

    Since you got them from Amazon, you may have difficulty finding more information; Danfoss might be helpful, but might not.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • mattmia2
    mattmia2 Member Posts: 7,207
    I don't think the thread is 15mm, I think it is a compression connection for 15mm od pex. Could try a piece of 1/2" pex, it is about 20 thousandths bigger than 15 mm.
  • skiereric
    skiereric Member Posts: 55
    Got it. Return it is. 

    Any recommendations of TRVs for 1/2 pex?
  • mattmia2
    mattmia2 Member Posts: 7,207
    The US series of that danfoss with the body made for 1/2" pex. Or even better the version with an NPT inlet then you can adapt it to whatever you want.
  • hot_rod
    hot_rod Member Posts: 18,265
    How are you using it that you need Pex on both connections? Typically they fasten onto the heater on one port, tube connects to the other
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • mattmia2
    mattmia2 Member Posts: 7,207
    One side is BSP that screws in to the panel radiator(with a spud) and the other side it for 15 mm pex from the system.
  • skiereric
    skiereric Member Posts: 55
    Sorry.  I have 1/2 pex running from my manifold ports, the pex is connected to the valve by a G 3/4" X 1⁄2" PEX Compression Connector.

    My post was to see if an adapter could be used on the euro style 15mm trv as I am wanting to update my valves to TRVs.

    now curious to see if anyone here has a recommendation on TRVs for my 1/2 “ pex 


  • skiereric
    skiereric Member Posts: 55
    To clarify. The 15 mm is designed for 15 mm copper, hence the issue with 1/2 pex 
  • hot_rod
    hot_rod Member Posts: 18,265
    The conical thread should be standard from brand to brand, you just buy the correct nut and ferrule for the tube size. The valve body itself doesn't change, they are typically all 3/4".

    Caleffi has universal pex connectors, with a tapered ferrule and insert fitting taper they cover some tolerance issues. 15 mm= .590, 5/8 = .625"

    I have been able to get 1/2" copper into a 15 mm, by belt sanding the od :)
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • ChrisJ
    ChrisJ Member Posts: 13,905
    edited July 2022
    hot_rod said:

    The conical thread should be standard from brand to brand, you just buy the correct nut and ferrule for the tube size. The valve body itself doesn't change, they are typically all 3/4".

    Caleffi has universal pex connectors, with a tapered ferrule and insert fitting taper they cover some tolerance issues. 15 mm= .590, 5/8 = .625"

    I have been able to get 1/2" copper into a 15 mm, by belt sanding the od :)




    I don't know how much it matters, I mainly wanted to use that gif.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment