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Staple up pex question

ALH_4 Member Posts: 1,790
I have seen systems running at 180°F with pex in Thermofin that people love. Low mass radiant is more responsive than high mass and has less of a tendency to overshoot. It all depends on how picky you are about how the radiant floor functions.

Be careful of the hydraulics. The radiant floor will likely have much higher head loss than the rest of the emitters. It would be nice to have one of those little Wilo zone pumps for something like this.


  • Tom Hopkins
    Tom Hopkins Member Posts: 554

    I would like to add 140 ft of staple up pex with heat transfer plates under my kitchen which is covered in an engineered wood floor. I have an existing diverter tee system which I was hoping to tap into.

    I had a heating contractor come out to give me a quote and they estimated the job to be around $5-6000. They told me this would require adding a zone, installing a mixing valve (because the water temp needs to be reduced so the wood floor wouldn't warp), and adding a new pump.

    Can I just add the pex as I would a new base board? The subfloor is about 1 1/2 inches of plywood and the wood floor is 3/8 of an inch. Isn't the thickness of the combined floor enough that the temperature reaching the wood floor would be reduced to an appropriate level?

    Thank you in advance for the help.
  • jp_2
    jp_2 Member Posts: 1,935
    look here


    thats what you could use with your straight temperature.
  • nugs
    nugs Member Posts: 77

    I'll give you an answer that no doubt will have all the engineers up in arms but the truth here is that as long as the supply temp is'nt much over 180 it will most likely work fine. Will it overheat? Perhaps but you can simply add a zone valve to that section of pex, along with a thermostat or better yet a floor sensor. The only drawback is the zone won't heat unless the main zone is circulating. I'm sure you're looking to do this without spending an arm and a leg. If you want complete zone control then yes you need all that stuff. If you're willing to settle, you can do it a lot cheaper
  • jp_2
    jp_2 Member Posts: 1,935

    "most likely work fine"

    that says it all, why have all this fancy pex & radiator and such, if you just heat the basement hot enough, all the floors will be warm and you can save a ton of money on equipment!
    after all heat rises!!!!
  • Dave_4
    Dave_4 Member Posts: 1,405

    I did a DIY radiant staple up. Found a consultant from radiantpanel.com to help me design it. Probably cost me $3700 for 2000 sqft (pex, 2 manifolds w/ actuators, circ, relay and mix value). My point, once designed proberly, it wasn't too hard to put it in and you can save some cash too.
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