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2" pex for radiant heat

realolmanrealolman Member Posts: 513
I was on another forum and a guy posted that several installers told him that the larger the pex tubing for radiant heat, the better and faster it will work.  He said when they built his new house they were going to use 2" pex and even in the event of a power failure, he would still have heat days later.

I know what I think of that, but I'd like to know what you think of that.


  • SteamheadSteamhead Member Posts: 11,328
    Didn't know

    they even make 2" PEX....................
    All Steamed Up, Inc.
    "Reducing our country's energy consumption, one system at a time"
    Steam, Vapor & Hot-Water Heating Specialists
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    Baltimore, MD (USA) and consulting anywhere.
  • SpeyFitterSpeyFitter Member Posts: 420
    edited December 2009
    They make 2" Pex but...

    It is INSANELY EXPENSIVE and also requires specialized tools to join/work with it. I have a little Rehau/Everloc 2" pipe that is right beside my computer right now. It's got a cut out so you can see the robustness of the joining system (Everloc) with a couplilng. I'm sure it's good stuff but there are few applications I would use it over Aquatherm (Polypropolene) in.

    Your best bet with any radiant system for a back up heat source is to have a gas fireplace in your house. If the electricity ever goes out (you're planning on using an electric heat source i.e. boiler or heat pump? for your radiant?), the gas fireplace does not require power and will still run.

    It really depends on your anticipated power outage too. If the power can go out for days, then you might want to put glycol in your heating system. Radiant will still maintain some warmth for a day or so because of it's thermal mass, but if your power outages last 2 or 3 days and it's subfreezing temperatures, you would be playing with fire that way without an auxillary heat source.
    Class 'A' Gas Fitter - Certified Hydronic Systems Designer - Journeyman Plumber
  • ChrisChris Member Posts: 3,056
    Bigger is Better

    I don't agree. Should have asked him if he was increasing the size of his heating appliance to keep up heating all that nice cold water that is coming back to the boiler or increasing his pumps for all that increased head? Bigger is better right?
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • Mark EathertonMark Eatherton Member Posts: 5,582
    What I think...

    I think they are yanking someone's chain...

    Having actually wrestled with 2" PEx, I can guarantee you that you would NOT want to experience it.

    Think amorous boa constrictor on Viagra with a serious attitude problem, and you will get an inkling of what it is like...

    They obviously didn't know what they were talking about.

    BTW, they make PEx all the way up to 3" now, and rumor has it that someone is coming out with 4" in the future... I just can't imagine trying to handle THAT stuff.

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • MWMW Member Posts: 25
    4" Pex

    They do make 4" pex. I experienced this stuff on one occasion. It was a day which will live in infamy. We used it to run a set of under ground mains from a main mechanical room to a smaller mechanical room 160 feet away. I'm telling you this stuff is unruly. I still have nightmares about this experience and that was  2 1/2 years ago.
  • Charlie from wmassCharlie from wmass Member Posts: 3,918
    How many guys to crimp that joint?

    Well the loop lengths  should be fun to figure. I am guessing there was a typo. 2" Pex I am thinking one would better to go with wrought Iron if they want that much mass. I was on a tour in an old Victorian Green house and the radiant system for the green house was steam fired in 4" cast iron bell and spigot pipe.  I will bring my camera next time. Wisteriahurst was the name of the home.  It is in Holyoke,MA.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
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