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Copper in Radiant Floor Heat???

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by LSaupe, Dec 14, 2007.

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  1. LSaupe

    LSaupe New Member

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    I purchased a home with radiant floor heat (which was installed about 15 yrs ago).

    What seems odd to me is that I have copper pipes coming out of the concrete. (I was anticipating PEX or similar).

    Is the copper I see just a termination, with a copper to PEX connection buried in the concrete, or is it possible (or even probable) that the whole system is copper?

    Pleading ignorance here, so any input would be greatly appreciated.

    Thanks and Regards,

    Larry S.

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  2. Tarmsolo60

    Tarmsolo60 Feeling the Heat

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  3. Nofossil

    Nofossil Moderator Emeritus

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    Hard to say what's in the concrete. I'd do a compressed air pressure leakdown test, and if it's good I'd stop worrying about what's in there. Possible it's all copper, but as long as the concrete stays dry it should be fine.
  4. LSaupe

    LSaupe New Member

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    Good info and link. Thanks for the replies on this.

    Larry S.
  5. BrownianHeatingTech

    BrownianHeatingTech Minister of Fire

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    I've seen it done. I don't recommend it, but I've seen it done.

    One of the early radiant installs in Maine was a copper-in-concrete install in a warehouse/office, running direct (180-degree) boiler water into the pipes, and with no cold shock protection on the boiler. Basically, everything that could be done wrong, was.

    And it works like a charm. I've also seen brand-new radiant installs not work because the installer forgot a minor detail, or used the wrong size pipe somewhere.

    As nofossil says, if it works, don't worry about it.

    Joe
  6. LSaupe

    LSaupe New Member

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    Thanks for the reply. Yep it works fine, so will just let it fly (though do wish I had a way of knowing what was living under the tiles/concrete though).

    Amother quick question. The floor inlet water temp is set for about 90 Deg F using what looks like a tempering valve. I have two radiant floors on separate zones so they don't both operate at the same time. Both floors though do receive water from the one tempering valve.

    Anyway, water leaving both floors is mixed, then sent to cold side of the tempering valve (mixing 180 Deg F with about 80 Deg F water when both are running at steady state conditions).

    What seems odd is that this valve does not respond to incoming water temp (I.e. change the ratio). E.g, if the main floor is running steady state (inlet at 90 Deg F and outlet at 80 Deg F, when the second floor kicks on, the now very cold exit water from the second floor (say 60 Deg F) goes to the temperaing valve and both floors now take 65 Deg F inlet water etc. The valve never changes position to regulate an inlet temp.

    Is this typical? My thought is that my valve is frozen but treally have no experience in these systems.

    Any input here is greatly appreciated.

    Larry S.
  7. BrownianHeatingTech

    BrownianHeatingTech Minister of Fire

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    Does it eventually balance out? Many of the thermostatic mixing valves that are used in hydronic systems are slow-operating designs. What brand&model;is the valve?

    Joe
  8. LSaupe

    LSaupe New Member

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    It does eventually balance out but takes quite a while, and pulls heat from the warm floor until they both start to heat up together.

    Unfortunately dont have a good visual access to the valve where it is located. I can, however see the adjustment screw just fine and the decal on that which reads "Mix Valve - Heatway - 100F to 200F".
  9. Eric Johnson

    Eric Johnson Mod Emeritus

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    Are you sure it's not a manual mixing valve? Does it have an adjustment knob? I have a cheap tempering valve for DHW that you have to set by hand.
  10. LSaupe

    LSaupe New Member

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    It does have a setting screw. Right to increase outlet temp and left to decrease temp. In that sense I suppose it could just be a manual fixed bypass type of thing but seems like an odd way to hook something up with two systems running intermittantly in parallel (I.e. variable heat load).
  11. BrownianHeatingTech

    BrownianHeatingTech Minister of Fire

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    Sounds like a bad mixing valve.

    Joe
  12. Gooserider

    Gooserider Mod Emeritus

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    A couple of possible idle thoughts that might help figure out what's inside the concrete... No promises that either approach would work, but might be worth experimenting...

    1. If you can disconnect one end of the radiant loop, or are sure there is a non-conductive section of pipe on the boiler side, try putting an Ohmeter on the inlet and outlet, using a low scale (no more than 2 Kohm) - If your loop is copper it should have a resistance reading that is close to zero. PEX or other non-conductive material should show much higher, probably infinite... Not sure about the metal wrapped or PEX-AL-PEX type stuff, presumably that would depend on if the connectors tied the wrapping together or not.

    2. See what a metal detector does - you might need one that is fairly powerful, and has the circuitry needed to discriminate between Ferrous and Non-ferrous materials so that you don't pick up the rebar, but you might be able to follow the loop if it's copper pipe, probably not if it's plain PEX, not sure about the metal wrapped stuff...

    Gooserider
  13. caretaker

    caretaker New Member

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    I have put in rediant heat systems before, the first ones were all copper, coil copper was in the concrete, then about ten years ago we went with the plastic pipe, I always like the copper better, but they both passed code, I think it's all copper, if you have a leak, your pressure will drop, it can be fixed but it's hard
  14. LSaupe

    LSaupe New Member

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    Thanks guys. Good stuff.

    Larry S.
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