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Tankless Coil

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Alan (California Radiant) Forbes
Alan (California Radiant) Forbes Member Posts: 4,002
in THE MAIN WALL
They aren't very popular out West and out of over 700 customers, I only have one that has a tankless coil in his boiler.  It's a Crown G55 and I've been servicing it for about 15 years now; never a problem with his DHW until recently when the hot water will cool down when running any of the fixtures except the shower..  Any ideas for a solution.



As you might have gathered, I have no experience with a tankless coil.
8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

Two btu per sq ft for degree difference for a slab

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  • HDE
    HDE Member Posts: 225
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    Probably the shower valve

    Monitor the outlet temp of the coil with different fixtures on,  and if there is a thermostatic mixing valve watch that too.

    More than likely since it doesnt happen when shower is being used, the shower, especially if its a cartridge type is bypassing cold water to the hot side because of a worn cartridge. It does that because the hot side has a lower pressure due to the tankless coil pressure drop.
  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 4,002
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    Tankless Coil

    I'll put my infrared thermometer to work and check the outlet temperature.  What if the temperature fluctuates at the coil?
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
This discussion has been closed.

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