Click here to Find a Contractor in your area.
Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit

Tankless Coil

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.
Often wrong, never in doubt.


  • HDE
    HDE Member Posts: 225
    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.
  • Tankless Coil

    I'll put my infrared thermometer to work and check the outlet temperature.  What if the temperature fluctuates at the coil?
    Often wrong, never in doubt.
This discussion has been closed.


It looks like you're new here. If you want to get involved, click one of these buttons!