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

Baxi Luna 310

Needhelp Member Posts: 1
HELP!!!!!!! I have a Baxi Luna 310 I wall hung boiler. I get hot water when I use the faucet but the boiler will not run when the heating zones call for for heat. I jumped out the TT connection to eliminate any Tstats or the XX conection on the relay. not sure what to check next. thanks for any help.


  • Tom_133
    Tom_133 Member Posts: 820
    Oh my memory

    Is the 310 the boiler with diaphragms that activate the micro switch, or is yours newer with the control on the front jacket?
    Montpelier Vt
  • Steve Whitbeck
    Steve Whitbeck Member Posts: 669

    If it has the diaphrams replace them. Stupid design.
  • Tom_133
    Tom_133 Member Posts: 820
    Thanks Steve

    I thought thats what it was but didn't want to sound like a fool.

    So to the homeowner, if you look in and to the left when the boiler starts hot water production there is a round brass fitting around 5" in diameter with a small chrome rod that comes out and pushes against a micro switch that tells the boiler to fire for domestic hot water. Same is true for heat, but the diaphragm on your boiler is not pushing the chrome rod out enough to engage the micro switch. The diaphragms are cheap and easy to replace.
    Montpelier Vt
  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 3,243
    edited January 2013
    Micro switch

    And if the chrome rod is pushing out and engaging the micro switch, the diaphragm may be fine and it can be the micro switch that is bad.  I just replaced one last week.
    Often wrong, never in doubt.
This discussion has been closed.