Baxi Luna 310

Needhelp

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

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?

Steve Whitbeck

diaphrams

If it has the diaphrams replace them. Stupid design.

Tom_133

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.

Alan (California Radiant) Forbes

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.