Baxi luna 310

Steve_210

Changed main board and air switch on this Two to three weeks ago.
It is not used for hot water
If I jump out of the micro switch assembly on the pressure differential, Pump starts fan proves and boiler fires I'm tricking the boiler into thinking there's a call for hot water and I get heat no problem but obviously I can't leave it like this
There is no external thermostat, jumper appears to be correct but I cannot get a call for heat pump does not even start.
I have the manual
Any advise

superdave

The TT on Baxi 310FI uses 120V make sure you have wire rated for that and if you are running a single zone you need a relay to drop the 120v power from hitting your t stat. Also try putting a jumper on M block 1&2 to see if boiler fires up and when you installed new PSB board did you put brown jumper back in on I think it is A3 set of pins??

Steve_210

Steve_210

Pics

Steve_210

Thanks Dave This unit looks a bit different the thermostat jumper is between four and six on a separate board
I did try jumping out 1&2 last night nothing
Small board has 110 coming in but no 24 on the thermostat side
I tried running separate power supply to the pump as a temporary measure but the pump light was flashing, put everything back together and it worked for a while and now has gone down again almost sure the small board needs to be replaced.

superdave

Pull off small board and put back brown jumper and try 1&2 again if that work might be faster to get a single relay box. Also check pump wire to make sure its not kinked so when you put up panel it brakes circuit.

Steve_210

Thanks pretty sure the pump wire is OK because it works when I create a dummy call for hot water
Well Troy what you said

Steve_210

A friend of mine had a small board we changed it out solved the problem thanks for your help especially on a Sunday.

superdave

No problem