Baxi Solo 3 Pilot solenoid

[KGBGAS]

Hi all,
I got called out yesterday to Baxi Solo 3 50 PF.
Water circuit and pump fine.
Boiler works first time from cold but wont restart 1 minute later if switched off. If it is left running it will heat rads as per normal till preset temp is realised and wont fire up again for approx 6 hours later. Only the boiler neon light is on. Previous engineer replaced temp sensor and O/heat stats and fan and then gave up. I had a new pcb with me and slotted it in but still no luck.
The Manu instructions fault finding guide states if the fan is not working to check temp sensor, potentiometer and continity across pilot solenoid 1.5 K OHM. My test of the pilot solenoid gave me 1.1 K OHMS. Does any body know if this discrepancy can prevent a supply to the fan.

 

[gas4you]

Check the aps as well.

PCB checks whether the aps is in the correct state before allowing the fan to start.

 

[KGBGAS]

Thanks I will check tomorrow. Does anyone know the answer to my original question regarding the pilot solenoid resistance and the effect this may have on the supply to the fan.

 

[namsag]

none at all solenoids will not even get power till the fan has proved the APS

 

[nicknox]

Normally when the pilot solenoid goes on this appliance the pilot LED will light on the display but the boiler will do nothing. But change it anyway, common fault.

 

[KGBGAS]

Thanks for the suggestions guys, will let you know the outcome.

 

[KGBGAS]

Spot on gas4you, it was the APS. Many thanks to you, Namesag and Nicknox for your valuable replies.

 

[corgiman]

I reckon its the air flow switch I do

 

[Agile]

That fault is usually identifiable as a high resistance contact on the NC connections on the APS.

Operating it a few times will often create a variable and sometimes high contact resistance on the APS.

Its important to only measure on a low resistance range where a contact resistance of 2-3 ohms will be seen.

Tony