Baxi Solo 3

[stem]

I have a natural gas Baxi Solo 3. Occasionally, when it cuts in the fan comes on and off at approximately 1 second intervals. Sometimes if the fan runs for long enough, the pilot light will come on and then go off as well. This happens between 2-6 times until eventually it fires up and will then run OK. This has occurred since the boiler was installed but only noticed about once a month. Now after 5 years it is happening most days. At each service I have mentioned it and the Corgi engineer has checked the air pressure switch and cleaned the pipes to it, although in fairness the fault has never appeared whilst he was present.

About 18 months ago, the main PCB failed (Fault with the part that controls the pump) and a new one was installed. I had hoped this would also cure this fault, but it hasn't.

The "boiler on" light remains steady whilst the "fan running" light and sometimes the "pilot" light is flashing on and off so the switched live from the motorised valve microswitches (S Plan) appears steady.

Anyone come across this before, should I investigate this further or just live with it until it fails completely?

 

[gazthepottertonengineer]

this is a fairly common problem with this boiler and can normally be resolved by removng the restrictor in the flue behind the fan !!

if this does not resolve it i would look at replacing the air pressure switch checking the platic elbow and hoses from this to the fan are not split

 

[stem]

Thanks Gaz, will book annual service now and ask to have restrictor removed.

 

[stem]

Sorted eventually. Took Potterton 4 visits to cure, replaced pressure switch, PCB, Fan, Solenoid valve and finally temperature transmitter. that cured it.

 

[DarkInferno]

Sorted eventually. Took Potterton 4 visits to cure, replaced pressure switch, PCB, Fan, Solenoid valve and finally temperature transmitter. that cured it.

PCB? possible but you have had the fault with 2 seperate PCB's before, so No.

Fan? No. It either spins or it doesn't, it doesn't have any decision over the matter. The Air Pressure Switch Does that bit. It can spin too slowly when the bearings start to go but its normally as noisy as hell when that happens, which you didn't mention.

Solenoid Valve? On the gas valve? But you said the pilot was lighting before it went out. (Possibly slow to operate, but unlikely). No.

Temp Sensor? Possible if it is sending erratic readings, but I don't think that would give you the sympoms you gave (specifically the Fan going on and off in a 1sec cycle)

If it's fixed thats great but I can't see a case where any of the parts changed would effect cure on the sympoms given. *shrug*

 

[stem]

The temp sensor was found to be the problem. As you suggested it was giving erratic readings. The engineer tested the water temp with boiler on max & temp of water leaving the boiler was less than 60 deg when the burner cut off. It appears that the sensor was telling the controls heat was required, then it wasn't, then it was etc., switching the boiler on and off at random.

Turns out replacing the fan wasn't anything to do with the fault, just that it was noisy.

 

[meldrew's_mate]

"Stem said"

Turns out replacing the fan wasn't anything to do with the fault, just that it was noisy.

And the little rascal found and fixed the cracked air pressure pipe elbows wlile he was at it.