Boiler cycling on and off

[smn159]

I have a Potterton Profile boiler, running a gravity heating system, so that the heating requires the hot water to be on as well. I've recently fitted a CM927 controller, and all has been well for a couple of weeks.

However, the boiler has now started cycling on and off quickly when it reaches temperature. Sometimes the main burner lights, it runs for a few minutes and then the main burner switches off for a second and then on again continually. At other times, it seems to work OK - i.e. fires up and runs until the room temperature is met and then switches off until the temp drops.

Any ideas on the likely causes?

[Frosty R1]

Possibily the PCB is at fault..maybe a loose solider joint inside. Thats what was up with our Potterton Prima40

New PCB boards are quite expensive.I would get in a plumber to confirm though.

[4sure]

ours did similar, in the end after trying everything else it was found to be a circ pump in the loft which was working intermittently.
Maybe worth a check?

[james12345]

Frosty R1 said:

Possibily the PCB is at fault..maybe a loose solider joint inside. Thats what was up with our Potterton Prima40

New PCB boards are quite expensive.I would get in a plumber to confirm though.

Had the same with our Prima 60 - replaced circuit board (around £120 for a recon unit) which lasted about a year. Ended up replacing 3 capacitors for approximately 63p from Maplins to sort it properly.

Obviously, I mean that my Gas Safe plumber came and did it for me.....

[smn159]

Thanks guys. I have a local guy booked in next week to have a look at it so I'll post up what he finds.

[NST]

I had been suffering from the same issue (profiler 80e), turned out to be the gas valve..

The cycling could also be the Fan is on the way out.. google profiler fan cycling

[smn159]

Turned out to be the PCB, as suggested. Apparently the heat of the boiler kills them over time.

All sorted now (hopefully)

[Frosty R1]

smn159 said:

Turned out to be the PCB, as suggested. Apparently the heat of the boiler kills them over time.

All sorted now (hopefully)

Result, Glad you found the cause of the problem its normally what goes on them.

Other than the PCB going over time I was told that these boilers are pretty bullet proof.