Potterton boiler failing to fire up.

[TandyMan]

Potterton boiler failing to fire up.

Hi

I have a Potterton (80? It is not a combi boiler, 5 years old) standard wall mounted gas boiler with a balanced flu.

When the heating system (water or room) calls for heat, the boiler starts the ignition sequence.

The fan starts,
Two or three clicks in close succession.
Pilot light starts.

And then nothing, there is a roaring noise from the fan, but boiler fails to start. There are no further clicks.

And the problem is intermittent; the boiler fails more often when it/water is already hot.

The heating system has been installed for about five years without modification.

Thanks for any advice.

Chris

 

[GforceJames]

Sounds like a flame rectification issue, could be dodgy electrode/lead or defective pcb.

You need to check to see if power is going to the main burner solenoid on the gas valve though to eleminate a faulty gas valve.

James

 

[hi-spec plumbing heating]

had one exact same problem would fire on about the six attempt.
that had a faulty ignition module on pcb

 

[TandyMan]

Thanks to GforceJames for pointing me in the direction of 'flame rectification'.

Unfortunately the boiler is still playing up.

I did a quick Google and found that 'flame rectification' requires a good earth and the wire from the electrode is very fussy (you want it to be as far from any metal work as possible!).

Therefore, I cleaned and re-made all the earths, cleaned the electrode wire and did a long test (from cold to system fully hot water/heating) all worked.

I then raised the tray containing the PCB and pressure switch up to the boiler (Previously it was hanging down at 45 degrees) and the boiler immediately started to play up, i.e. Pilot light on, but main burner is not burning.

I then lowered the tray containing the PCB and pressure switch, all worked fine, did extended test, all worked fine.

Again, I then raised the tray containing the PCB etc. and the boiler started to fail again.

I have now left the Tray lowered and all is working just fine.

I have checked all the connections (of which there are many) and wires, none of the wires are damaged or strained in any way, the PCB is clean and all the joins look wet (not dry).

What is going on?

Thanks in advance for any help.

Chris

 

[Scarum]

Hi, does the boiler ignite OK when you demand hot water only and not heating? If so you might need a new actuator. I only replaced my actuator yesterday.

 

[Agile]

It sounds like a Profile or similar!

Raising the PCb tray often traps or kinks the air tubes to air pressure switch.

Replacing or rearranging them should cure this fault. ( If thats what it is! )

Tony

 

[TandyMan]

Hi, does the boiler ignite OK when you demand hot water only and not heating? ...

No, we have two room thermostats and one hot water tank thermostat, it does not matter which one calls for heat, the boiler still fails when the tray containing the PCB etc. is in the correct position, i.e. up against the bottom of the boiler.

When the steel Tray containing the PCB and Pressure switch is lowered, then everything works normally as far as I can tell.

It could be:
- A lose/broken wire, but I have checked all the wiring.
- A component that is / has become heat sensitive. I don't know which components would be heat sensitive in a boiler, but the boiler will always fire up from cold. As the boiler gets hot the main gas burner will turn off, but the pilot light will stay on. If the system in working correctly and the system as whole is up to temperature then the pilot light goes out (as expected)

Any ideas appreciated.

Thanks Chris

 

[TandyMan]

It sounds like a Profile or similar!

Raising the PCb tray often traps or kinks the air tubes to air pressure switch.

Replacing or rearranging them should cure this fault. ( If thats what it is! )

Tony

Thanks for your advice Tony, I have re-arranged to air tubes to the pressure switch (one clear, one red) to make them less kinked, unfortunately the fault is after the air pressure switch in the start sequence. I don't believe that the pilot light would light if the air pressure failed?

Chris

 

[TandyMan]

It sounds like a Profile or similar!

Raising the PCb tray often traps or kinks the air tubes to air pressure switch. Tony

I have spent some time thinking about the above, if the pilot flame was not detected, then the spark generator would carry on sparking, which it does not, therefore is the air pressure measured after the pilot is alight?

What is the ignition sequence of a potterton PROFILE PREMA 80E?

Thanks

Chris