Potterton Suprima 60L sequence onans off??

[RussH]

Hi

I have a 4 year old Suprima 60 L . My system is open vented fully pumped and has a Honeywell mid position Y plan valve.
My question is regarding the Control Sequence and normal way of running.
The start sequence starts as stated in the manual. However the burner only stays on for about 3 mins it then goes off (not locked out ie does not need resetting) the pump remains running (overruns for the designed 2 mins) The pump then stops just for a second or so... and the sequence starts all over again. The system runs like this until the room stat is satisfied. I have tried higher and lower settings on the boiler temperature control but if make little difference ( when temp control is lower the burner goes off after say 2 mins or so). Is this normal or should the boiler run continuously until the room stat stops it?
The above sequence also happens if hot water only is selected.

 

[baxpoti]

First thing to do is measure the flow temp at the boiler.

 

[RussH]

First thing to do is measure the flow temp at the boiler.

Thanks for your quick reply. What temperature am I looking for? (PS i am not a heating engineer i just would like to unerstand the prob before calling out anyone) Thanks

 

[RussH]

First thing to do is measure the flow temp at the boiler.

Thanks for your quick reply. What temperature am I looking for? (PS i am not a heating engineer i just would like to unerstand the prob before calling out anyone) Thanks

I have also tried all three flow settings on my pump does nt change the sequence problem.

 

[baxpoti]

The control can be set between 'Off' and 'Max' which corresponds approximately to a temperature range of 55 °C to 82°C

 

[RussH]

The control can be set between 'Off' and 'Max' which corresponds approximately to a temperature range of 55 °C to 82°C

Thanks again. I'll try an get a digital contact thermometer.

 

[RussH]

The control can be set between 'Off' and 'Max' which corresponds approximately to a temperature range of 55 °C to 82°C

Thanks again. I'll try an get a digital contact thermometer.

The temperature is 64c when the boiler goes off... after two mins of pump overrun the temp is down to 56c and the start sequence kicks in. Any ideas?

 

[baxpoti]

Do you have one (which changes colour) or two seperate LEDs next to the thermostat knob?

(In either case its probably a PCB problem)

 

[ddk]

i am 99% sure this is a PCB problem. i have had this issue twice before, and after replacing overheat stats, roomstats and checking the pump a million times i went for the PCB. the pcb cycles the burner and pump, often only enough for the radiators closest to the pump to reach temperature. The PCB is about 200 quid and comes with a full wiring harness so i would advise a one-off charge from british gas, as it would be the cheaper option. also, if youre replacing the PCB it may be worth checking the gas valve- if you look at it, it will have a 3 digit number printed onto a black plastic part of the valve (around the solenoids). if this number is 401 youre fine, but if it is 411 it may spike out the new pcb (should the gas valve fail in the future) and result in having to fork out for a new gas valve AND another new PCB

 

[baxpoti]

if this number is 401 youre fine, but if it is 411 it may spike out the new pcb (should the gas valve fail in the future)

Where did you get this info from?

 

[superdupergasman]

if this number is 401 youre fine, but if it is 411 it may spike out the new pcb (should the gas valve fail in the future)

Where did you get this info from?

hints and tips on the BG laptop

 

[ddk]

experience

 

[ddk]

when you have changed a PCB for a very large, ill tempered customer and then have to explain to him that he also needs a new gas valve, you tend to remember these things

 

[powell30]

Went to one the other day.....almost certainly the pcb.....it fires, works for a couple of mins and shuts down then repeats......if you already have a 'new' style board in just replace the pcb cartridge and leave the harness in/on

 

[robertbentley]

Did this one get fixed ? My potterton 60L is doing exactly the same thing. I have the single LED board, I think it was replaced 3 years ago...