potterton prima f50 problem

[dotto]

Hi guys. I have a Potterton Prima F50. Normally when there is a call for hw or ch i have the flame going off after the boiler has run for 5-10 minutes. Then i hear the click of the fan attempting to switch itself on several times before the boiler relights again ( i suppose the boiler goes off because the thermostat reaches the set temperature and when the boiler temp drops it relights again and during that time the fan goes on and off probably because it is still receiving the call for heat.). Last week though, the boiler went off after 5-10 min but the fan carried on running non stop for about 20 min while there was still a call for hw, but the boiler refused to relight. I tried the reset button underneath the boiler but nothing happened. I reached the programmer and switched the hw call button on the programmer ( which i leave it on all the time) off. That stopped the fan running. I switched the hw button on the programmer back on and the boiler relit. Since then i have had no problems but this morning that problem occured again and i did exactly the same thing that i did last week and it worked again. I know it is not normal and before that trick stops working i would like to know what might cause that erratic behaviour. Can anyone point me in the right direction? Thank you very much for your time. BTW i have had a contract with BG for the past 5 years for servicing it and cancelled it last summer.....how typical

 

[Agile]

For such a simple boiler a BG contract is not good value.

You might have the PCB, fan or gas valve fail at any time during the boiler's life of aboiut 15 years. An independent should deal with any of those for less than £200. On average I would expect 2-3 faults in 15 years costing with an independent about £600 and hopefully a few services at £55.

With BG you would be paying about £2700 over that time which is enough to replace the boiler twice over!

In this case I expect its a PCB fault but I would check everything else first as it may be a safety device associated with the fan and thats much cheaper.

Tony

 

[dotto]

Hi Tony and thanks for your ever good professional advice. If the problem lays with one of the three components mentioned by you, why does the boiler fires up again after i have switched off the hw call at the programmer and switch the hw back on? Could please tell me what sort of tests i can carry out to eliminate them? I am a plumber and good with my hands and a multimeter.............that goes without saying that a would not touch a gas valve! It never happens at start up but in the middle of the day. I think i can eliminate the pump as i live in a terraced house and the rads downstairs do get hot quite quickly. The boiler stat is on mark 3 as it has always been. Thanks again for your time.

 

[45yearsagasman]

Great advice Tony,but what about all the other system components?Pump,motorised valves,rads and valves or do they not count as breakdowns.

 

[dotto]

Hi.the mv are working ok because when there is a call for hw or ch they opon and I can feel hot system water going through the respective hot water cylinder or to the rads.....I can feel the pipes getting very hot. The pump also works ok despite getting very hot.....but as I live in aterraced house and the rads on the ground floor do get hot, I suppose that tells me the pump is doing it's job.

 

[dotto]

Can anyone please tell me how to check the pcb and fan with a multimeter? And could anyone also send me a link to download the servicing instruction please? Thank you all very much for your time

 

[Agile]

That last request would involve gas work and as I said before we are not permitted to advise or encourage a DIYer to do gas work on this forum.

Tony

 

[dotto]

Hi Tony i have found a schematic of my boiler and they show that i should check for 240v between T2 and T3, if no 240v then electronic board fault. Since that does not involve the the GV nor the flue i think it is safe for me to check for it.......if GV or fan require attention then i ll call the corgi man. One more thing....................as mentioned in my first thread, the fan whirrs non stop and requires me to switch off the hw demand at the programmer for the fan to stop and that is one problem to be assessed as we have already talked about!............ Also ( not at start up though) after the boiler fires up, it stays on for about 5-10 minutes before the Gv shuts off ( i believe that is to allow the boiler to cool down) and the fan enters a cycle of on and off clicks ( i d say about 15 times) before the boiler fires up again. Is that normal for the fan to go on and off as many times? Does it behave like that because the fan does not know that the boiler has reached the set temp and therefore makes attempts to run?.....or is that another erratic behaviour? Thanks again.

 

[Agile]

You can work on the PCB , thats no problem on your boiler as there are no gas settings on it unlike some.

It certainly sounds like a PCB fault but over the internet no one can be 100% sure and its a more expensive part if it were wrongly diagnosed.

I dont know what T2 and T3 do without looking up the boiler details.

Most plumbers have gas registered friends whom they liase for gas jobs.

Tony

 

[dotto]

Hi Tony and thanks again for your input. Yes i do know people who are Gas Safe but they are not necessarily good at explaining things or they do not want to take the time, i suppose. While on this site,on the other hand, you only find professionals who do not mind to take the time and to share their knowledge with people keen on having a go themselves I have learnt an awful lot of stuff from people like yourself on this forum.Thanks again and have a good day.

 

[dotto]

BTW, i have found a company on line that sell reconditioned boiler pcbs.............and i could get mine for £44. Would you go for a reconditioned one?Ta