Boiler only runs for 35 seconds every 4 minutes

[TORMULA]

Still having problems with my heating.

The boiler is only firing up for about 35 - 40 seconds every 3 - 4 minutes.

Its not exactly the same everytime sometimes its 45 seconds.

Its been fine for the past few days but today has started playing up again. The result of this is that the rads only get luke warm.

Any ideas?

Thanks

 

[wnjswozo]

need more info/make of boiler,type of boiler

 

[TORMULA]

Its a Potterton Suprima 50L about 6 years old.

Other posts seem to suggest the pcb as it indicates "Boiler Temperature Control Satisfied'

Is there a way of testing the sensor? and is there an easy way of telling what version pcb I have? i.e. do I already have the later wiring?

Is it worth cleaning the contacts on the pcb?

The heatings working OK at the moment so its very intermitent.

I replaced the pump about 3 weeks ago and that seems to be working OK

 

[Renewable M]

maybe the heat isnt getting away from the boiler. is the system balanced correctly?

Boiler is turning off on it's internal stat before the heat has an opportunity to get around the rads.

Superficially, it points to a circulatory issue.....possibly

 

[Puddle]

Well think you are going to get someone in to check
do not think pcb as would go to reset
possible air pressure switch problem and maybe fan slowing when gets hot
also could be gas valve sticking,all common faults with suprima

 

[REDSAW]

Well think you are going to get someone in to check
do not think pcb as would go to reset
possible air pressure switch problem and maybe fan slowing when gets hot
also could be gas valve sticking,all common faults with suprima

thats my thought too,
the fan or venturi, or t/stat prob.
try a squirt of wd in the fan bearing and monitor it.

 

[TORMULA]

Thanks for the replys.

Dont think its a balance problem, although I'm sure it needs to be balanced, as I still have the problem if I switch to Hot Water only. I dont know how to balance the system without any heat to start with, at the moment all of the rads are on/open but could be another circulation issue, dont know where to start looking though.

It does sometime sound like there could be air in the system somewhere but I've no idea how to get it out, I've vented the pump several times.

I have an odd valve that I dont know what its suposed to do, it sits between the output of the pump and the return from the hot water cylinder. I assume its some sort of return to the boiler, if its open i cant see that and water would pump though either the cylinder or the rads (photo below)

The house was empty all over last winter with the heating off but not drained as far as I could tell when we moved in.

Give me electricity any day!

 

[Deleted member 261]

was the water clean when you changed the pump?

 

[TORMULA]

Yes water was very clean, I've moved a ground floor radiator too and that was also very clean.

 

[Deleted member 261]

Pump right way round?
Valves open fully?
pump settings on full?
does the water on the flow get hot and how far?

 

[TORMULA]

Thanks for your replys.

Pump is right way round and all the valves are open.

Pump is now on full but doesnt seem to make any difference if its set to 2 or 3.

I had a go at balancing the system and this seemed to make a big difference, we've had heat for the past week.... until yesterday when the same problem came back again.

I'm sure theres air in the system somewhere but I dont know how to get it out, tried bleeding the rads again but they are all ok.

Vented to pump a couple of times, still no difference. Gave up, went shopping and when i came back it was working again

Thinking of putting the old pump back on as that is suposed to automatically vent.

Just put up anothet couple of posts about a cold rad and a trv question.

Is it worth getting a BG contract and then letting them come and sort it out?

 

[newbie1]

why get bg when there are prob a shedload of gsr engineers in your locality???

 

[TORMULA]

Because I can get BG cover for around £20/month and wont have a big bill in one hit.

 

[newbie1]

20pound a month 240 a year thats a fairly big bill
2 years nearly 500.00

 

[TORMULA]

Thanks for everyones help with this.

Turned out to be the main pcb. I tried changing the thermister and overheat sensor and although this got it running for about 90 seconds it still wasnt right.

Research around the net suggested that the newer pcbs sometimes suffer from the problem where they think the system is hotter than it is.

Anyway new pcb has it running properly.

Just have to try and cure the one rad that only gets warm while the others are hot, I'll try balancing the system again later and then investigate the pipework.