Potterton Suprima 80 Pipes Boiling

[iananddaph]

Hi, I'm having problems with my Potterton Suprima 80, it is 6 yors old and 2 years ago I replaced the original PCB for a new siemens PCB including wiring, all has been fine till about a month ago.
All the lights are OK as per manual.
The boiler fires and runs but after a while it sounds like the flow pipe is boiling and the radiators are very hot regardless of where the control panel temperature switch is.
I have replaced the Thermister sensor thinking the temp couldn't be read by the PCB... no change.
I have also put some new heat sink paste in the Thermister housing.... no change.
I have replaced the PCB again (not wiring).... no change.

Has anyone any ideas?

 

[ChrisR]

Well you've been inside the box so you should be a Gas Safe Registered person. Are you?

If not, you're in the territory where we can't really advise. You'd need to check amongst other things the flue gas analysis and gas pressures.

It sounds like you've been just changing parts in the hope of getting lucky.
It's possible your pump's going slow, so you might as well change that too??

 

[Dan Robinson]

It could actually be the forced draft inducer or the combustion mix ratio venturi. Either could cause the primary output to be too high.

 

[gaswizzard]

Oh dear.

 

[holty]

try another pcb. that might help. if not. try some more thermistors.

 

[glasgowgas]

very common problem with this boiler................

the tickling stick is not entering the giggle valve at the required depth....

try another pcb, that might help





or some more Thermisters

 

[holty]

wrong glasgowgas. this model didn't have a giggle valve. they were phased out before this model.

 

[bell824]

I have replaced the PCB again (not wiring).... no change.

oh come on guys tell the op the correct answer he never changed the wiring thats the reason for it

 

[Dan Robinson]

Come on people... industry pet names are not helpful on a DIY forum.

It is almost certainly the CMRV I mentioned earlier, although some of the 120's used a HAL effect feedback circuit on the PCB's.

Not sure if this got implemented into the later 80's. I doubt it though as Potterton would struggle to fit a light bulb let alone do anything electrically intelligent.

OP, let us know how you get on. Potterton have their ear to the forum grindstone, so you may get some handy feedback.

 

[bell824]

dan the Hal feedback was never issued to these unit's but if i rember right the PITA was around these came about.

 

[Dan Robinson]

Did they use that on the Suprima too?


Christ... you'd think they'd have learnt their lesson from the Puma. There's another thread on here where the poor sod got told by Potterton themselves told him the problem with his heating was the Hot water wasn't turning his boiler on


I mean really... you could make it up!!!!! Oh wait..... They did...

 

[holty]

come on lads. now shouldn't the advice given be restricted to the CC. these are components that can effect the ratio. and a bit dangerous in the wrong hands. shame on you

 

[Dan Robinson]

Normally I would agree, but as the OP has already diagnosed the thermistors, PCB, and thermal paste it is reasonable to assume he is not a total nincompoop.

As long as he doesn't get manometers or gas hydro-osciloscopes involved it shouldn't affect the site owners too much.

I am sure Mod 10 will chip in if he thinks any advise here is OTT or beyond DIY scope?

 

[bell824]

did i not read on another post that cc meant course cowboys?

So does that mean if i go for the same course i can join you guys and be able to give the advice you guys hand out?

Some of you really do know your stuff!

 

[holty]

true dan i suppose the use of a gas hydro-osciloscope. does not matter in the OPs case. as it does sound like the thermo valve could be what is causing the pcb failure. it's hard to say without an onsite evaluation.