Problem boiler

[Garf255]

Hi,

First time poster here but have been reading the forum for a while to get tips. Thanks so far......

I have a problem that is well documented on here and elsewhere but just not sure of the best way to get it resolved.

We moved house about 5 months ago and have inherited a Potterton Suprima 40

We have been experiencing what i believe to be the common lockout problem where i have to reset the boiler and things kick back in. Today though we have had a new problem where I have to turn off the boiler at the mains, turn on the water & heating, turn the boiler back on, it fires up for about 4 minutes and then the green light flashes. After a bit of research this indicates the boiler thinks it is hot enough. If i turn the water off it goes back to lockout and the process starts again.

All i want to do is put the heating on for a bit!

So, if you're still awake after reading all that (thanks) is this the same issue that is resolved by replacing the pcb? Or is it a separate issue?

If it is, are new pcb boards more successful that reconditioned ones? I can't find anything conclusive that suggests the best route.

Thanks a lot in advance for any help or advice.

Steve

 

[Boilerman2]

The PCB will cost anything from £150 -£200 +Vat and you will need an Engineer to fit it for you, as the wiring loom has to be replaced as well involving going into the Combustion chamber.

It would be cheaper to have a Good gas Boiler engineer out first to check out the Thermistor, the Potentiometer before assuming the fault is a very expensive PCB

In my mind you have nothing to loose by getting someone in and everything to gain!

 

[Garf255]

Thanks boilerman.

So, I got a new PCB and have had it fitted, we also needed to replace the Honeywell 3-way motorised valve at the same time which we did with a new one of the same type.

But now we have a slightly different problem in that the heating will only come on if the hot water is on at the same time.

If we turn the hot water off at the controller the boiler and the heating shut down.

The motorised valve and boiler are working correctly. The wiring to the controller has been checked and is OK.

Any suggestions of what might be causing this latest issue?

Thanks in advance

Steve

 

[londonboy]

The wiring is incorrect. Have whoever fitted the valve return to recheck it.

 

[Garf255]

Thanks Londonboy,

I was thinkiing that might be the case after having a look around on here.

The guy did check the wiring from the wiring box to the new control valve and it was exactly as it was taken out. But thats not to say it was right in the first place.

He did also say that it could be the room thermostat in the lounge and said he would come back with a new one to try.

Cheers

Steve

 

[seco services]

it's not a stat problem as you say you have heating with hw.
sounds more like a fault on the grey wire.

 

[PEDANTICVINDICTIVEMAN]

Thanks Londonboy,

I was thinkiing that might be the case after having a look around on here.

The guy did check the wiring from the wiring box to the new control valve and it was exactly as it was taken out. But thats not to say it was right in the first place.

He did also say that it could be the room thermostat in the lounge and said he would come back with a new one to try.

Cheers

Steve

New one to try, why cant he test the existing one, does he know what he's on with.

 

[Garf255]

He did do something with the room thermastat, I think he turned it right down whilst the heating was on and he said the heating should have gone off but it didn't and thats when he said it might be the thermastat and that he would try a new one.

Cheers

Steve

 

[londonboy]

He could just disconnect the thermostat, that will turn the heating off and prove the stat works.

 

[seco services]

I think he turned it right down whilst the heating was on and he said the heating should have gone off

don't make any sense
as earlier the heating only works with hw now it won't go off.

 

[Garf255]

The heating only comes on when both HW & CH switches on the controller are on.

If the HW is switched off, the boiler shuts down and heating goes off as well.

With both the HW and CH turned on, he turned the room thermastat right down and said he expected the heating to switch off.

Cheers

Steve

 

[seco services]

The heating only comes on when both HW & CH switches on the controller are on.

is that with the hw stat calling or satisfied ?

If the HW is switched off, the boiler shuts down and heating goes off as well.

then either the grey is not being powered or the valve is not moving fully to heating call only.

With both the HW and CH turned on, he turned the room thermastat right down and said he expected the heating to switch off.

how did he prove the heating was still running ?

 

[Garf255]

- is that with the hw stat calling or satisfied ?
I think it's both but not sure to be honest

- how did he prove the heating was still running?
I think he checked the flow at the control valve to see if hot water was being pumped into the heating system.

Cheers

Steve

 

[seco services]

- is that with the hw stat calling or satisfied ?
I think it's both but not sure to be honest

if its both then the heating should work on its own.

 

[Garf255]

Thinking a bit more about it though, the hw out of the tap is hot so it hw might be at temprature. How can I check if the hw is satisfied?

If the HW is turned off at the controller with the CH still turned on at the controller the boiler deffinitley shuts down.

Really appreciate your help with this

Steve