Combi Heating Problem. How Water Fine!

[gasbanni]

It's a circulation problem, if it had been the pcb why would it work on hot water......you might have a sticking diverted valve. To save money get baxi out.

 

[John Stanwell]

I don't think it is a circulation problem because there is a load of strange clicking from the PCB when heating is on/trying to come on. The boiler has a 3 min anti cycle and the boiler goes out immediately/tries to relight immediately, not after enough time for the temperature to trigger the thermistor/overheat etc

 

[John Stanwell]

The plate heat exchanger (sardine tin) doesn't get warm or the pipes going into it when the heating is on. There's a slight buzzing sound from the boiler when heating on as well

 

[Theweeknd]

The plate heat exchanger (sardine tin) doesn't get warm or the pipes going into it when the heating is on. There's a slight buzzing sound from the boiler when heating on as well

Afaik the plate heat exchanger shouldnt get hot when the central heating is on,

It should only get hot when the h/w is on.

 

[John Stanwell]

I have had the PCB changed as well as the flame probe and lead by a local gas safe gentleman and still the problem continues. He tested the NTC temperature sensor and diverter valve and said he is stumped. He recommended a new boiler but I can't afford one yet. Is there anything weird that could be the problem? What happens is this: burner ignites, flame stays high, after 3-5 seconds it drops. Then goes right down and tries again. But after a while goes out. Happens on heating but on hot water it goes up and down and water not good from taps, only warm. Anyone else had this with this boiler? Thanks for all your patience and help.

 

[MC2012]

Does the red flame failure light appear after 3 attempts?

 

[John Stanwell]

Thanks for reply pal. It varies, just now it has gone to red light after 1 attempt. Reset and same happens.

 

[Daveydub]

Have you perhaps closed off either the flow or return valves beneath boiler?

 

[MC2012]

I’ve had this fault or similar before and it totally threw me, I can’t be 100% sure but I think I adjusted the low- high gas valve pressures cause they were incorrect. There was also an updated overheat stat to solve an issue on these boilers.. has yours ever been changed? I’m not suggesting diy gas works here, just advice to your engineer, maybe as someone else suggested, a call to baxi on a fixed price repair would have been a better idea.

 

[algas]

As an earlier post said check the return connection for a filter, that would cause the fault you describe

 

[John Stanwell]

Thanks again all. I will ask the man across road to check gas pressures. He is usually very good but was stumped, very popular in area. ALl valves are open and magnaclean was cleaned, was badly sludged up. Return valve filter isn;tpresent and was checked when magnaclean was cleaned.

 

[John Stanwell]

Just for info for anyone interested: gas valve pressure was checked and apparently 12.2 millibar which is what should be. Still the problem persists! Very strange. Not sure if this boiler has known problem like this but am annoyed as very cold

 

[MC2012]

And the low pressure? Think I’d be looking at changing the 2 stats

 

[John Stanwell]

Hi, thanks for reply.
Only 1 pressure on this I believe. I looked in manual.
The NTC sensor is correct and so is the overheat

 

[John Stanwell]

Hi, just an update. The cable going to the NTC sensor has a loose connection inside. This was discovered today. When moved/squeezed with grips, the fan runs and boiler fires up. But when let go, cuts out. Is there any way to add some new cable to the black plastic clip/connector that attached to the metal connectors at the thermistor to fix this please?