Problem with Ideal Concord CX

[RobbieHill]

Hi all, I'm having problems with my boiler.

It fires up fine, will run for about 30 mins then all gas will cut off causing the burners and pilot to go out. Which I assume is the high temp stat doing its job? What I need to know is why is it over heating?

I have a feeling the themostat isn't working. When you turn the dial, now matter what setting you have it on (1-6) the burners still 'run' the same. I'm assuming when the boiler reaches the temp setting its set at, the thermostat SHOULD turn off the burners and leave the pilot on before the high temp stat has a chance to shut it down? Would this be a faulty potentiometer or could it be the sensor? Or both?

Any help appreciated!

 

[diamondgas]

It's not just a dodgy pilot or t/cupl is it? 30 mins doesn't seem that long for a cx to get up to max temp...? What model is your boiler? What light is on as fault?

 

[Billy Bob Bob]

call a gsr engineer it could be many things

 

[RobbieHill]

Thankyou for replying. the thermocouple has recently been changed and is working fine( if electric is turned off the pilot will stay on) it is definately overheating as the overheat reset has to be pressed to re-light pilot. It may stay on for longer than 30 mins but it all depends on how long its been since it was last on!

Its a concord cx340 and is ancient and has no lights!

 

[villa_tom]

Maybe time for an upgrade. As gasman says get a GSR engineer in to have a look.

 

[diamondgas]

Thankyou for replying. the thermocouple has recently been changed and is working fine( if electric is turned off the pilot will stay on) it is definately overheating as the overheat reset has to be pressed to re-light pilot. It may stay on for longer than 30 mins but it all depends on how long its been since it was last on!

Its a concord cx340 and is ancient and has no lights!

Your first thoughts regarding temperature thermostat seems the more likely route to take but as gas man says ... call someone registered out to take a look, it ain't something you want to be messing with IHO

 

[RobbieHill]

Hi, thanks for your help before. I can't afford to upgrade the system as I have been quoted 10k! I have changed the boiler thermostat and the sensor yet the burners will still not turn off. The thermostat 'clicks' as if it is sensing it has hit the set temperature but the burners continue to run until it overheats.

Could it be the gas valve that controls the burners is jammed open? Or maybe a faulty PCB?

Any help appreciated

 

[diamondgas]

You could be on the money once again Robbie .... easiest way to check that out is to cut the power to the boiler (Not Literally) and see if the burner goes out straight away! I've known of gas valves to stick or open/close slowly. By turning off the power to the boiler you'll know whether the cause is electrical or mechanical.

 

[diamondgas]

If it is the gas valve you will need to get someone qualified to replace it as there are perameters that will need checking/adjusting.

 

[RobbieHill]

Thankyou for the quick reply! When the power to the boiler is turned off the burners go straight out ( this is how we have been turning it on and off without having to relight the pilot). Would this suggest it is the gas valve causing the problem?

 

[diamondgas]

Less likely to be the gas valve, more likely one of the boards depending on how your boiler is set up. The thermostat should interrupt the power supply to the gas valve when shut off. What your describing seems to indicate that this is not happening. Possibly a fused relay on the board, but that's a guess! You'll need to get someone familiar with your boiler, it's a commercial appliance, to trace the cause.

 

[RobbieHill]

Thankyou once again, ive ordered 2 new boards will see how I get on with those.

 

[diamondgas]

Well if it ain't any of those then you'll have re-built the bleedn' thing!! LOL Well all except the gas valve!! I'd imagine they aren't cheap parts ...

 

[RobbieHill]

Got the thermostat assy kit for £50 and both circuit boards come to £160 so not to bad...