HELP - Boiler problems!!!

[marktoots]

Hi all,

We have a Glow Worm Micron 50FF boiler that earlier this year had it's PCB replaced. Following this we hadn't noticed any problems with the boiler. However, having switched on the central heating for the first time last night I have noticed that the radiators are not getting as warm as they did at the end of last winter. Furthermore, the boiler itself seems to have a significant lag time between the burner shutting off and it re-lighting. I have the temperature dial turned right up on the front of the boiler and it is not showing any warning lights so I am a bit stumped! Can anyone suggest what might be wrong?

Additional information: the pump on the system is a multi-speed unit and is currently set to medium speed.

Pls help as I am getting my ear bent by the wife!!!

 

[gas4you]

Pump needs checking first of all. See FAQ's.

 

[marktoots]

Hi,
Have now checked and in fact replaced the pump. I have also re-balanced the radiators but am still getting problems with the boiler.
The boiler now seems to be "kettling" and when it does the overheat / reset light comes on and I have to switch it off and back on in order to clear the reset. Furthermore, I have noticed that occasionally the boiler fails to ignite, and after a couple of attempts the burner on LED starts flashing and again the only way to recover is to switch the thing off...
I realise the "kettling" is likely to be the result of limescale (although I have previously put inhibitor into the system) but I'm not sure of what is causing the other problem(s).

Can anyone help?

One gas fitter I have spoken to suggested that it could be Air Pressure Switch, or the Temperature Switch or the Thermistor, or the PCB again... To be honest the list was as long as your arm, and I think that he was that actually going to try and sell me is a new boiler. I want to be armed with some insider knowledge before tackling this one!

Thanks in advance.

 

[steve32]

you need to change the thermistor the older thermistors are not compatible with the new pcbs
I asume you had the old style board and you have now fitted the new style board (they were updated about 3 years ago).

 

[marktoots]

Steve
Thanks for that. Yes your assumption is correct the new PCB replaced to old style one, and the engineer who fitted it did not change the thermistor. Guess I'll have to get someone in to do that then before the PCB gets fried...

 

[marktoots]

One further question. Is the thermistor also likely to be causing the ignition lockout problems or is that going to be something else?

 

[Statia]

Change the thermistor first then see how the boiler performs.

 

[steve32]

Yes we are servicing 10 tomorrow that have all had the same faults in the past all have had pcbs and thermistors replaced.
changing the thermistor is not a diy job as you have to take the fan out to release the old lead and fit the new.

Hope this helps

Steve

 

[Agile]

Hi,

One gas fitter I have spoken to suggested that it could be Air Pressure Switch, or the Temperature Switch or the Thermistor, or the PCB again... To be honest the list was as long as your arm, and I think that he was that actually going to try and sell me is a new boiler. I want to be armed with some insider knowledge before tackling this one!

Thanks in advance.

I am very pleased that he did not tell you free of charge what was wrong with your boiler!

It is perfectly fair and reasonable for him to charge for utilising his skills.

We charge from £84 to come and diagnose boiler faults and we never make free visits!

Tony

 

[kevplumb]

We charge from £84 to come and diagnose boiler faults and we never make free visits!

and we do like a bit of free advertising as well

 

[Agile]

Those who want to get free fault diagnosis visits would not see it as advertising when I state that we dont make any free visits.

I would say to them why do they think anyone should do work for them free of charge!

Tony

 

[Statia]

changing the thermistor is not a diy job as you have to take the fan out to release the old lead and fit the new.

I disagree. It is a DIY job as I changed the thermistor (and the phial it sits in) myself in my GW Micron. I didn't have to touch the fan.