Baxi 100 HE

[paulhodson]

My boiler failed to fire yesterday. Had a quick look - no mains light on. Checked fuse - seemed OK so intend to call an expert.

Today it switched on no problem. Green light on and all OK. Later it went off although still on on the timer - no green light again on boiler so presumably intermittent fault - or any other ideas please?

The room stat shows a light to indicate that the heating should be running and the clock is also powered up OK.

Update - switched it on again 2 hours later - and it's working again!

Obviously has a problem though

Thanks

 

[superdupergasman]

Loose wire somewhere on the mains connection into boiler??

 

[paulhodson]

Could be - nothing visible without taking it apart in some way - which I have not investigated - not even sure how to. It has stopped working again by the way

 

[paulhodson]

Update:

The central heating works if the heating and hot water are turned on (Newlec NLC21 programmer). However, once the water is hot enough the system closes down until enough hot water is used to produce demand for the boiler.

Hot water on its own is also OK.

Room stat has been checked by the engineer - operates the Drayton Zone Valve Actuator when switched on and off. (There is another Honeywell motorised valve - presumably connected to the hot water side of the system)

Programmer has been replaced - no improvement so that is not the problem.

Appears to only leave 2 possibilities according to the engineer (who admits that electrics are beyond him really!)

Either there is a micro switch in the zone valve which is failing to send a demand to the boiler when the room stat sends the signal to open it - in which case the head of the valve will be changed - his next stab in the dark- or there is a problem somewhere else in the wiring in which case he will give up!

The system is 4 years old and has worked correctly until now.

Any ideas on this one please? Is it the job of the Drayton valve to trigger the boiler ignition (assuming room stat and clock are switched on) or could this signal come from the room stat?