BAXI WM532rs will not ignite burner

[dave_p_r_b]

Hi all,
I've been cold for several months now. The above boiler failed some time back.

Finally got the money saved to call someone out.

He cleaned up the igniter and now the pilot works as well as it used to. It stays on and seems to be the same size as it used to be.

The main burner wouldn't ignite, so he guessed at the gas valve. He came and installed a new one. Still no ignition.

He tried a new timer. No ignition.

He the suggested thermostat. So I bought one, and put it on. Still no ignition from the main burner. Incidently, I measured the resistance between the two terminals, and even the old one was not open-circuit unless the pot was in the off position.

Any idea's on what to do next? Plumber suggests a new boiler.

I can hear the pump running when I switch the timer to the on position and I know it's supplying 240v to the stat when in the on position. I can hear some form of relay-like click from the gas valve, much as the old one used to.

It was last serviced about 10 months before it stopped working.

Replies would be appreciated.

Oh, how does the pilot light the main burner? Is there a jet of gas from the burner that passes the pilot or something?

Dave.

 

[namsag]

Very simple test . When its meant to be on check at gas valve for 240v if its there (which i suspect it is as you can hear the solenoid clicking) then its still a faulty gas valve .
If there is no 240 you trace it back to where you stop getting it.
This is the most basic boiler you can get and it should only take 5 mins to diagnose if in front of it , you either have a really incompotent guy or are telling porkies and attempting it yourself.
At very worse you have a break or loose neutral as i have seen it happen where the motorised valves have motored over and will bring the pump on but there is not enough power to bring boiler on but simple multi meter tests will show this

 

[dave_p_r_b]

Hi,
I'm not telling lies. I put the thermostat in myself, but left the gas valve to him.

He said if the stat doesnt make it work, he will suggest a new boiler.

I'll try the voltmeter accross the gas valve this evening

There are no motoroised valves. It's gravity fed and has a primtic cylinder.

Dave.

 

[dave_p_r_b]

240v over terminals at gas valve.

David.

 

[namsag]

NEW ? gas valve is feked , needs changing , to be honest all they usually need is the solenoid which is much the same price but takes 5 mins to fit

 

[dave_p_r_b]

>>He came and installed a new one.

>>>>NEW ? gas valve is feked , needs changing

It's exhibiting exactly the same symptoms as the old one. In what way do they fail?

 

[gas4you]

One wonders if it really was a new gas valve.

Did you see the box it came in?

Get him to take it back under warranty and fit another. With 240VAC at the valve terminals it cannot really be anything else

 

[Aquaheat]

Agree with above, providing there is 240V at the terminals then there is no reason for it not to work other than a blockage in the burner pipework to the jet but this would be highly unlikely.

The only other thing i could think of is that the new gas valve has been wound right down and there is no pressure. Get the engineer to do a burner pressure check when the appliance should be running. If he has 240 v at gas valve terminals and cannot adjust the gas pressure up then it is most definately a faulty valve, if he has pressure then the fault will lie downstream of the gas valve.

 

[numpty1]

if this is the gas valve with the grey knob,that you turn to the star sign for ignition and then turn it a bit further for main burner?
just a thought really two valves no main burner same fault new entrant to the gas industry?

 

[dave_p_r_b]

Hi All, thanks for the replies.

It was definitely a new valve, as I bought it from a shop, and it had some form of paper tamper seal over the ports.

I'll call and ask him to do a pressure test. Thanks jonjb.

>> if this is the gas valve with the grey knob,that you turn to the star >>sign for ignition and then turn it a bit further for main burner

It does have a grey knob, I push it in and ignite the pilot using a separate (i guess @ piezoelectric) igniter button. Slowly release the knob and the pilot stays lit. Rotating it clockwise a little shuts off the gas supply.

I know for certain there is 240 accross the gas valve terminals.

Thanks again. I'll post what happens.
Dave.

 

[namsag]

Hit it underneath not very technical but if seating is stuck it may free it

 

[Slugbabydotcom]

More ideas

Wouldnt be the first time that someone hasn't opened the isolating cock properly. Basic I know but still worth checking.
I get about one or two jobs a year where theres a complaint of low gas pressure but someone has knocked the Emergency Control Valve to the nearly off position.
Another possibility is sulphidization, basically an impurity in the gas which reacts with the copper pipe creating a grey graphite looking substance with blocks the pipework.

Whatever, a pressure test will reveal the problem

 

[dave_p_r_b]

The prize goes to jonjb:
"a blockage in the burner pipework to the jet but this would be highly unlikely"

To elaborate...
He took the front off the boiler, and vacuumed inside. The "injector" was then unblocked with a pin.

Looks like it was never the gas valve, or the thermostat but it was a waste of my hard earned cash.

Expect another post soon when I have to change the pump!

Thanks for all your help.
David.