Myson Apollo 30/50 problem - gas valve / solenoid issue?

[claude2]

I have an issue with my vintage Myson Apollo boiler.
On either central heating or hot water, the boiler won't fire up. The pilot light is on, but the boiler just clicks, but does not fire.
I can hear the pump running. This is the case in both High and Low settings.
About a year ago I had the gas valve changed as the boiler was suffering similar symptoms. I think the solenoid was also mentioned.
Is it likely to be the gas valve again? That would seem strange.
All advice greatly appreciated.

 

[gas112]

Solenoid on gas valve again no need for complete valve

 

[45yearsagasman]

You don't identify your boiler correctly. You maybe referring to the 15/30 Fanfare? If so does the fan run? You mention the pump? There are several components that need to work before the burner will fire. May be the solenoid, but unlucky if it failed in a year. RGI work to diagnose fault.
Is the gas valve button fully retracted?

 

[claude2]

Thanks for replies.
The boiler is a 15/30 as far as I know. It is not the fanfare model and does not have a fan.
Is there a simple way to test the solenoid? And what are the other components that would stop it firing - the gas valve?
Thanks in advance.

 

[45yearsagasman]

There is a simple test, but you require a multimeter to do it correctly.
The solenoid coils can be checked for continuity by disc the solenoid wires and testing across the terminals. A supply test can be done by testing for mains voltage when all is connected and boiler is switched on.
All this should not be undertaken if you are not confident that you can perform these tasks without harm to yourself etc.
I think your boiler is a Thorn Apollo 15/30.

 

[claude2]

You are right on the boiler type, although it is badged as a Myson.
I have got a multimeter - I work in datacoms.
Does the solenoid have to be removed prior to testing?
What values am I looking for?
How is it removed?
Thanks.

 

[45yearsagasman]

I don't think you should be touching the gas valve to do these tests. The fact that you need to ask how to do simple electrical tests leads me to err on the side of safety. No offence intended.

 

[claude2]

None taken. I appreciate your advice, and your caution.
I simply didn't read your post thoroughly. It is a simple enough task to check for 240Vac at the solenoid with the boiler on.
I appreciate a continuity check in situ will confirm the general status of the solenoid.
I asked re a specific resistance value if this was known for a more definite prognosis.
One thing I do not know, however, is to unclip the solenoid!
Thanks again.

 

[mysteryman]

Don't know an actual resistance, but a couple of k would be about it. Open circuit is obviously a failure.

These were the best boilers before the condensing era, especially the later Myson versions.

 

[nickso]

If the 15/30 has a pump overrun switch I would be looking at that. The only thing against that guess is you say the pump is running. Maybe worth checking anyway.

 

[bell824]

sometimes i wonder about some of the advice given out on these forums, a couple of k on a gas valve solenoid REALLY???


45yr you can lead a horse to water but you can't make it drink, great advice as usuall by yourself wish some other folk giving advice had some more experiance!!

 

[claude2]

Have got mains voltage at solenoid.
Solenoid does not show an open circuit - but gives a resistance of 1720 ohms.
Is this the correct value for the solenoid?
This is on a Honeywell V4700E gas valve.

 

[bell824]

Sound pretty high to me,

 

[claude2]

Anyone have a definite on this?
Would like to know before I order another!

 

[claude2]

Is this a high resistance?
Or more likely to be a gas valve issue?
Getting cold here..