Alpha 240P boiler

[Jason C-P]

Hi all,
New to this forum stuff - be gentle.

My 240P boiler has just started playing up. When calling for hot water or central heating the boiler fires, makes the air pressure switch - runs for about 5-7 seconds, looses flame and goes back into a purge (orange neon comes on).
Changed the air pressure switch and to my dismay - still no joy.
Please can any of you advise me on how to find the fault.
Thanks,
Jason C-P.
Kent.

 

[ChrisR]

It's probably a gas/combustion related thing so can only advise you call a Corgi regd bod to service it.
You could check that the system flow switch (on top of the diverter valve) is staying pressed, though.

 

[Jason C-P]

Hi Chris,
What does the flow switch/diverter valve look like?
Thanks for answering.

 

[Jason C-P]

Dear all,
Still struggling on this one. Still feel that it is more a controls issue than combustion-might be wrong. Wondering if the brand new air pressure switch is at fault? Is there a way of by passing this momentarily to see if I still loose flame?
Rather not call out the Corgi boys at the moment- that's the reason for joining the forum

 

[Rob]

The flow switch that Chris said about sits on top of the diverter.

If the Orange light stays on then definatley a job for a Corgi.

A proper service should cure it though.

 

[cowley]

You say that you have replaced the air pressure switch on this boiler yes?.
By doing so you have disturbed the seal.
on this make of boiler the symptoms you describe are usually to do with a dirty venturi.
You will need someone registered to cure this, in the mean time feel around the inner casing and listen for any sucking air noise to make sure you have resealed the inner case properly.

 

[Jason C-P]

Hi Cowley,
Blew both tubes through and inspected flue. Have already checked seal and replaced all four captive clips for the screws as the old ones were rusty.

Still no joy.

Anyone else got any ideas/pointers please?

 

[cowley]

Do you mean you blew both tubes coming from aps?.
That isn't going to clean the venturi.

 

[Jason C-P]

Hi Cowley,
OK - how do I clean the venturi then please? Where is it situated?
Thanks.

 

[cowley]

You really need a rgi to do this job but if you insist on doing it yourself and seeing as you have already entered the section of the boiler where you shouldn't have.

He's read it, and we don't want to encourage others for the reasons you stated, so I've removed your "dangerous" advice. Mod10

 

[Jason C-P]

OK. Thanks for that - I'll have another look tomorrow and assess the job as this is obviously now a combustion space strip down. From your description I need to get parts in as during the strip there will be items that cannot be replaced once removed, like the spire clips.
I really appreciate your help Cowley and thank you for your time and advice based on your experience - I must stress that although I'm not Corgi registered, I am a combustion engineer in the Power industry (bigger boilers)- so I'm well aware of my boundaries.
Thanks again for your time and help.

 

[Jason C-P]

Hi to all,
Many thanks to you all for you valid assistance. It was a blocked venturi after all. Replaced rather than clean - cost £18.00. Also needed a flue clamp. Old one rusted and broken. Tested for a gas-tight seal - OK. Cleaned burner assembly whilst I was in there.

Boiler like new again.

Thanks again every-one.