Ariston boiler problem

[garethv-w]

Hello,

I'm after some advice on a domestic boiler problem.

It's an Ariston Genus 27 MFFI combi that was working fine until a couple of days ago, nothing has been changed prior to it acting up.

Central heating works perfectly. The problem is that when a hot tap is turned on, the boiler fires and the water runs hot but after 30secs or so the burner goes out and the water runs cold (this is without touching the tap). After 10secs the boiler then lights again and the water runs hot for another 30sec before going cold again.

I'm guessing the flow switch is working as the water runs hot to start with and I assume the diverter valve is also okay as again I do get hot water. Is there a hot water thermostat that isn't sensing quickly enough or do I have the wrong end of the stick? I'm competent to replace components (famous last words) but I need some help re diagnostics.

You should've heard the wife screaming in the shower this morning, soap in her eyes and freezing water coming out of the shower head. Anyway, you get the picture. Any advice would be much appreciated.

Regards,

Gareth

 

[Agile]

There are many possible causes of your problem but to narrow it down its necessary to do some tests.

Can you measure the temperatures of the flow and return pipes to the main heat exchanger?

It might be a blocked secondary HE although your 30 secs is a bit long for that. It might be a temperature control fault. It might be an APS/fan/venturi althouth as thats a gas safety issue I am reluctant to give you detailed instruction as I dont know if you are competent to work on those parts.

Diagnosing boiler faults is not so easy without some skills and test equipment.

Tony

 

[garethv-w]

hello,

thanks for the advice. i was hoping the symptoms would point to a specific component (non gas related). reckon it might be time to mortgage the cat and cough up for a professional to sort it out.

thanks again,

regards,

gareth

 

[Agile]

In Bristol you cannot do any better than to call Chris Hutt !

Email him from his profile.

Any difficulties then email Doitall from his profile and he will pass the info on.

Tony