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Stratman

MB Enthusiast
Joined
Jun 15, 2003
Messages
5,797
Location
Sunbury
Car
W203 C200 CDI '04Estate
The boiler is an Ariston Euro Combi A23/A27 MFFI

The problem is the heating keeps short cycling (On for 20 seconds, off for 30, on for 60s, off for 20 and so on) and while it is heating there is an intermittent rapid clicking noise like a relay chattering which I think is coming from the gas valve.

What is the likely cause and what are my best options?

Any help will be gratefully received.
 
Thanks.

I've had a read and followed the fault finding chart, but it doesn't ask the right questions as is so often the way with these things.
 
I bear good news and bad news:

I have two of these, so would expect to be able to help (good news).

They both break down, but because they are on cover they get fixed and I have no idea what the fixes are (bad news).

Sorry that's not really much help (read no help).

Anyway, Dieselman will know because he knows everything.
 
Probably not what you wanted to hear, but suggest you need a Gas Safe qualified person to look at it for you.
 
If I have my boiler on a low heat setting it does this. I keep it on a higher setting and it ok
 
Sounds as if your spark igniter or NTC heating temperature sensor or fan has gone awol causing the boiler to loop endlessly through its start up cycle. It could be something as simple as a sensor has gone awol and needs replacing. As recommended above you need a good gas safe engineer to sort it. Quite often just like cars certain models of boilers have known weak components which any good boiler engineer worth his salt will check first. The problems tend to arise with intermittent mystery faults.Sounds like yours is fairly constant which should make it easy to pin down.
 
Thanks gents, it's pretty much what I was expecting.

Can anyone recommend a good boiler man in the Mitcham area?
 
I am a gas engineer, Is it firing with cycles ? When the circulating pump spins up they engage a pressure sensor within the boiler, and if it doesn't see a rise, then it will try over and over, till it trips. it can also be the air pressure switch cycling, which will cause relay chatter. when was is last serviced ?
 
I wouldn't be surprised if it's the diverter valve stopping adequate water flow, so the boiler overheats, shuts down, cools and fires up again.
 
It fires and heats with a good flame but after a few seconds the chattering noise starts which sounds like it's coming from the gas valve. As posted earlier it also short cycles. The short cycle jumper link is set to the maximum (2 minutes I think) but the cycles are frequently shorter than that.

Something else I noticed is that the temperature indicator LEDs show it cooling very quickly after it shuts down.
 
I was going to add maybe a blocked filter on the return or heat exchanger blocked and kettling.
It needs looking at properly as any of the above answers can be true
 
To be honest I don't know if it happens on hot water, but it certainly happens on heating.

It does heat the house but with short bursts of heat and the chattering of whatever it is. It doesn't inspire confidence that it will last much longer.
 
Yes thats why I was asking if heating or dhw, I was also thinking blocked or scaled heat exchanger. Could be a pump issue also.
 
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And your suggestion was...

Funny how the least helpful a****oles make the most noise.

No need for such abuse old chap - I expected better from you.



Probably not what you wanted to hear, but suggest you need a Gas Safe qualified person to look at it for you.

My suggestion was perfectly valid - an untrained person should not attempt to repair their gas boiler, primarliy it is a safety issue, but also it can often be cheaper to pay an expert to solve the problem rather than start replacing parts whicih you think "might" be faulty.

If you look back through my posts you will find that where I have knowledge or experience of an issue I willingly share it. That knowledge my not be a vast as yours and my post count may not be as high as yours, but others have found my contribution helpful.

I often also try to inject a little humour into the forum, my quote was from Mr Benn, one of my childhood favourite TV programs

"As if by magic the shopkeeper appeared....... "

I though it very apt in the circumstances. I apologise if it offended you.

I will avoid your posts in future given your response.
 
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All of the suggestions are possible reasons, but with out being there it will make it very hard to diagnose. As people suggested you need a gas safe engineer. Good luck.
 

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