Baxi 105e - Intermittent central heating failure

[richandjo]

The hot water neon remains on after demand for hot water has ceased. There are no dripping taps or anything that could be calling for the hot water supply.

When it stays on, it obviously prevents the central heating from functioning, even though the boiler is not actually fired up when the neon is illuminated, other than when there is a real demand for hot water, such as a hot water tap being run.

After the hot water has been run, the hot water neon sometimes goes off, thus allowing the central heating to fire up, with its associated neon then glowing.

Our Corgi man struggled to find an answer and thought it was the temperature sensor, so he changed it. However, not long after he'd gone, the same problem returned.

Any ideas as to why the hot water neon would be on when the boiler's not even running (for hot water or central heating) and why it would then go off (although I guess it should do!) after a tap has been run - but only sometimes?!

Baxi, themselves, seem puzzled but have offered no solution.

Any help would be appreciated!

Thanks a lot.

 

[baxpoti]

Is your dhw microswitch sticking?
Does the plunger return after you switch off hot water?

 

[richandjo]

Thanks for the reply.

I'm the end user, not an engineer, so have to say that I don't know what a dhw microswitch is or where I would find it to see if it were sticking. Same goes for the plunger question, I'm afraid. How would I tell if the plunger returns when I switch off the hot water and what is the significance of that?

Please excuse my ignorance.

I do know that, if the hot water neon is off, the heating will come on and also - as a general rule - when the hot water neon is 'stuck' on (without the boiler firing), a quick opening of a hot water tap seems to release it, so that the heating then fires up.

Thanks, again.

 

[bribhoy]

Symptoms DO sound like a sticky DHW microswitch (most likely)/stuck diverter pin...get your Corgi man back and if you can get it to fault leave it in that position until he gets there...don't turn tap on/off. He should then be able to diagnose it very quickly

 

[Agile]

If he was unable to identify such a simple and on this model common fault then I doubt he has any ability to diagnose anything at all !

Tony

 

[richandjo]

If he was unable to identify such a simple and on this model common fault then I doubt he has any ability to diagnose anything at all !

Tony

Thanks for the reply, Tony.

So, in your opinion, it's definitely a sticky DHW microswitch or a stuck diverter pin - or does one come with the other?

Comment noted about our Corgi man if it was a simple and common fault to diagnose!

Is this problem simple to rectify with a few new parts or is a big job, involving a re-mortgage for parts and labour? If the latter, bring on a new condenser boiler, methinks.

Your help is appreciated, chaps.

Cheers...

 

[Agile]

""" So, in your opinion, it's definitely a sticky DHW microswitch or a stuck diverter pin - or does one come with the other? """

Without being on site I cannot say that anything is definate as I can only reply on what a non-engineer has said in non technical words.

All I can say is that whats been said points towards a diverter valve problem, either the valve or the switch or both and they are common faults on your model!

This is such a simple fault that even my Polish plumber would probably immediately see it.

Tony

 

[Softus]

This is such a simple fault that even my Polish plumber would probably immediately see it.

Perhaps I've missed some history here, but if that's the case then many other people will have too, so let's get something straight:

Are you saying that "your" Polish plumber is not very competent (a) because of who he is, in which case his nationality is irrelevant, or (b) because he's Polish, which is a racist view, or (c) because you're a prat?

 

[Agile]

He is a Polish plumber and does what most of them do, fitting bathrooms, heating systems and boilers!

He is not experienced at repairing boilers because he is a plumber, not a boiler engineer. He even knows how to do a gas tightness test!

Perhaps later I will teach him how to diagnose boiler faults but for the moment he will only be doing diverter valves and blocked plate heat exchangers.

Tony

 

[Softus]

So, the fact that he's Polish is irrelevant, and the fact that you used the phrase "even my Polish plumber" makes it a disparaging statement that is insulting to Polish people.

Perhaps later I will teach him how to diagnose boiler faults...

Perhaps later he'll teach you humility. And a modicum of fashion sense.

 

[richandjo]

Just a quick update:

Problem hopefully solved.

It was, indeed, a stuck diverter pin that, now that it has been freed, cleaned and greased, appears to be working properly.

Microswitch not faulty. No parts needed.

Many thanks to all who contributed.

Cheers...

Richard