Boiler Fires Up On It's Own ??

[Dectomax]

Hello,

I have a Myson Apollo boiler on a gravity fed system. I've only recently noticed that about every 20 minutes or so, the boiler will fire up burner and all, for about 30 seconds and then shut down again. Not good with present energy prices!

I have turned the hot water and central heating on the timer unit off, the thermostat by the front door to zero and it still does it. I know the flu fan used to turn on and off periodically, I presume to vent any gasses from the pilot light but I can't remember the boiler turning itself on.

Is this normal and if not, any ideas??

Also, as this boiler is getting old (20 years), can anybody suggest a good replacement boiler should I eventually invest in having a new one installed.

Thanks.

 

[Agile]

It sounds as if there is a call for heat and the boiler is just keeping itself warm.

Its likely to have a fault in the control circuit providing a call for heat.

There are lots of suitable condensing boilers.

Tony

 

[Dectomax]

I see,

I initially thought that there may have been a faulty frost stat or something keeping the boiler ticking over but I don't think my boiler has one, according to info an the BAXI technical info site.

If it's the main timer unit calling for heat then that's odd because I can switch it off and this still happens.

Would anything else on the circuit call for heat with H\W and C\H switched off?

Thanx

 

[namsag]

Ignore Agile he can be a pr#ck at times . The most likely fault will be a microswith stuck inside one of your motorised valves which then allows power to pump and boiler causing it to cycle

 

[D_Hailsham]

If it's the main timer unit calling for heat then that's odd because I can switch it off and this still happens.

Would anything else on the circuit call for heat with H\W and C\H switched off?

This boiler has a permanent 230V supply to run the pump overrun feature, so just because you have the CH and HW turned off at the timer does not mean that there is no voltage at the boiler. There should be a fused switch which will turn everything off.

Doe the problem occur with the boiler temperature switch in both H and L positions? Does the boiler go off with the switch in the 0 position?

 

[Dectomax]

Ignore Agile he can be a pr#ck at times . The most likely fault will be a microswith stuck inside one of your motorised valves which then allows power to pump and boiler causing it to cycle

Ahhh, would this include the mid position motorised valve?? I've suspected this is faulty for a while because the upstairs rads get warm when I have only the hot water on.

@ D_Hailsham

Yeah, If I kill the main power switch, the whole boiler, timer etc shut down. This only happens when the timer is awake ie, clock working etc but the C\H and H\W are in the 'OFF' setting. Also if I set the stat on the boiler to the '0' position it stops.

 

[namsag]

By it not doing it with stat in O position that rules out the gas valve passing also .For gas valve to be firing it means you are getting power down the switched live which comes through the 3 port mororised valve and as you are also getting warm rads when just HW on it would suggest valve your most likely culprit

 

[Dectomax]

Okidoke. Thanks everybody. Looks like I'll be changing that valve at the weekend.

 

[D_Hailsham]

For gas valve to be firing it means you are getting power down the switched live which comes through the 3 port mororised valve and as you are also getting warm rads when just HW on it would suggest valve your most likely culprit

But the OP said:

This only happens when the timer is awake ie, clock working etc but the C\H and H\W are in the 'OFF' setting.

If the CH and HW are both OFF at the timer there should not be any power reaching the motorized valve. So either the timer is faulty or the boiler is being powered from somewhere else.

To the OP
The problem stops with the boiler stat at 0, but what about the H and L positions? Does it happen in both?

There may be a problem with your valve letting by (warm rads in summer), but that is not the cause of this problem.

You say that you have turned the CH room stat right down and it still happens. What about the cylinder stat, is this right down as well?

 

[Agile]

Ignore Agile he can be a pr#ck at times . The most likely fault will be a microswith stuck inside one of your motorised valves which then allows power to pump and boiler causing it to cycle

It is pity that people who work for British Gas seem to learn to be abusive to their customers and in particular to other boiler engineers.

Initially that seems to reflect badly on BG but in reality it may be because they feel somehow technically inferior and think that attacking others boosts their standing. Realistically it justs reflects badly on themselves!

I also wondered if it was a stuck valve microswitch but depending on how the system is wired then the supply might be removed when there was no output selected on the programmer. Therefore I blandly limited my comment to a control system fault.

To identify the fault in more detail it will be necessary to perform some electrical tests, simple to us but not necessarily something you are equipped to do or even that we could expect that you can do safely.

Tony

 

[namsag]

D hailsham are you forgetting about the live that is given to the 3 port valve on the grey wire from the CH off terminal in the clock . There maybe a fault within the valve allowing power to carry on to the boiler when it shouldn`t

Agile
1st . If you think good advice is to say there are lots of suitable condensing boilers then i stick by my original comment

2nd I don`t work for BG and you are not my customer and neither do you have any official papers that call you a boiler engineer . The day i will ever come close to feeling technically inferior to some one like you, i will ask the doctor to test me for alzheimers.
My diagnosis may not be correct put it will put him more in the general direction of where the fault lies than what you appear to do ie getting your post count up without actually helping

 

[D_Hailsham]

D hailsham are you forgetting about the live that is given to the 3 port valve on the grey wire from the CH off terminal in the clock . There maybe a fault within the valve allowing power to carry on to the boiler when it shouldn't

I think you the HW off terminal; but, yes, I had forgotten about that wire.

According to Honeywell leaflet How a Mid position Valve Works, if there is 240V on the grey wire only, the valve is held at its last port of call. The solution is either to turn the HW ON at the timer or turn the power of completely. The valve is then reset by the spring to port B open.

Might be worth a try.

 

[namsag]

Yep i meant the HW off terminal.

 

[nickso]

It is pity that people who work for British Gas seem to learn to be abusive to their customers and in particular to other boiler engineers.

Initially that seems to reflect badly on BG but in reality it may be because they feel somehow technically inferior and think that attacking others boosts their standing. Realistically it justs reflects badly on themselves!

its pity agile has a short memory about his own particular brand of abuse to customers, this is after all the man who said he wont visit customers who dont give him a cup of tea on his first visit, superb customer service.

a BG engineer who is abusive to customers will last all of three days i'd imagine.

any regular poster feeling technically inferior to you is not a likely scenario.

 

[Agile]

its pity agile has a short memory about his own particular brand of abuse to customers, this is after all the man who said he wont visit customers who dont give him a cup of tea on his first visit, superb customer service.
.

Interesting that you twist round what I said.

All I said was that I dont go to future visits quite as quickly if I remember that a customer did not give me the courtesy of offering a cup of coffee on a previous visit.

A few of my customers have stopped using BG because they have found the engineers unhelpful and in one or two cases abusive and threatening. They did not find making a complaint helpful.

Tony