boiler keeps switching itself on then off

[huwy123]

hi there,

I've noticed a problem with my boiler in that approx every 10 mins it will switch itself on for 20 secs (and then off again). It does this even if the CH and HW are set to off on the programmer and the thermostat is turned right down.

I've an ideal classic SE15FF boiler with a drayton programmer. I haven't had it serviced for years which I now realise was incredibly stupid (never really though about it).

I'm not a plumber and I'm pretty sure I'm going to need to call someone out but I wondered if there's any basic troubleshooting I can do for this?

Cheers,
Huw

 

[Agile]

You may have a froststat which is activating.

Tony

 

[huwy123]

thanks for the super quick response.

I've read up on the frost stat and I think it's unlikely I've got one. I live in a 2004 townhouse with the boiler in the kitchen and the water tank on the top floor.

Cheers again,
H

 

[Ray84]

sounds like you have a faulty zone valve, i dont think its a repair you'd be able to carryout yourself

Ray

 

[Agile]

A zone valve would be unlikely to fault every ten minutes.

But anything is possible.

Easy enough for a professional in front of the boiler.

Tony

 

[namsag]

Yes it would .
A stuck microswitch on motorised valve will have pump and boiler running constantly with heat going around bypass as the valves would be closed .
SO boiler would be cycling on boiler stat and turning off and on at regular intervals.

80% Of the time a flick of an electricians screwdriver and a bit of wd40 will fix it
Otherwise its a change of valve head or complete valve dependent on make of valve

 

[huwy123]

thanks for the replies.

I will ring around today for a plumber.

Just so I'm clear is it the "Zone Valve Actuator" thats likely to be the cause?

I will upload pictures in case that helps!

Once again thanks for your help!

-Huw

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• huwy123
• 9 Feb 2011
• 1

Untitled

• huwy123
• 9 Feb 2011
• 1

Untitled

• huwy123
• 9 Feb 2011
• 1

 

[Agile]

Thats right, it could if the sytem has two port valves.

Huw, do you have two motor valves?

Does the boiler heat itself up but not the CH or HW?

Tony

 

[namsag]

Out of those two motorised valves its more likely the white drayton one has the sticking switch

 

[huwy123]

It looks like the boiler is only heating itself up. The rads don't feel warm and the HW is not that hot.

So could it be as simple as the plastic switch on one of those units is stuck - could I just apply some wd40 and move it?

Once again thankyou!

 

[Agile]

The white one has a black plastic manual lever.

I have found them to be very unreliable and the bits often break. It could be something as simple as that being broken or jammed.

Has anyone touched that lever?

Tony

 

[huwy123]

I can't imagine anyone has touched. I'll have a look when I get back from work.

Cheers again.
Huw

 

[huwy123]

Update - I have had a chance to look at this further. It looks like the drayton zone actuator is running constantly - even when the boiler is completely switched off. The pin is in position A. If I push the switch at the top over it just resets back to the on position.

I have a proper plumber coming around tomorrow to look at it.

-H

 

[huwy123]

Just to update eveyone I replaced the valve mentioned above and it has been working perfectly since (touch wood). Thanks a lot.
-Huw