Why oh why does my boiler stop firing...

[JJBlinks]

At the same time each day?

It randomly turns itself off, stops firing, the house is freezing and then over a house later comes back on...?!!!!

An “hour” later...

Is your pressure too high?

perhaps it is getting too hot and the overheat stat cuts in.

How old is it?

When was it last serviced?

Have you got a hot-water cylinder?

How hot is the tapwater?

Show us pics of your timer/programmer and wall thermostat please. And of the boiler and cylinder, if any.

These are the pics. I suspect it’s fairly old - we bought house last year. We have it serviced. The water is v hot. We have a hot water tank.

Can’t access the cylinder....

There isn’t a room thermostat....

I see you have the programmer set to 24hr "on" for HW and CH, which is rather uneconomical.

You ought to get a room thermostat fitted, again, it is uneconomical without one.

It's possible that there is a fault causing your HW to be too hot. Set the HW to "off" tomorrow, and see if it continues to get very hot, or if it goes cold.

Depending on your system and the colour of your cylinder, it will probably take about an hour to heat up if it goes cold.

I can't see what temperature your boiler is set to. Is it at max?

Are your radiators too hot to hold all over?

Why is your cylinder inaccessible? In the loft, or in someone's bedroom?

Can you get into the loft and see if either of the water tanks is warm (or hot, which is much worse)? Work out which room is beneath the tanks, please. Is there any sign of water coming out of the overflow pipes outside the house?

btw, although your programmer is badged British Gas, it is actually a Drayton, probably a 722 or 522.

Guidance on setting it is here...

If you fold down the flap it might be possible to identify it by the shape of the buttons, and the number of days you can set.

Thanks for all of this PigletJohn - it’s normally set on a timer but when it plays up I pop it onto “on” for both hot water and heating to make sure they are both on and there is hot water for evening bath for children.

The water coming out of the taps is scalding it’s so hot. But the raidiators don’t get too hot to touch - they are warm but not roasting. I was advised by BGas to put the boiler temp on maximum to keep the raidiators hot enough.

The boiler is set into a space above the room where the timer is - is a 4 bed detached 1930s House. I’ll need to see if I can remove the wood and investigate. It’s on the ground floor level of the house.

No sign of any water flow outside the house.

I’ll try turning the hot water off today and see what affect that has.

Thanks so much for all your help!

The hot water cylinder might have an immersion heater controlled by an electric switch. Please make sure this is turned off. It is only needed if the boiler breaks down. Scaldingly hot water is dangerous, especially if either of the water tanks in the loft (probably square) are warm or hot. If you have a thermometer, please test the hot tapwater.

If you can photograph the pipes, pump and valves around the hot water cylinder, this is probably where the fault lies.

Sorry for not coming back - my middle DS is not well. The tank is yellow and is v hot...

So BGas advised me to have my hot water set to “once” as I have small DC and so need hot water all the time. I think that this may be the issue. So I turned the water off today and just set the water to come on at 6 for an hour before bath. The boiler did not cut out tonight so will do the same tomorrow.

Am thinking you are right about the water getting so hot is going into override.....

Will try the same tactic tomorrow and report back. Thanks for all your help so far - it’s been a huge help...

if you turn the HW "off" and it still gets hot, I know the most likely problem. If it doesn't, I know another cause.

photos round the cylinder will help.

If it was all working correctly, the "HW = Once" from about 7am to 10pm (to include all your showers and baths) would be OK, though mornings and evenings (still including all showers and baths) would be a bit more economical.