Worcester Bosch combi - cutting out on water

[Iliketulips]

Our boiler is cutting out after our hot water has run for approx 80 seconds, but only when heating has been running, ie both work independently of eachother and we can run hot water as long as we want if heating hasn't been on.

I watched it this morning - ignition cut out after approx 80 seconds, tried to re-ignite (unsuccessfully) and then just kept running inside (longer than usual) even though DH had turned water off. Twice we've had to reset it, the others the heating has actually switched off after even though would normally start running.

Waiting for engineer to get back to us. Any ideas?

Just trying to gauge roughly how much a repair could be, as the mechanical timer loses track of time quite a bit (although the latter won't be too expensive).

Could be a few things.

Could be that it is overheating. Maybe because of reduced flow or maybe because of a faulty temperature sensor.

What fault code does it give on the display ? You should be able to search on that.

Maybe if you drop the heating circuit temperature or the hot water temperature it will be OK, as it won't get hot enough to trip.

Our boiler is a Worcester Bosch 28i Junior. I guess it's a basic model as does't have a digital display, so no fault codes. Can't adjust the hot water temperature on boiler, and if we were to turn down the temperature on shower, it wouldn't be warm enough.

Will reduce heating temperature on boiler, although it's set to 4 which I understand is more efficient for this type of boiler.

My guess it could be one of many things. Partially blocked heat exchanger on the dhw circuit, the pump could be on its way out. It could be a problem with either the temperature sensors or maybe less likely the flow sensors. Pressure in the heating circuit could be an issue but normally is lower when cold than when it heats up.

I think you just have to get the engineer in and see what they say in the absence of any diagnostic information. Moving parts are nearly always the first thing to break. So valves, fans, pumps. Heat exchanges can get blocked up or corroded.

I guess as a boiler it is getting on a bit although maybe not that old for a WB.

Mine did that, engineers came fixed it for a bit then it started playing up again. I got fed up especially as each engineer gave a different reason, I ended up getting a new boiler and wish I did that sooner, (however the boiler was over 20 yrs old and was fine for 17 years)

Thanks everyone. He's coming out this morning. He explained that it's usual for the boiler to try and kick in four times, that's why it re-ignited - obviously failed the other three times. He's eliminated a couple of things from what I've said, but obviously needs to assess while here.