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Hello
I'm seeking helpwith a central heating problem please. It's a fully pumped system with a diverter valve for cylinder / rads and has an open header tank. Potterton Prima 40B.
The first sign of trouble was yesterday evening, no hot water. The hot water and radiators had been ok earlier in the day.
The pilot light was out so I easily re-lit it and turned the control valve back from the igniter setting to on. The main burner fired, job done I though, but it wasn't.
No hot water this morning.
The pilot lights easily and stays on if there is no demand for heating. The pilot flame looks like it's bathing the thermocouple. Once a demand is placed, the main burner fires immediately, then 10 to 60 seconds later there is a click and both the main burner and pilot are extinguished. This is repeatable. I can't see if the pilot flame is bathing the thermocouple correctly once the main burner fires, there is just too much light in there. I checked the thermocouple with an Avometer. Minimum scale is 3V so only millimetres needle movement however the reading is consistent with 20 mV. My DVM isn't at home and it'll take a couple of hours to get it. The pump is vibrating, so seems to be working.
I followed the fault finding chart in the instructions and it doesn't really cover this situation.
Anybody have any thoughts please?
I'm seeking helpwith a central heating problem please. It's a fully pumped system with a diverter valve for cylinder / rads and has an open header tank. Potterton Prima 40B.
The first sign of trouble was yesterday evening, no hot water. The hot water and radiators had been ok earlier in the day.
The pilot light was out so I easily re-lit it and turned the control valve back from the igniter setting to on. The main burner fired, job done I though, but it wasn't.
No hot water this morning.
The pilot lights easily and stays on if there is no demand for heating. The pilot flame looks like it's bathing the thermocouple. Once a demand is placed, the main burner fires immediately, then 10 to 60 seconds later there is a click and both the main burner and pilot are extinguished. This is repeatable. I can't see if the pilot flame is bathing the thermocouple correctly once the main burner fires, there is just too much light in there. I checked the thermocouple with an Avometer. Minimum scale is 3V so only millimetres needle movement however the reading is consistent with 20 mV. My DVM isn't at home and it'll take a couple of hours to get it. The pump is vibrating, so seems to be working.
I followed the fault finding chart in the instructions and it doesn't really cover this situation.
Anybody have any thoughts please?