In April we noticed that the CH pump continued to run on and on after the timer went off, not for just the usual few minutes but all through the next day. Also it seemed the boiler would fire for a minute or two despite no demand for hot water from taps or the room stat. For no reason it righted itself the next day. But now the problem has returned and the pump has been running for 2 days non stop. Only previous issue with the pump (a Grundf UPS 15-50) not starting once when the CH went to ON, and I seemed to clear that by switching it from 1 to 3 and back again which somehow woke it up and we've had no repeat since. Given the evidence are we looking at a new PCB?
Pump won't stop running Glow-worm Ultimate 50FF
- Thread starter Kentucky
- Start date
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Faulty 2 or 3 port valve
You have a fault on one of your motorised valves. Probably the end switch sticking on one of them. I'm assuming that you have two valves, and that the hot water valve is the culprit. Only by testing will you find the fault. If you are not ok with electrical testing then a good repairman will find that fault in 15 mins. The make and model of your valves will determine how the repair is done.
Deffo not the PCB
Deffo not the PCB
Thanks for those replies. Reason I suggested PCB was that the 50FF instruction book flow charts for fault finding on pump overrun has 'does the pump continue to run after SL is interrupted. If YES does the pump stop after several minutes. If No - Faulty PCB replace. Another thing I've noticed having slid out the bottom part of the boiler cover is that one amber light is lit even though timer is all OFF. They would normally all be dark. Is that in line with your advice? There are two motorised valves both Danfoss HPA2, one close to the pipe coming out of the middle of the ariston tank and the other lower down near the pump. Have experienced motorised valve seizing up at my old house after it got flooded when a pump was installed above it. The two on this system both have the metal arm at the Auto position. Is it worth having a go moving one or both of these to Man to see if that may result in a short term fix? Thanks
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The fact that the boiler fires is a sure sign of a motorised valve fault.
Remove the actuators(2 screws) and check the valve spindle moves freely allowing the valve to return to closed under spring return.
You will have a wiring centre that the valves are connected to and you need to check which one is supplying (via the orange wire) power to the boiler when programmer is set to off period.
Identify that wire and then you have found which valve is faulty.
Replace the power head and wire like for like in the wiring centre.
Remove the actuators(2 screws) and check the valve spindle moves freely allowing the valve to return to closed under spring return.
You will have a wiring centre that the valves are connected to and you need to check which one is supplying (via the orange wire) power to the boiler when programmer is set to off period.
Identify that wire and then you have found which valve is faulty.
Replace the power head and wire like for like in the wiring centre.
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