Glowworm Ultimate 50FF + 2x Danfoss HPA2 valves for CH and HW.
Pressurised system. No frost stat and wiring (S-plan – I think) has been OKd by two separate engineers.
At the end of the day, the pump is not switching off when boiler/CH/HW shut down.
After the 6-7 minute pump overrun, the levers on the HPA2 are in the closed position but the pump remains on for hours. This tends to happen more when the whole system is hot and has been running all day.
If I switch off the pump via mains power at bedtime, and switch it back on in the morning the pump comes on even though the boiler cabinet is cold and the controller (Honeywell ST699) is not calling for heat. The boiler fires up when I switch the CH on.
If I then let the boiler run for about 1 minute – or an hour, and then switch off the CH, the boiler shuts down, the pump overrun occurs and the pump stops as normal.
The boiler ia 20 years old, has had several HPA2s and 3 (4?) PCBs. It had a new stat and PCB two years ago and a new top fan a month ago.
Could my problem be a faulty micro-switch on the CH (or HW) motorized valve after a prolonged period of heating or – as has been suggested - a faulty relay on the PCB? (but there are no noises coming from the control box). Or something else?
Any advice would be much appreciated
Pressurised system. No frost stat and wiring (S-plan – I think) has been OKd by two separate engineers.
At the end of the day, the pump is not switching off when boiler/CH/HW shut down.
After the 6-7 minute pump overrun, the levers on the HPA2 are in the closed position but the pump remains on for hours. This tends to happen more when the whole system is hot and has been running all day.
If I switch off the pump via mains power at bedtime, and switch it back on in the morning the pump comes on even though the boiler cabinet is cold and the controller (Honeywell ST699) is not calling for heat. The boiler fires up when I switch the CH on.
If I then let the boiler run for about 1 minute – or an hour, and then switch off the CH, the boiler shuts down, the pump overrun occurs and the pump stops as normal.
The boiler ia 20 years old, has had several HPA2s and 3 (4?) PCBs. It had a new stat and PCB two years ago and a new top fan a month ago.
Could my problem be a faulty micro-switch on the CH (or HW) motorized valve after a prolonged period of heating or – as has been suggested - a faulty relay on the PCB? (but there are no noises coming from the control box). Or something else?
Any advice would be much appreciated