Another Glowworm Ultimate With No Hot Water

Went to have a look at another Glowworm Ultimate as the customer was complaining that there was no hot water. The overheat thermostat had not operated on the control panel, and there was no orange glow from any LEDs on the PCB.

I looked at the programmer, heating and hot water were both set to be on, and the red lights illuminated for both. I went to the airing cupboard and the system was a two-port set up. Removing the cover to the electrics in the airing cupboard I checked out the voltages at various terminals. There was no power at the orange, but there was power on the grey wires. There was power on the supply to the cylinder thermostat and brown wire to the hot water two-port, but the valve was not opening. I also checked that there was no power across the neutral and the earth.

Manually opening the valve caused the pump to start running so I knew that the microswitch was ok, but the motor in the valve was not operating. I drained the system and replaced the two-port zone valve on the hot water side. Testing the valve after it's replacement and the hot water was heating successfully.

Disclaimer: The works described in this blog are a record of work undertaken and should not be taken as guaranteed to solve your problem. Work should only be carried out by persons qualified and competent to do so.