Glowworm Ultimate No Hot Water

Went to have a look at a Glowworm Ultimate as the customer was complaining that the pilot light had gone out, and there was no hot water. The boiler was a fan-flued model and so did not have a permanent pilot. The overheat thermostat had not operated on the control panel either, 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 three-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 or the hot water connection from the programmer, but there was power on the grey wire. Disconnecting the wires that were connected into the same terminal as the grey, the power was coming from the hot water off of the programmer even though the hot water was set to be on at the programmer.

The existing Danfoss FP975 programmer was on a standard backplate, so replacing this with a Drayton LP241 was straightforward. I would have preferred to fit another Danfoss programmer, but only had the Drayton in my van stock which is a perfectly good programmer. Replacing the programmer solved the problem and the hot water and heating are both working correctly again.

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.