We may be getting somewhere.

On Monday the diagnostics showed that the PHE return temperature sensor was in error. Parts Center stock these, and I got a replacement for £20.

Yesterday two different plumbers came around to attempt to fit the part. The first couldn’t figure out how to isolate the sensor from the water pressure, so couldn’t carry out the switch over. The second took one look at the system and said he wasn’t qualified to touch it!

Today, a third plumber came out and phoned Gledhill for advice. The procedure was very straight forward (isolate the PHE pump using the valves, turn off the mains water, and drain the small header tank using the drain point next to the sensor).

We now have working hot water – but the sensor is still reading an error! The next step is to replace the main board, which I will only do if the problems resume again.

I have just found out that our next door neighbour is having exactly the same problems.