When running the hot water it goes cold after a couple of minutes for a few seconds and then returns to normal, this happens every 4-5 minutes.

Geoff Brookes, March 2009

Hi Geoff,

It could be that the diverter is not closing off the ch circuit and the water is not circulating around the secondary heat exchanger correctly, therefore causing the boiler to heat up rapidly and then cut off again. Another thing is to check that the water pressure is correct 1-1.5 bar, it may also be that the boiler is scalled up.

gary, March 2009