What flow rate does DHW turn on? My boiler works fine for CH but I have noticed recently that DHW has been problematic. The HW sometimes does not turn on until the tap is turned fully on and when I back off the flow rate to get hotter water, it turns off again. Usually I can get it so that is just over hand hot and occasionally it does get hotter than usual at much reduced flow rate. Today I could not get HW in the bathroom and I left the tap running full on and checked the boiler and it was not calling for heat. I used a 2l jug and stopwatch and the max flowrate is about 5 l/m for the bathroom and the kitchen about 12 l/m. I am guessing that it is something wrong with the diverter valve microswitch but wanted to check.
I do have a service contract for the boiler but I wanted to check before I get told that I need a new boiler since the boiler is over 20 years old.
I do have a service contract for the boiler but I wanted to check before I get told that I need a new boiler since the boiler is over 20 years old.