DHW problem on a BIASI boiler

[clangers_snout]

I have a BIASI M90E.32S combi boiler which is failing to regulate the DHW temperature. I know there are many possible causes for this, but when I was looking at the service manual it struck me that there is no flow regulator on the cold supply. If this is the case how can the boiler, which is of the gas modulating type, ever hope to maintain a constant DHW temperature?

At the moment I have to adjust the flow from whichever hot water tap I am using to adjust the water temperature, i.e. low flow for hot and higher flow for warm. Any ideas?

[John Rumm]

Sorry to dissapoint, but that is exactly the way the vast majority of combi boilers work. More of a problem in the winter and/or with low power combis.

One "sort of" workaround is partially shut off the stop valve on the cold mains feed to the boiler. That way you can limit the minimum temperature at a tap by pre-restricting the maximum flow. It at least removes some of the judgement required at the tap!

[Richard Conway]

That reminds me of the crappy old boiler in a rented house I lived in a few years ago. There was no shower so we had to have baths and the water was only any way near hot when you let it trickle into the bath. Only problem was, if you turned it down too much the boiler's overheat stat would kick in and you'd have to treck down to the kitchen in your dressing gown to override it. Did get it changed eventually but a PITA all the same.