Logic Combi ESP1 35 always showing demand for Central heating

[John.g]

That's great news.

During all the time your boiler was running on/off with the zone valves closed how did the boiler have minimum circulation?
Is there a ABV installed and if so is/was it noisy in operation, if installed, what make.

 

[theboyroberts]

Abv?

I don’t think there is one.

 

[John.g]

Your boiler may have its own internal by pass which must be pretty good otherwise all that running with no flow wouldn't have done the Hx any good or maybe its stainless.