"Set Square" wrote in
:


Thanks for the link. Looks interesting! May not be too easy for
diy-ers to diagnose if the integrated logic goes wrong.

As far as I can see, you still have two water circuits with a common
feed from the boiler. I can't see any reason why either pump should
induce any flow in the other circuit. However, there is nothing to
stop gravity circulation if either circuit decides to do its own
thing.

But one pump is fed not only from the boiler but from the other circuit,
unless there's something to prevent backward flow, as the are common at the
input of both pumps, and at the boiler return which would be at a higher
pressure.

I admit I don't know for sure, but having sketched it out, I'm more
convinced;

The gravity bit is the other thing; in the absence of any forced flow,
would the hot water cylinder cause a flow through the rads and cool itself
down?

Of course the maker prolly knows what he's up to - I just wish I knew more
before taking the plunge

mike