On 15/05/2021 17:32, John Rumm wrote:
On 15/05/2021 16:54, ARW wrote:
On 15/05/2021 15:57, John Rumm wrote:
On 15/05/2021 11:27, Theo wrote:
John Rumm wrote:
It was quite common to have aÂ* big cast iron lump HX with high water
content (couple of gallons). That would have 4 bosses on it - two
outputs and two returns. One set would be used for the feed and return
on the pumped circuit through the rads, and the other two would be
used
for a gravity (i.e. convected circuit) to heat an indirect cylinder.

Ah, so 'gravity' meant there was no pump on the HW side, only for
the heating?

Yup, DHW looked after itself, and the pump only served the rads.


The upstairs rads (or some of them) would have warmed up (not to full
heat) if it was not for the anti gravity valve on the heating flow side.

Sometimes part of that was intentional, they might put the bathroom rad
in the gravity loop for the cylinder rather than as part of the heating
circuit.



I had forgotten about that one.

A few years ago I did a combi as an S plan and the bathroom rad was one
of the zones. The flow sensor on the bath hot tap triggered a timer to
operate the bathroom 2 port valve

--
Adam