"Alan" wrote in message
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It is often simpler to add a pump to the former gravity circuit and
leave the central heating pump where it was. These pumps can then be
controlled by a thermostat and time clock as appropriate.

OK, this may be an option. The S-Plan+ suggested by Roger is another
solution.

The only major thing to watch is that the gravity circuit was often
used as an expansion pipe and this must not be interfered with.

You're right, it is. I'll have to design this into the new system.


Last autumn I converted my house. It is 2 storeys and has a solid ground
floor. The C/H distribution is between the two floors. Installing separate
distribution for each floor would have been very difficult, so I just have
one zone. The system is controlled by the same programmable thermostat
(Danfoss TP9). The sensor is in the sitting room. I find that I can
achieve a sensible heat distribution throught the house by a one time
setting of the radiator valves.

My pump is on the return just before the boiler where it always was. The new
valves are just before that.

The expansion is unimpeeded via the old gravity H/W flow pipe.

I installed a new feed from the header tank which connects between the pump
and boiler - so there should always be water in the boiler.

(The original feed was via the old gravity H/W return pipe. )


--
Michael Chare