In article , wrote:
How would I go about finding the return? There is no access to
any of the pipework except in the airing closet where the hot
comes in. Presumably where the coil exits the hot water cylinder
is a return - would that join the CH return and would it
therefore do to connect the loft radiator return to the hot
water return?

If you do you might just have problems with radiators getting warm when they
shouldn't: if returns from the heating connect into the system at two
different points (A and B in the diagram below), when the DHW is on the
pressure at these points will be different so you may get a reverse flow
through the radiators.


reverse circulation
------+-------------+---------- CH flow (off)- || --+
RAD RAD |
reverse^circulation V |
| | Pump |
+---A-------------B------------------Boiler --X----MV
| |
CYL |
| |
+----------------------------------O---HW flow ----+

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Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
Free SEDBUK boiler database browser http://www.sda.co.uk/qsedbuk.htm