On Tue, 28 Sep 2004 10:11:07 +0100, "Set Square"
wrote:
In an earlier contribution to this discussion,
Andy Pandy wrote:
As a test I just checked rad in bathroom which was cold. I the turned
hot tap on for 2 mins to start boiler and pump (ch off, hw continuous
on programmer and room thermostat in living room off, all other rads
cold)
and the pipe going into rad got piping hot though the rad will just
get warm and stay that way.
could the mid valve be open a touch ? enough to push a touch of hot
water to this rad but not enough to get it piping hot or spread to
other rads??
It's more likely that you've got reverse circulation - or single pipe
circulation up the return pipe. When this happens, how hot is the CH outlet
pipe from the 3-port valve? [I would expect it to be warm for a foot or so,
purely by conduction - but to be cold beyond that unless the valve *does*
have an internal leak.
If you want to investigate further, you may need to take up one or two
floorboards to see exactly where the pipes go!
What I would expect is the following:
Flow pipe (22 or 28mm) coming from boiler. Connections for expansion and
fill pipes, then the pump, then the inlet to the 3-port valve.
One outlet from the 3-port valve (22mm) goes to the top of the heating coil
in the hot water cylinder.
The other 22mm outlet feeds the radiators, with individual radiator feed
pipes tee'd off it. [It may also split into 2 or more branches, depending on
the layout of your house]
The returns from the radiators should also all be combined into a single
(probably 22mm) pipe which, in turn, joins with the return from the coil in
the hot water cylinder before returning to the boiler. There may be a
'balancing' gate valve in the return from the hot water coil before it
combines with the CH return.
What you should *not* have, is any radiator returns connected into the
boiler return pipe *after* the point where the HW return joins it.
Hope this makes sense!
Will print and digest. just wanna let ya know that i have the info
thanks. Will reply soon.
Andy
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