On Sun, 17 Jul 2005 07:18:11 +0000 (UTC), "Hzatph"
wrote:

Interesting responses thank you. Giving Aga a call sounds a great idea and I
will do that. The pumped system will need to be turned right down so as not
to exceed the modest heat output capability of the Aga which is oil by the
way. I don't really want to run a 240,000 BTU boiler just to heat a water
cylinder in summer.

This probably wouldn't be too bad if a fast recovery cylinder is used.
These are able to take around 30kW of heat from a boiler, and this is
a 57kW boiler, so the cycling would not be too bad.


The boiler will feed something like 28 radiators so the
prospect of all being shut down sounds unlikely - a no-flow switch closing
down the boiler sounds much more sensible than a room thermostat in one
room.


I am not sure that this would work very well. TRVs tend to reduce
flow rather than cutting off completely unless the radiators are
oversized for the conditions. In effect, this would result in flow
continuing and the boiler cycling. By monitoring the temperature in
the room, the cycling period of the boiler will be much longer because
the room will cool slightly before the room thermostat signals heat
needed again.

It's difficult to say without trying it though. You could start with
the flow switch idea, putting a valve in line with the switch and
another bypassing this valve and the switch so that you can adjust the
flow rate through the switch and hence the sensitivity of the whole
thing.

If it doesn't work and a room stat is needed, you could use a wireless
one if you are bothered about the wiring. Initially this could be
just placed in the room that you think should be the monitored one and
the TRV full opened to disable its operation.



--

..andy

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