Thermal stores - what sort of timer/thermostat arrangement for the radiators?

Boiler connected to the thermal store. Thermal store connected to the rads.
Thermal store on thermostat and timer - so cylinder calling for heat is the only control over the boiler (timer will probably be set to either continuous, or off for holidays, or possibly a nightime quiet patch). (and boiler controls pump and pump overrun)
But what control of the rads?
There will be two radiator circuits (open plan main area kitchen & cloakroom wc, and bedrooms & bathrooms), and operated on "pump plan" with a further pump on each circuit.
The building layout is unusual with no obvious place for room thermostats, so I'm considering all rads fitted with TRV's, and the timer for each circuit just controls the pump for that circuit (with automatic bypass valves if all trv's are closed on that circuit).
This would mean the pump runs continuously during a heating "on" period, but power consumption of a pump seems to be about a lightbulb's worth.
From a user perspective, you have the hot water timer that needs to be on whenever you want water or heating (and is best left on all the time), two timers for each of the rad circuits, and no thermostats - just trv's. I've seen a nice 4-channel timer that wraps the functionality up into one neat little package.
(Other details that probably don't affect the overall picture - the main open plan area is on two levels and also has a woodburner (so main area trv's might be set to "off"), boiler is non-condensing oil- fired.)
Advice, suggestions, feedback?
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wibbled on Wednesday 28 October 2009 21:17

A modulating pump will help for starters. That will attempt to maintain a certain pressure rather than just thrash its guts out. Might need a bypass valve? Wait for a comment from one of the more experience people here.
Another solution is to use the Honeywell CM-Zone electronic radio TRVs. These need a radio programmer, which, IIRC can manage 2 zones. But I *think* the temperature on at least one zone, possibly both as an option is measured at the rad valve.
The whole lot can then be bound to a radio relay (eg HC60) that switched your pump on. then you get a call for heat (pump) only when something really wants it. And lots of zones with different times and temp profiles.
Again, IIRC, the HC60 can be bound to upto 8 zones, but you'd need to check.
It's not cheap, but it's not silly money considering you don't have much wiring (because it's all radio based).
You can buy the stuff here:
http://shop.smuk.at /
(because Honeywell UK are dickheads who think we users cannot be trusted to set up something like this). Some bits are available in the UK, but the Austrian guys have more interesting bits at better prices.
--
Tim Watts

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bear in mind trv's are only partially thermostatic, a single setting cant maintain a consistent room temp.
NT
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