I need something that will break on temp fall, which is why I am stumped. Unless I am being really dumb and missing something.
How would you intend to detect the water's getting hot without any flow in the pipe? Or would you turn the pump on manually?
There seems to be a solution in the form of a flue thermostat:
http://www.stovesonline.co.uk/wood_burning_stoves/Flue-thermostats.html[/QUOTE]
A flue stat is normally used with a loading unit where the sf boiler is heating a large thermal store or accumulator.
The load unit then takes care of the return temperature and some (like the Laddomat) also allow gravity circulation in case off a power failure.
The flue stat on its own cannot prevent cold water entering the boiler casing and lowering the efficiency.
Just the same as a pipe stat on the flow will not either.
The earlier link posted with the Woodwarm instructions is how it should be done.
Should be no pumps or valves on the primary return to a stove.