Tim Lamb wrote:
Heading into the home heating season, I am giving consideration to
installing a log burner. The existing fire opening and flue are
adequately sized for something up to 12kW and I think a flexible liner
should be easy to install. There is enough dead standing timber on the
farm to see me out, so security of supply is not a major issue.

However, although this is an open plan house including open stair well,
the most convenient location is in a room only 14' x 14'. I guess
anything over 6kW in such a small space will seriously overcook us.


Open the doors Tim. It will at the least heat the room above, and some
adjacent ones, leading to a general reduction in CGH bills, and a
woodburner can be throttled way back, especially with good dried wood as
fuel.


Conversely, the ability to draw off useful hot water seems limited to 1
or 2 kW at most.

That is enough to fully heat a large insulated house for 3/4 of the year.

At the risk of awakening Drivel, how would one incorporate such an
intermittent source of heat into a gas fired fully pumped system? The
existing hot water cylinder, pump and controls are conveniently directly
above the preferred location: assuming the joists are adequate!


You probably need some sort of secondary pump and seection of morosed
valves that will circulate that hot water thruogh all primaries instead
of te boiler. I.e. some form of changeover switch so that when there is
enough heat being produced by the fire, it takes over as a 'boiler'


An alternative approach would be to run the CH/DHW return through the
woodburner to 'preheat' the water ..that would work very well indeed,
except that when the burner is on, and there is no call for heat I can
foresee the ruddy thing boiling. ISTR the usual approach here is a
gravity fed towel rail or whatever in the woodburner circuit.


MM. I think the latter approach offers the best way..just need a way of
dumping heat out of the burner backboiler when no call for heat exists.
Maybe you could couple in some kind of thermostat to turn the pump on
and the CH on whenever the boiler reaches critical temps. And use the
house CH as a heat dump. Simply wire that lot in parallel with your
normal timer and main stat..

Interestingly, this approach means the stove itself when not lit becomes
a rather cute radiator..



regards