In message , andrew
writes
Tim Lamb wrote:

Ah! I had not considered you as a Hetas adviser.

I'm not, the commercial stuff I did didn't need part J. Unfortunately the
firm I was doing that for went bust when the Austrian boiler manufactures
decided to market to GB directly, order book suddenly vanished. The staff
and directors seem all to have been paid off, it was only creditors that
were caught, that included my last months bill ;-(.

Let us hope their pension investments are in something Icelandic.

Angela is badgering me
to install a wood burner to back up the central heating. I have got as
far as discovering that anything over 4.9kW requires an air supply and
that you can mix gravity water with pumped CH water with a neutraliser
but my cheque book hasn't twitched yet:-)

It's only a 6" air brick! Actually 5kW is fine for a back up.

Yes. Actually there is a suspended floor so I am considering installing
a duct terminating next to the hearth. Logistically, any log burner will
only operate while there is somebody to light and feed so early morning
heat will always be gas.

Lining the existing chimney looks straight forward as does adapting the
register plate. Where I am struggling is whether to go for room heat
only , graft a 2-3kW gravity back boiler into the existing gas system or
go for something with a wrap around boiler producing 10kW or so but,
presumably, needing much more complication by way of controls.

In fact for
mild days you'll have noticed that a cheap reversible air conditioner is
cheaper than gas or oil because the delta T it pumps through is low and the
COP is high.

I have ground/water source heat pump in mind for a different project.
Air-con is something I have never considered for a domestic use.

The neutraliser is just a ridiculously small, expensive thermal store, I'll
bet you can do it cheaper with a hot water cyclinder and some zone valves.

2-300ukp from Dunsley. I assume there is a limit to how much heat you
can transfer using gravity and a fixed bore/head system. I must ask
them. They don't seem to answer e-mail:-(

cross posted to uk.d-i-y

regards



--
Tim Lamb