On Mon, 13 Mar 2006 20:45:14 +0000, Adrian Brentnall wrote:

Only trouble there is that you'll quickly get to the point where your
DHW is 'hot enough' - and then what are you going to do with the
'surplus' heat....?

Agreed, even a small wood burner is quite capable of boiling a cylinder
of water in a few hours.

Would a heat dump radiator be required or advised?

It's somewhere for the 'spare heat' to go - after you've got the DHW
tank as hot as you want it....

Aye, one thing you don't want is you boiler boiling, you must be able to
get rid of the heat and it must be fail safe. ie the heat must still be
capable of being dissipated when mains power has failed and backup power
systems have run flat or out of fuel. When the power goes is when you
really need the wood burner to be on to provide heat for the house.
Having to shut it down to stop it exploding strikes me as just plain
silly.

IMHO the only way to reliably achieve this fail safe mode is with a
gravity loop.

If you do that you'll maybe find it difficult to 'turn off' the
circuit....?

Should I have a separate header tank or could the existing one for the
oil fired system be used?

You might want to work on the two systems independantly...?

Isolation valves that can be locked open on the wood burners gravity loop
would enable the different primary loops to be isoloated for maintenance
if required.

A Dunsley Naturaliser is the way to go but from my investigations of the
device it is nothing more than a sealed empty box where all the loop
feeds and returns (oil boiler, wood burner, cylinder and CH) come
together.

--
Cheers
Dave. pam is missing e-mail