On Mon, 14 Jan 2013 09:29:12 -0000, David WE Roberts wrote:

You can get thermometers which clamp to the single wall flue above the
stove.

Or an infrared thermometer? That would have more uses. CPC have what
looks like quite a decent and cheap one on offer ATM. Dual laser,
adjustable emissivity (0.1 to 1.0), 12:1 distance:spot. £32.95 + VAT
IN0545703 normally £38.47 + VAT.

This lets you know if you have the flue gasses warm enough.

How warm is warm enough?

--
Cheers
Dave.