Can anyone give me some guidance on how to work out where to locate a chimney canopy/hood above an open fire? I.e, is there an optimal distance it should be above the fire?

We've just moved in and had to have the chimney inspected as a condition of insurance (it's a thatch) which revealed that it isn't lined so we're not allowed to use the woodburner. On the plus side we are allowed an open fire and don't have to have the chimney swept twice a year but only once, we can cook on it and we can flog the woodburner. We've acquired a fire back, fire basket and chimney canopy which is made of steel and will pass through the registry plate once I've cut the required hole in it. I just need to know if there are any rules that govern how high above the fire it should be.

I take it that would have to be a ceramic or concrete lining rather than just flexible stainless steel? If it were me I would still be looking at ways (if I had to burn solid fuel) to ensure that I *could* use a stove. Comparative efficiencies are possibly as low as 10-20% with an open fire and say 70-ish-plus-ish for a stove.

http://www.soliftec.com/openfires.htm

That would depend partly on whether there was a plate to close off the chimney at the bottom when not in use?

Also I think it's missing the point of an open fire. No one pretends its purpose is to efficiently heat the whole house. There are better ways of achieving that. The point is to provide an intense focus of radiant heat in one room for the time it is lit. If you are cold even a bonfire outside is welcome.