A friend of mine, who is in engineering R&D has recently made me a really nice experimental fireplace door. I fitted it without much effort in about an hour.
I will be taking temperature measurement and experimenting with draught and fuel over the next couple of weeks. I will of course post photos and details here as the experiment runs.
Initial impressions are;
(1) the burn is much better,
(2) radiant heat is well reduced from the front of the fire,
(3) heat to the back boiler is increased substantially.
(4) the door and its frame get quite hot - something you would need to be aware of when adding fuel etc.
Watch this space for further postings.