I installed the first one myself with a open flue "old coal fired chimney"
I had a HETAS installer sign it off .
All the relevant boxes were ticked .
Air brick installed , Co monitor .
The chimney was professionally swept and smoke tested .
The lad that inspected it said that the register plate...
The one I reviewed is still going strong .
It is more of a talking point than anything else .
That being said you can feel the warm air being blown out of the alcove .
I will have a play with a thermal camera .