I know there are a lot of variables for this, but hoping someone has done this before me and can share their experiences...
I'm in the early stages of getting a new log burner put into a smallish living room (5m x 4m), it previously it had an older Metro Aspire log burner which was rated at approximately 18-20kW max output. The old log burner did a great job of heating the room and some of the rest of the house, without being too over powering. This living room has just been relined, lots of wall and ceiling insulation and double glazing - so should be much more user friendly.
What I'm wanting to do, is take some of the heat from the new log burner and move it around the house. Directly behind the spot where the log burner will be is the return vent for a ducted heat pump, this return vent is mounted in the ceiling. My plan is to add opening near ceiling level behind the flue to allow hot air to flow directly into the heat pump return, and hopefully then just run the heat pump in circulation mode to move the air about the house. The return vent duct is 400mm in diameter, so there is an opportunity to move a fair bit of hot air about the place.
What I can't get any sort of feeling for is how much heat I can expect to move this way. One guy in the heating industry suggested 2kW at best which sounds like it would be hardly worth the effort.
If the heat transfer system could move, say 5kW of heat, then I’d look to buy one of the bigger log burners available, something around 24kW. But if the transfer system will only move 2kW of heat, then this will be far too big for the small room.
(the heat pump itself is an older one and is useless when it's cold outside < 4 degrees, 1950's house, poorly insulated, about 240m2 in total)
I'm mostly leaning to get another mid size log burner - say 20kW like the old one, but if this system could move a lot of heat, then bigger would be better.
What to do??