Many many thanks to all those helpful posts - and good to see people enjoy what they do too. In response to request for sizes, here are room sizes.
Room size examples:
Lounge - 3.45m x 4.25m x 2.5m high, two external walls of 18inch stone & rubble, 3.2m of double glazed and draughtproofed sash, timber floor with space beneath. In here he has placed a Stelrad K2 compact (450 x 1200mm) which gives about 5615 BTU
Dining - 3.45m x 4.2m x 2.5m high, one external wall, one single glazed window into the conservatory (so not really a window). In here a compact stelrad K2, slightly smaller, 450mm x 1100mm, giving about 5100 BTU
Kitchen - I wanted to get a rad and the installer didn't calculate what I'd need. I got a vertical semi designer thing from B&Q (i know, i know, but it was a weak moment) giving 2800 BTU. Looks alright but gurgles if turn TVR up beyond 3. Kitchen is 2.7m wide x 5m long x 2.2m high, one small double glazed window, one external wall (short side) and one wall has a door and window into the conservatory (antarctica).
Conservatory - a few installers who quoted suggested not trying to fully heat the conservatory but I though to put something in at least to take the edge off the cold. I suggested something under the interior window, so he put Stelrad K2, 300mm x 1500mm giving 5026 BTU. It's 2m x 5m long, and over 3m on high side. Also, that rad is teed off the dining room rad flow & return, not from the main flow/return circuit.
Hall & upstairs landings - incl stairs it's about 15 to 16 m long (horizontally) x 0.9m wide x 2.5 m ceiling. No outside walls (just party walls) or windows. There is one K1 downstairs (600mm x 11000mm = 3678 BTU) and one upstairs (600mm x 900mm giving 3009 BTU)
Master bed - 4.35m wide x 4.2m long x 2.4m high - he put in a K2 600 x 1000mm long, giving 5910. There are two external walls, like lounge, and three single glazed sashes but all secondary glazed so no draughts. There is about 75mm of loft insulation.
2nd bed - 2.55m x 4.2m x 2.4m high. Rad is K2, 450mm x 1100mm = 5100BTU. Two outside walls, one double glazed window, roof space insulated with 75mm insulation.
Bathroom - installer was arguing that I asked for a towel rail which he pointed out isn't as powerful as a panel radiator. I pointed out I never told him how big to make the towel rail! He installed one 500mm x 1200mm giving only about 1400 BTU. Bathroom is about 2.7m x 2.3m x 2.2m high, two external walls, one double glazed window.
Study - small room about 2.2m x 1.7m x 2.2m high. No radiator, just the boiler. One small dg window, one external wall.
That's it, so about 37600 BTU of radiators in house. Sounds like I need ask if he limited the boiler heat output yes?
