Water heater is 6000W
Air con I do not know.... But, Bedroom one is 12 sqm floor area with an 2.5 metre ceiling. I was going to buy 9000 BTU... Saw a 7000BTU (Samsung) on special in "Global House, Lamphun" if that would suit a 12sqm floor area (About 30 cubic metres)... I would save money. It is priced at 8990 Baht.
May suit 2nd bedroom as there is a lower ceiling. Same floor area 12sqm but, only 24 cubic metres.
Lounge/passage is 38 sqm facing west (afternoon sun) about 90 cubic metres. Not sure of "optimal" BTU required here? Will research.
Unless there is a "guru" on here who can genuinely advise, both efficiency and running cost.
Ennis