My garage is 24ft 1in x 24 ft 2 in, I have a 15ft 10in 6ft 11in insulated garage door, the ceiling when finished will be about 9 ft 2in high and I got a cement floor, I just bought a 75,000 btu heater, is that too excessive? Does anyone think I will be better off with a 45,000 BTU heater...