Question: what btu heater for garage?
Answer: A basic rule of thumb for forced-air heaters is 45,000 Btu to heat a two- to 2-1/2 car garage, and a 60,000 Btu garage heater for a three-car garage. The makers of low-intensity infrared tube heaters say that 30,000 Btu can heat a two to 2-1/2 car garage, and suggest 50,000 for a three-car garage.