OK, Here we go…

S.E.E.R. is an efficiency rating, much like how miles per gallon (MPG) is used to rate automobile efficiency. We all understand that if you drive 300 miles and consume exactly 20 gallons of gas, then your vehicle’s fuel efficiency (MPG) is 15 miles per gallon (300 miles divided by 20 gallons). A vehicle that gets 18 MPG would be more efficient (less costly) to operate, and a 12 MPG vehicle is less efficient (more costly) to operate. For HVAC, S.E.E.R. follows the same rationale.