what i suppose to used to convert rpm to m/min for a round tube? inner diameter or outer diameter? inner diameter is 31.3267m and outer diameter is 38.3267 mm.
Try calling your local utilityIn some areas they perform a free infrared test on your home to help determine where you are losing heatYou failed to mention what type of insulation you have in the ceilingThat's where you will lose a lot of heat since hot air risesYou should have at least R-30 in your attic.
I agree with sparky as I also live in Michigan.It sounds like the walls are not the problem.The attic and the windows are the key.I built my own home,but used cheap windows and not enough insulation in the attic.Corrected the problem,and yes it will cost,but will save money and pay for self in long run.
