Backpressure On A Squirrel Cage Blower

Yes. You can't push air with a vacuum, or transfer heat. It's better to shove those air molecules closer together with pressure to carry away the heat.

I'm sure there's some fancy gas law/heat transfer formula that describes this, but that's how it worked back on the farm.

True of the heat transfer thing, so hmmm on that part. maybe worry about that later, right now want to get the max CFM through the panel possible.

Joe

It's always easier to blow air Look at your home furnace with small ducts on the discharge and very large and usually short ducts on the suction side

You can search for spec sheets on furnaces and see the recommended static pressure limits on the furnace or go to www.lauparts.com to download specs on their fan blades or blower wheels and see that the highest pressures are rated on the discharge side but some equipment mfgs do put the cooling coils on the suction side

I built a 4x8' hot air solar collector many years ago with a 6" 5 blade propeller with a 9 watt motor that was rated at 600 CFM (I believe at the time) then measured the temperature rise across in to out temperatures then multiplied by cfms on a psychrometric chart to get btus gained from my personal education project and to my surprise I was getting very close to the same btu output of sunlight Good Luck

And I should also tell you that I'm sorry to admit it but I gave up on building more collectors when I found out due to my one panel research project that I would need to cover the whole south half of my roof on a rancher type house just to gain 100,000 btus during the noon hour without tracking

There is a slight advantage to blowing, because the blower will be taking in cool, relatively dense ambient air, while an exhaust fan will be taking in hot, less dense air. If it weren't for the heating, there would be no difference at all; a pressure drop is a pressure drop.

How much does the pressure heat the air. Then less delta T between the air and the fins. A standard 4x10 solar hot water panel will do 45,000 btu a day, at up to 200 F.