Cabin heater coolant diagram

[AvDES LLC]

i have just crossed the 100hr threshold with this setup in my plane and it provides plenty of heat to keep myself and my lady warm in the Reno winters. It does get a bit toasty in the spring / summer months and to solve that I simply put a ball valve on the inlet line. When it’s hot out, close the ball valve and zero coolant flow takes place through the exchanger.

[bbs428]

I weighed a new 8" rad. fan I was thinking of using. It blows a lot of air but it's 1lb 13oz. Plus the amp draw. Ouch!

I think I'm warming up to your shroud. Weight would be miniscule compared to the bigger, stronger fan plus the savings in amps.
I might be able to bend up some aluminum sheet but not sure if it would look as good. I don't have much in the way of sheet metal tools/benders/brakes.
My heater core is 8"x 8" so I'd have to make my own variation. Now would be the time to do it!

Is that 3" hose from the firewall to the shroud?

Thanks for posting - really got me thinking in a different tangent.

[AvDES LLC]

Glad it got you thinking outside the normal box. These engines don’t have much for electrical output and sucking some up with a big fan isn’t always the best idea in my
mind. If you want to aim more for the “certified” approach, you can run a small 2 inch duct to a muffler shroud and have the outlet to that shroud go into a through bulkhead ducting port and into the shroud on your cabin heat heater.

drop me a pm if you want to discuss shrouds and whatnot. I can steer you in the direction of a possible solution to your dilemma.