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I built a cabin heat setup, and now that winter is set in I have had the opportunity to use it. Now, we all know just how "well" a VW engine is known for providing heat ;) , but I was hoping for at least a little better than I'm getting. Here's my basic setup:

http://www.mykitlog.com/users/display_l ... 758&row=73
http://www.mykitlog.com/users/display_l ... 290&row=41

Air comes in the upper cowl, goes through some SCAT tubing to the heat muff, then out the muff and to a firewall flapper valve. The air intake at the cowl is a 2" hole, but I quickly found that was WAY too much air. So through trial and error I got down to a blank off plate that has a 1/4" dia hole in it. Any larger than that and all the air that comes to the cabin is cold.

I'm in the process of making a new heat muff that will have fewer seams and holes, to try to keep air from leaking out. I also plan to wrap it with header wrap to keep more heat in. I will also wrap more stainless springs around the exhaust, trying to get more heating surface area. And finally, I plan to make the muff removable so I can inspect the inside at the annual condition inspection.

I'm wondering if anyone has had better success with a heating system that works (or at least works better).

PS: Interestingly I found that even with a 2" hole in the back of the baffle, and the flapper valve wide open, even in the summer that had NO effect on the CHTs on either side of the engine.

Thanks,

Disclaimer: I have never made a heat muff. Yet.

The problem with springs is they are not going to get super hot, in my opinion. What if you made a screw on aluminum heat sink out of sheetmetal? Make a tube, flush rivet angles onto it. They can be thin. Use heatsink compound between the angles and tube. Also use it between your aluminum tube and the exhaust. Keep volume to a minimum as extra volume will just pass cole air. I would try and make the outside of the muff a tube as well.

I will have to make sketches sometime. Hard to do that on the phone.

Just remembered that I still had the old technology.

Hastily drawn!

Bryan, would the aluminum stand up to the heat of the exhaust pipe when there's no airflow (cabin heat turned off)?

Rynoth wrote:Bryan, would the aluminum stand up to the heat of the exhaust pipe when there's no airflow (cabin heat turned off)?

My current muff is aluminum. Even in the summer I keep a small amount of air going through it to keep it from overheating. So far no ill effects on the aluminum, but the new heat muff is going to be stainless steel.

Bryan Cotton wrote:Disclaimer: I have never made a heat muff. Yet.

The problem with springs is they are not going to get super hot, in my opinion. What if you made a screw on aluminum heat sink out of sheetmetal? Make a tube, flush rivet angles onto it. They can be thin. Use heatsink compound between the angles and tube. Also use it between your aluminum tube and the exhaust. Keep volume to a minimum as extra volume will just pass cole air. I would try and make the outside of the muff a tube as well.

I will have to make sketches sometime. Hard to do that on the phone.

The final box needs to be a square tube to get the fitting onto the body for the SCAT tubing. What you sketched for the interior would certainly grab more heat, but it's a lot of work :) . I think I'll try the added stainless steel springs first. If that doesn't work then I may try something more elaborate. Thanks for the input! That's what's great about the Forum.

Ryan,
All the certified airplane cabin heat setups always keep the air flowing, but dump it forward of the firewall when it is off. Most aluminum heat muffs will die eventually. May take a few thousand hours though.

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Bryan Cotton wrote:http://www.chiefaircraft.com/aircraft/windshields-vents/cabin-heat/la-hm1.html

Too expensive, and the AeroVee is 1-1/4" exhaust. But it gives some good ideas for making our own! I wondered about some kind of baffles to slow the air down. Maybe I can incorporate that concept.