Heat through cabin vents

[TravisHamblen]

Up here in Minnesota it can get QUITE cold, so I am always looking for more cabin heat. As a matter of fact I built the RV-7A while living in Las Vegas and I laughed at needing any heat. Now that I am in Minnesota I am planning to install a second heat muff so I can get as much hot air flowing into the cabin as possible. With just one heat muff and some REALLY cold OATs the cabin is just okay, if you have on all your cold weather gear, but not even close to toasty warm. With the heat coming out down by your feet it seems to keep my feet nice and toasty, but the cabin up by chest level is COLD!

So my plan for the 2nd heat muff is to route it up into the fresh air cabin vents (eyeball style) so that it can be aimed wherever I want the heat at the time and you can even adjust the flow volume (although I don't see much need for anything other than full blast this time of year). I was struggling with the idea of making a selector box under the panel for each vent so you can swap between cold air and hot air. For now I am just going to run the heat straight up to the vents, then twice a year I can swap which hose I hook up to the vents. I am hoping that this will heat the upper portion of the cabin up to a toasty warm state and the original heat muff will continue to keep the feet and area below the panel toasty warm. I shudder just thinking about what it would be like to fly with it Minnesota cold outside but nice and warm in the cabin, especially being able to aim those vents around, and maybe even put my hands in front of them every once in a while for a nice warm up!!

Has anybody done this before?? If so what kind of results did you get? Any advice or suggestions would be greatly appreciated!

Travis
RV-7A 45+ hours
Lake Elmo Airport

[Norman CYYJ]

One of the things you can do to get rid of the cold is to block the holes in the rear baggage bulk head. That will stop a lot of the drafts and also put boots on the push tubes out to the wings. It will much warmer.

[TravisHamblen]

Originally Posted by Norman CYYJ

One of the things you can do to get rid of the cold is to block the holes in the rear baggage bulk head. That will stop a lot of the drafts and also put boots on the push tubes out to the wings. It will much warmer.

I have most of that under control pretty well, although I have some ideas for fine tuning it even more. The problem is that when its -15F you REALLY need two heat muffs to get the ambient cabin temp up to around anything tollerable for long flights.

Travis

[L.Adamson]

Assuming you'll have a cable operated selector box to turn the heat on & off; I'd just run a pipe or two (tee'd) under the panel pointing horizontally, and let it go at that. Fittings on the ends are optional.

You're still going to have about the same amount of ducting anyway, and then you won't have to make yearly changes at the eyeball vents.

And should you need fresh air for some reason, you'll still have it.

I'm a heating/air conditioning contractor, and I just hate making changes to ductwork between winter and summer...

L.Adamson

[N941WR]

Travis,

One recommendation I was given was to use 2" exhaust wrap on just the heat muff.

[TravisHamblen]

Originally Posted by N941WR

Travis,

One recommendation I was given was to use 2" exhaust wrap on just the heat muff.

What does it do? I think I have seen people who have wrapped their entire exhasut system, never understood what it was for. If you have any product info as well please post it.

Thanks,
Travis

[TravisHamblen]

Originally Posted by Deven

I got behind on projects this fall and what you describe is about what I did. I only have one muff but it is plumbed to one eyeball vent after coming off the aft baffle. I haven't tested it to -15 but +15 is fine for me with warm clothes. I would like to build a selector box also but if I get behind again and feel the need for some air time its easy to pop the cowl and swap some scat tube.

Well luckily I have only flown once at -15f, it was in November I think. It wasn't too bad in flight, but when I landed at a neighboring field to get fuel I sure wasn't too happy getting out to fuel up. I got feeling back in my fingers after a couple minutes back in the cabin, but man -15f is REALLY cold (did I mention I moved here from Las Vegas, previous to Las Vegas I lived in Tucson, and previous to that I lived in Phoenix). But I sure do love Minnesota!

Travis

[Gerald Clabots]

Theres a company in Mn. that makes 4 into 1 exhausts. I talked to him at Oshkosh and he can spot weld studs to your exhaust pipe where your heat muff wraps around. This will give you more heat out of your present setup.
You should be able to find him on the internet.
If not I'll try contacting someone I know who had it done for his RV-7.
Gerry
7A N742GC

[Bevan]

I heard of some who install 2 heat muffs. If this would help, would you plumb them in series or parallel?

Bevan

[TravisHamblen]

Originally Posted by Bevan

I heard of some who install 2 heat muffs. If this would help, would you plumb them in series or parallel?

Bevan

Parallel, don't know that series would make as much of a difference.