Need heat in back

[n250jg]

We?ve talked about a second NACA vent on the 8s for hot days, but what have others done to get heat to the rear seat on cold days? A 4 hour trip from Houston to Colorado this winter left us both (but especially Diana) in pretty cold air. We have heated seats but that doesn?t do much for the face, hands, and feet.

In an attempt to get heat to the back seat I set up our system like this:



Air is heated through a muff on the #3 exhaust and controlled with a valve at the firewall. Air from the NACA vent on the fuselage is also controlled with a valve just off the vent. Downstream of both vents is a ?Y? to mix the two streams, followed by another ?Y? to split the air between the two vents on the panel. My thinking was that the heated air would make it to the back seat better if it came through the vents, rather than being dumped in the cockpit at the firewall. I also thought that the setup would allow for mixing fresh air with the heated air to regulate the temperature, but all that did was allow COLD air to leak past the butterfly valve to mix with the COOL air from the heat muff.

Have others found that one heat muff isn?t enough and added a second in series? Once you have HOT air available to the cabin, do you dump it at the firewall or try to route it further back? Any other suggestions? Paul, what is your setup and how did it work at FL210?

[Kahuna]

I do believe I am the only flying 8 with REAR heat. Other to follow Im sure.
Only real challenge is how to get the scat tube to the back.
Here is my solution. And this heat will blast you out of the back.
My wife loves me for it.
Best,

[Ironflight]

I agree Jeff, the stock heat leaves something to be desired (but I expected that, as I have read other comments like this on other folks web sites when I was building). I have the stock heat system - just dumping heat from a single muff out by my right foot on the firewall. I am using the single NACA scoop on the left side split to two metal eyeballs on the panel. Fortunately, they close really well, so that I can shut that flow of cold air off pretty tight.

On cold days, I pull the cabin heat all the way open, and close the fresh air vents. My right leg stays warm. I can feel a prety good chill on the left side. My feeling is that the rear seat is getting nothing at all, except solar heating from the canopy! I imagine that it woudl be uncomfortable pretty quick! If I was livign up north, I would probably add a second heat muff, as many have done.

It was a might chilly up at FL210 yesterday, but since I had a helmet and mask, my head and face were fine - and I was wearing my heavy-weight flight jacket to keep my torso warm. When I took my gloves off, it was apparent that the cockpit temperature was pretty low. If it had been a long trip, I would have wanted some good long underwear for my legs! It was tolerable, but chilly.

(Remember, I grew up flying J-3's on skis in Minnesota, so I might have a little better tolerance for what is acceptable - calibrate my remarks accordingly!)

Paul

[dan]

Originally Posted by Ironflight

Fortunately, they close really well, so that I can shut that flow of cold air off pretty tight.

Don't know about anybody else's vents, but my heat works best if one fresh air vent is slightly cracked open. The little bit of fresh air flow causes circulation and actually gets the heat circulating nicely. With the vents closed, the heat is pretty localized to the footwell/firewall area.

I open my vent just a crack and point it up as high as it will go. Give it a try!

[Ironflight]

Dan - I tried it that way - played with a number of combinatiosn actually, and didn't really see much difference. It might be -8 unique, or is more likely, different with different vents...

I haven't completely exhausted the bag of tricks though - have yet to put some stuffing in the heat muff for instance. Here in South Texas, spring will probably catch up with us in a few weeks anyway, and I'll lose my motivation for experimenting. Then I'm going to want to see Jeff's new vents!

Paul

[rv8bldr]

Originally Posted by Ironflight

--Stuff Deleted--

(Remember, I grew up flying J-3's on skis in Minnesota, so I might have a little better tolerance for what is acceptable - calibrate my remarks accordingly!)

Paul

Hey Paul,

I hear ya ;-) It gets a little nippy up here in Ontario, too. I was up flying yesterday at 5000'. -16C (Somewhere a little above 0F I think)

I took a friends kids up a few weeks ago. -20C at 3000'.

Lots of performance though ;-)

[Alan Erickson]

Jeff, nice diagram - I've working on about the same design. One concern I've had is the possibility of opening the heat valve while the vent itself is closed, causing too little airflow through the muff - with undesirable consequences. Anyone have a good feel for how much of a concern this is? I've considered several solutions; my fave at this point is the simplest one: opening a small unclosable bypass hole just behind the eyeball vent to always provide some minimum muff airflow if the heat valve is open.

I'm also considering running a much smaller-diameter vent tube (e.g. 0.75" poly-tube or SCH40) to a small eyeball mounted on the midcabin brace near the pilot's elbow, prolly running the tube under the throttle quad. Much less airflow than the 2", but much less missing metal as well. One could balance the airflow - with some work - by shutting down the the pilot vent a little. Thoughts?

[jamiller]

I put in two heat muffs - one on each exhaust pipe. Outlet of the right muff goes to the inlet of the left. The combined heat goes to one heat box on the firewall above & left of my left rudder pedal (this to make it possible to route further aft in dedicated scat if desired - haven't done so yet). Don't know how this would compare to just one heat muff.

Performance of my heat system is marginal as is. OK down to about 15F - above; below that it I found extra clothes, gloves, etc. needed. Heat getting to the back seat is sub-marginal.

I have planned a spot on the firewall for a second heat box. I could seperate the output of the heat muffs, having one for the front seat and one for the back. This will require some method of routing a scat to the back seat and I like the method shown on the earlier post on this thread.

Before I go to all that trouble, though, I have another idea I'm going to try first. Since I have the 60 amp alternator and only pull about 15 amps in normal VRF flight, I installed an extra dedicated circuit with its own 10 amp fuse and #14 wire to the back seat. I'm going to try some of the heated clothing made for motorcyclists (such as Gerbing). You can get heated socks, gloves, vests, jackets, pants. Of course, if you tried to hook up all this stuff it would probably be too much current draw, but I think the jacket or vest should be OK. Anybody else done this?

This is an important question for me. It does get a little cold here once in a while.

John Miller
Fairbanks

[ericwolf]

Jeff,

I have been contemplating ways to improve the heating situation on my -8A since I live in Wisconsin.

I did not know that anyone had used heated seats until I saw the thread a few days ago discussing this. A couple people commented that with heated seats, it is comfortable to below zero temperatures. So either you have a different set up or you Texans can?t handle a bit of cold weather.

Seriously though, I am considering a similar system in which hot air flow can get to the back (and to me) somehow. Kahuna did it, but I am exploring alternatives to cutting the big hole in the spar web. I doubt it is a structural concern, but I?d like to avoid it if I can.

Randy Lervold on his website says that when he mounted the heat duct to an eyeball vent under the panel, decent heat reached the passenger. Maybe this is why you have two vents, one aimed and you and one aimed at your passenger?

Would it be beneficial to replace the air cutoff valve and the ?Y? with a hot/cold air mixer? Van?s sells one, but I don?t know how good it is.

[Chino Tom]

God forbid we do anything like the glass guys, but don't the EZ guys use small electric heaters? Haven't looked into that yet, has anyone else?
Heat not a problem in my -6, buy hey winter in SoCal today was more like late spring (85 degrees).