Need heat in back

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?

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,

Glad I'm not flying it back home in a Minnesota Winter!

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

crack the vent open

Ironflight said:

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

Click to expand...

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!

Cracking the vents

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

Ironflight said:

--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

Click to expand...

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 ;-)

concern: muff flow when vent closed

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?

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

More thoughts

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.

Electric heater....

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).

Simplify

Jeff, I think the first thing I'd try is to simplify the system. Part of the problem may be that the hot air is losing energy as it passes through the valves and diverters. Also, the cold air to the mixer is going to steal heat from the hot side even when the valve is closed because it's refrigerating the valve itself. The eyeball vents might be a problem, too, if they're smaller than the 2" scat tubing.

But the most important thing is, once you get everything re-routed -- give Diana the diverter control knob.

Long reply

Here comes a mass reply to everyone:

Dan ? We?ll try that once we get hot air coming into the cabin. The day we left it was 30F on the ground at Houston and 10F at our destination and the vents were already leaking, so at the first stop both NACA scoops had rags stuffed in them.

Alan ? If you use the heat box from Van?s, when you close it to the cabin it is open to the engine compartment. Air will always be flowing through the heat muff, you just decide where to direct it. We used something similar to the TG-10. The door is hinged on the right, the bottom is mounted flush to the firewall, the air from the heat muff comes in from the left, and the air is dumped overboard out the right when you close the valve.

You also might want to test the smaller tube before you install it? I would be afraid that it?s too much of a restriction for the air. The vents on our panel are fed with 2in SCAT, but the smaller 1? (maybe even ??, I can?t remember) vents don?t put out near the amount of air that the larger 1 5/8? vent in the back does. Maybe someone local that?s flying will let you do a test? use something to make a doughnut shaped seal to fit inside the existing SCAT in the test plane and hold your ?? tube in the center (pipe in a pipe).

John ? We might try the heated clothing too. I?ve got a 40 amp alternator and so far this has been plenty? normal flights during the day draws about 11-12A and each seat heater increases that by about 5A. If you go that route, let me know what the current requirements are for the jacket or vest.

Eric ? Diana (born & raised in Corpus Christi, TX) was definitely colder than me, but after living here 4 years I?m finding that cold temperature aren?t as tolerable as they used to be. I?m either getting acclimatized or not as tough as I used to be.

I?m not sure how Van?s hot/cold air mixer works, but I?m thinking my home grown should work about the same. In theory mine would have a full stream of heated air when the heat valve is open and then a variable amount of cold air can be added to the stream with the butterfly valve. Here?s a couple pictures of the butterfly valve and the assembled unit:



Jon ? Simplification is a great idea and I should have probably started with that for a base case. I?ll have to try a couple tests 1) with a straight shot from the firewall to one vent and 2) just dumping it at the firewall. Giving Diana reign over the heat knob might not be a good thing though ? she thinks cold is below 75 degrees!

Heated Vests

The wife and I are both avid motorcyclists and often take trips like this one from New Mexico to here:

One thing we've found invaluable is heated vests. They don't draw much current and beyond adding an outlet at each seat, you don't have to modify the plane. At least on a motorcycle, heated vests help keep your entire body warm just by keeping your torso warm.

Several people make heated vests. I'm convinced the best come from Aerostich. http://www.aerostich.com/home.php?cat=284 . Aerostich vests have a heated collar that keeps your neck toasty warm. It seems like that's just the thing for the drafty back seat of an RV-8. I think that the small BMW type plug is the superior connection. Those are readily available here: http://www.powerletproducts.com/

I'm not associated with any of the companies mentioned above.

Power outlets

Guy Prevost said:

I think that the small BMW type plug is the superior connection. Those are readily available here: http://www.powerletproducts.com/

Click to expand...

Those are very cool!

n250jg said:

...Alan ? If you use the heat box from Van?s, when you close it to the cabin it is open to the engine compartment...

Click to expand...

Thanks for the reply, Jeff. I'm talking about the case where heat is demanded, so the muff air flows into the heater plumbing, not the engine compartment -- but you've got the eyeball vent closed (mine has a 'closed' position), so the muff is blocked. Just something to watch out for, I think.

Thanks for the thoughts on small heater tube - I'm thinkin' I may ditch the idea; it does sound like it won't be terribly effective. I'm starting to really like the heated clothing idea, though! (thanks for the link, Guy)

One RV-8 solution

http://bidasst.bizland.com/heatvent.htm

He felt haveing a good positive vent OUT the aft cockpit area would draw heat to the GIB (Gal or Guy In the Back). You can't pump more (hot) air in if you can't get it out! Am I right.

The other solution is build a RV-7

George

oil cooler

has anyone tried to put a small oil cooler in the cabin the tubes can be much smaller like maybe 1in and you can put a small fan on it to move the air.

Robby Knox has a electric heated seat in the rear of his plane and I would have froze on the way out to LOE if he didn't have it.

Guy Prevost

Vest looks great! Ordered one for my wife. Thanks much. Bill

Chino Tom said:

God forbid we do anything like the glass guys, but don't the EZ guys use small electric heaters?

Click to expand...

IIRC the EZ guys used some sort of hair dryer to make heat. A quick web search turned up quite a few 12V hair dryers in the $15-20 range. Anybody considered a roll-yer-own electric heater using one of these?

It's 11 degress out right now, so I'm thinking a lot about heat in the new bird.

Jeff, I live in the Colorado rockies so I have been thinking of a way to get heat to the rear seat also. I know that my wife and others would appreciate heat at 12,500'msl on a winter cross country flight. I wish Vans would engineer a larger hole thru the spar center section for this purpose, but until that happens i'll keep thinking on it. My latest idea is to bring a shallow but wide duct over the top of the spar center section but under the front seat cushion. I think it might be possible to raise the front seat cushion as much as 1" above the sloping seat pan to create room for this duct on the left side of the seat. It is hard to know how much heat will remain after losses in ducting. Might end up with a real hot leg! Unfortunately I have never flown in an RV8 so I have no idea of bad this problem is. It sounds like airflow out of the cockpit could be a key factor to getting heat to flow in. Tony

More items

And for additional passenger comfort check out these items for your 'back seater'. 12 Volt Items

Thanks for the link...

My wife now wants the "pop corn popper" to go with her DVD player for those 3 hr. +++ legs!!
Mike

Progress made?

Last post on this was almost three years ago. Was wondering if anybody has figured out a solution using heat muffs (ie excluding seat heater and motorcycle suits) to help keep things warmer in the back seat? Does anybody know where one can get a 2" "Y" with a diverter in it? I would like to use a heat muff 2" tube from the firewall that Ys where the naca scoop 2" tube is and goes to the 2" vent on the panel. That way I can open the heat valve on the firewall and vary the mix at the Y from the naca scoop. Any thoughts or ideas would be appreciated. Thank. Dave

Rear heat from a second heat muff in the 8.

Thanks

Thanks for the reply Mike. I have seen that and, nothing personal, but I don't feel compartable cutting into the spar box. I think if I can use the 2" panel vent with heat aimed to the rear (on the first heat muff), the other heat muff dumping the heat into the cockpit from the firewall, and set heaters, I'll be ok. I just need to figure out how to use the panel vent to use both heat (aimed to the rear) and cool air in the summer for me (since the rear has their own cooling vent). Dave

This was really helpful, thank you.

James Hawkins

I have looked at this and have decided to install a heated rear seat therefore only wires to run.

Rob

Rear heat

I decided to have seat heaters AND heated vests (front and back); therefore, nobody will get cold. I also have two heat muffs with two seperate heat inputs (near rudder pedals for feet and a Y into the vent system on the left side of the instrument panel -- it required another valve to close off the NACA vent). Better to have too much heat that is controlable, than not enough. Dave

heat the floor

Anyone try just getting heat through the spar area so that it flow under the floor area, it seems this would hear up the floor area in the entire cabin and then it would radiate up through the cockpit. I am thinking this along with the traditional heat vent. One might be able to fashion tubes that attach to the opening for the control stick pass though that would still not interfere with the stick movement.

Maybe the amount of heat would need to be too great to overcome the cold bottom of the fuselage. My other thought is a removable duct that would "Y" off the main heat vent, this way when a rear passenger is a aboard you just run the tube to the back and keep it out of the way with zip ties. I know most of my flying will be solo so for now I just plan heated seats and will try the heated vest deal.

Not sure but perhaps a heated seat element under the floor would heat the floor enough, like heated floors systems for houses.

Cheers

Rear seat heat

Haven't decided what to do yet, outside of heated seats and vests, wired. But Jim Phillips heats his foot area as usual and then hooked a second muff to scat tube which can be routed to rear seater over his (or her, the rear seater) foot. Seems to work fine, and can be directed elsewhere if no one's in back. I too am uncomfortable with cutting a big hole in the spar web. Perhaps Van's could do a stress analysis and come up with a safe place and hole size to transition heat through the spar area.

Heated vest works great

Quote: 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? Quote

------------------------------------------

I have an RV-8 with a 60 amp alternator and wired it for use of an electric (motorcycle) vest. Like many of you, my standard one-muff heat system is not adequate for high-altitude or winter flight in the Pacific Northwest. My wife likes to wear the heated vest on most of our trips. I only use it when solo and when it is really cold. With an outside jacket over the vest, wind pants, and gloves, I am comfortable in very cold conditions. I am sure that my electrical system could handle both a heated vest and pants. Give it a try.

Dan Miller
RV-8 N3TU 680 hours

Jeff,
I'm just getting ready for the first flight in our -8. I live in Colorado and have heard the stories about the "Ice Box" in the back seat of an RV-8. My solution to the problem is probably unique to my airplane, but I thought I would share it anyway. I had Larry Vetterman build a four pipe exhaust. This allowed me to put a single heat muff on one pipe for the front heat down at the rudder pedals. I then put a double heat muff (Rick Roobins made it for me) and plumbed it to a second heat valve below the Battery Box (lower right side of firewall). Because I have a "Glass" panel, I have all of my switches and breakers on the instrument panel. This allowed me to come though the lower right compartment in the baggage area to a 2" bulkhead fitting on the right bulkhead just forward of the right gear tower. I then built a plenum to run along the right side of the cockpit to just aft of the crossover bar. The plenum has a defuser on the end that will distribute warm air in the back seat. It is activated by a standard push/pull cable on the right gear tower. It also creates a map/glove picket out of the right side angle deck behind the gear tower. This is all still unproven until I fly her for the first time, but I think it should be very effective! I will post my findings on this system as soon as I land. Hope this gives you something to think about.

Paul "Ox" Harder
First Flight very soon!

Pics from Paul?

Paul-

I sure would like to see pics of what you did...sounds very interesting! Will be looking forward to hearing how well your setup works!

I have the Gerbings heated jacket liners with heated turtle neck. these have additional wire connections for heated pants and gloves.
After enjoying that while motorcycling for several years, the wife and I added the heated gloves.
You can't go wrong with this. The liner fits under the 'De Rigor' flight jacket or flight suit, so no harm, no foul.
The power draw is low because the liner fits under your outer clothes. Wire is much easier to pull and find space for than scat tube, distribution boxes and eyeball vents.
You only need this heat a few months per year, why carry that heat system weight around the rest of the year when you don't need it?

Solution to needing heat in the rear cockpit

I have completely solved the problem with a lack of heat in the rear of the 8. I loved my 8A. I thought it was the best flying machine ever built.
Some background: I sold a half interest during the construction phase. After 18 months the other member of the LLC wanted out. Rather than buying his share we sold the 8. I replace it with a 6A. No more cold, unhappy wife. She is warm and comfy up front with me. The 6 flies much like the 8. The only disadvantage is the view off the right wing is not as good as on the 8.

Ouch!
That was cold!!

any chance of pictures of this?

Paul,

I'd love to see pictures of this setup.

Paul "OX" Harder said:

Jeff,
I'm just getting ready for the first flight in our -8. I live in Colorado and have heard the stories about the "Ice Box" in the back seat of an RV-8. My solution to the problem is probably unique to my airplane, but I thought I would share it anyway. I had Larry Vetterman build a four pipe exhaust. This allowed me to put a single heat muff on one pipe for the front heat down at the rudder pedals. I then put a double heat muff (Rick Roobins made it for me) and plumbed it to a second heat valve below the Battery Box (lower right side of firewall). Because I have a "Glass" panel, I have all of my switches and breakers on the instrument panel. This allowed me to come though the lower right compartment in the baggage area to a 2" bulkhead fitting on the right bulkhead just forward of the right gear tower. I then built a plenum to run along the right side of the cockpit to just aft of the crossover bar. The plenum has a defuser on the end that will distribute warm air in the back seat. It is activated by a standard push/pull cable on the right gear tower. It also creates a map/glove picket out of the right side angle deck behind the gear tower. This is all still unproven until I fly her for the first time, but I think it should be very effective! I will post my findings on this system as soon as I land. Hope this gives you something to think about.

Paul "Ox" Harder
First Flight very soon!

Click to expand...

I think George (Post #16) is onto something.

I added a tail vent to my sailplane this year - for different reasons - and was shocked at the increase in vent air flow, and how much quieter the cockpit became due to elimination of all of the vent air having to find its way out around the canopy etc.

If there is no 'air outlet' vent, it seems that the heat and inlet air are constrained to the summation of all of the leaks that exist?

Not flying yet so...

zspivey said:

I have completely solved the problem with a lack of heat in the rear of the 8. I loved my 8A. I thought it was the best flying machine ever built.
Some background: I sold a half interest during the construction phase. After 18 months the other member of the LLC wanted out. Rather than buying his share we sold the 8. I replace it with a 6A. No more cold, unhappy wife. She is warm and comfy up front with me. The 6 flies much like the 8. The only disadvantage is the view off the right wing is not as good as on the 8.

Click to expand...

Yeah!................but now you're flying a six not an eight. That's way too much to give up!

Easy Heat in the back of an Eight

If you didn't put the battery on the firewall, then there is room to install your heat box where the outlet will enter the forward baggage compartment just below the shelf, and against the vertical wall. From there you can run the two inch scat tube to the upper inside backwall of the forward cargo compartment to a 1 1/4 inch adjustable air outlet. The heated air can be directed to blow along the right side of the cockpit, past the pilot, and directly to the back seater. It blows so strongly that the back seater can hold a hand up and feel a steady breeze of warm air. The air seems to circle back up the left side of the aircraft to the pilot. It works really well, and is simple to do.

SHIPCHIEF said:

I have the Gerbings heated jacket liners with heated turtle neck. these have additional wire connections for heated pants and gloves.
After enjoying that while motorcycling for several years, the wife and I added the heated gloves.
You can't go wrong with this. The liner fits under the 'De Rigor' flight jacket or flight suit, so no harm, no foul.
The power draw is low because the liner fits under your outer clothes. Wire is much easier to pull and find space for than scat tube, distribution boxes and eyeball vents.
You only need this heat a few months per year, why carry that heat system weight around the rest of the year when you don't need it?

Click to expand...

Glad I found the posts on electric heat... I've been tormenting myself about airplane heaters for some time now and this is exactly the solution I came up with. Electric clothing when needed, no extra weight to lug around in the summer - a much better solution than miles of leaking SCAT tubing directing exhaust gasses into the cabin. For the next project, electic clothing will replace the cabin heater, just as ANR headsets replace sound deadener.

Good stuff!