RV-8 Cabin Heat Mod

I decided to try improving my cabin heat distribution in my RV8 to allow more than just my left foot being roasted…..

I did the same thing as Jerry (Widget) Morris - only different..

I'll try posting pics, but I'm not very good at it, so bear with me. I'm looking for comments and warnings about things I may not have considered, that may make this unsafe - like not having a fresh air vent to the front seat for the winter. I figure I can reach behind me and open the back seat vent to get some cabin ventilation if needed.

Here's what I did: Removed the scat tube from the NACA vent on the left side that supplies air to the front seat eye-ball vents. I have a 'Y' tube which allows me to have two eye-ball vents on my IP for the front seat. I get a very strong blast of air from both of these in flight. I connect this 'Y' tube to the cabin heat valve located on the firewall. My cabin heat valve has a flange that protrudes into the cabin. On this flange is another 'Y' tube that supplies heated air to the IP eye-ball vents through the aforementioned 'Y' tube, and to a short piece of scat that heats my feet. I also cut some holes in the scat tube that goes between the two 'Y' tubes for even 'feet heating'. The NACA vent in the fuselage side is sealed with a piece of blue foam (Home Depot) that I cut and sanded to shape and wrapped in Al duct tape.







How does it work? Well yesterday, the OAT at takeoff was -6 C. I went to 5500' where it was a bit colder and figured that would be a good test. The heat for me in front was definitely better, with even distribution on my feet, and a very good flow of hot air coming from both vents. I'll have to wait until I get a back seater to get the final results from there, but just feeling in the back with my bare hand makes me think it will be a huge improvement over what it was. I can aim the eye-ball vents down and the hot air blows on where my GIB's knees will be. It is much warmer feeling than it was before, so maybe this and a heated seat pad will be good enough. squeezing off the eye-balls controls how much heated air goes where. I have two heat muffs in series feeding one firewall mounted heat box.

Cool (or rather Warm) idea!

So in essense you repurposed the fresh air scats for heat. I like the idea of poking holes in the scat near your feet; simple and cheap solution. Prolly takes only a couple mins to convert back to warm weather mode? Let us know your GIB's feedback from the backseat.

At the risk of getting too complicated, I wonder if its possible to mix outside scat with heat scat in a Y (and adjust the outside flow somehow) to get temperature controlled mixed air blowing harder through the IP vents.

At the risk of sounding motherly;
I think the fresh air inlet should be open-able for safety. Even if you just have a string so you can pull the plug out in an emergency.
If you get smoke in the cockpit, you would want that huge blast of clean air.

Heat Mod

You should buy the more expensive aluminum eyeball vents. The close of the airflow really well...I fly in cold temps so I know how well they work.

I have the more expensive aluminum eyeball vents in my panel and in the rear seat area and they close up very tightly, as you say. The butterfly valve I bought is operated via a cable, which would be necessary if it was mounted to the NACA outlet. However, you've given me an idea. I could use an aluminum eyeball connected to a length of scat on the NACA and tie wrapped somewhere within reach to be used in an emergency. A cheaper solution would be to carry a piece of wood dowel, or PVC tube that I could just use to punch out the vent plug in an emergency.

Image links seem broken...

hot & cold air thru vents?

Hi there,
I'm researching about this matter for the kit I ordered, and I wander if there's any reason why noboby installed a selector valve to select hot or cold air and use the panel vent or vents...
I saw the picture below and noticed the scat tube for hot air is not far from the Naca vent...
Isn't there any chance to put a hot/cold selecting box just before the panel vent? it may easily fit screwed to the Naca vent...

I fly in Widget's airplane on occasion and like my RV-8, it is the air leaking in from the rear of the canopy cowl that also needs to be fixed if you want the person in back to stay warm. Although these planes are all built slightly different, I think they may all suffer from the canopy lifting/or just the canopy skirt spreading very slightly and the outside air rushing in due to pressure differential. This is OK in warm conditions, but winter is a problem. BTW, Jerry's plane is certainly a lot better with the change you mentioned, except for the cold neck. Yes, a scarf helps.

Not to change the subject, I just think there is more than one item to take care of to really fix the rear seat environment.

A very timely thread, as my wife Amy was asking me about cabin heat in the RV-8 just this afternoon. Since I'm nowhere near that point in the build, this provided some preliminary answers to both our questions.

I have a "heat box" at the NACA that has a valve that feeds fresh air. There is a heat box on the other side of the firewall that has a valve that feeds hot air. Each has a push/pull so I can vary the temp from all fresh to all heat. I have a "Y" after the inner box that splits to the two panel eyeballs. I am thinking of adding a second heat muff and heat box with "Y" to my feet between the pedals and to a SCAT that runs up behind the panel, under the right arm rest to the back seat, terminating in an eyeball under the rear armrest. My side panels are extra wide and tie directly into the instrument panel at a 45 degree angle. I also have seat heaters.

GIB - "Please turn down the heat!"

Here's what worked for me:
- Vetterman exhaust with 2 mufflers and cabin heat shrouds
- 2 stainless air valves
- Left side valve direct through firewall with diffuser
- Right side valve to scat through lower baggage to bulkhead flange into cockpit
- Cover rear canopy bow with .020 sheet
- Self stick D weatherstrip on front turtledeck below rear canopy cross member
- Self stick 1 1/2" square foam insulation in front of D weatherstrip
- Loop velcro stuck under canopy skirt near bottom and rear edges

I got my wife a heated vest but it's never been turned on...

We got a little water when flying in heavy rain before the velcro but are hoping that the velcro solves that...

Its challenging but I think we've got it as good as possible. Very slight draft from back still but very manageable.

Good luck

You can just see the D-tube and foam strip in this photo...



This is how I did the cover...

Cabin heat

I put in a heat valve at the firewall which uses either hot air from the heater muff or air from within the cowl which is warm but not as much as heater.
It increases the volume of warm air but the best solution is the seat heaters I put in both seat bottom and backs, seldom use front one but they work beautifully.

I completely removed the heat box and muffs from the RV-8 and use heated vests instead. My firewall has zero insulation and my feet are fine in any condition (summer or winter). I rarely have to use the vest, and if I do it is just for a few minutes to get the pre heat going. My wife has the same vest as well as heated insoles which keep her nice and toasty.

In short, I traded several pounds of maintenance intensive junk hanging on the engine for an ounce or two of wire and power jacks and now have a completely satisfactory cabin environment for both occupants.