Cabin Heater Instructions

[tdldedcd]

Hi all,

Finally getting back to the build. I'm thinking of renaming it the sloth build. Does anyone have the installation instructions for the cabin heater? There are several different versions out out there. The original owner purchased the kit in 2013. Below are pictures of my heater core and some of the hardware. I appreciate any help and advice that you have.

Thanks,

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Todd

[DesertFox4]

Found a couple build photos.
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[Delta Whisky]

I did mine like DesertFox but happened to have some installation process pictures.

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I don't remember why I felt the spacing operation was needed - maybe as you do yours it will become clear. Or, someone else may be able to weigh in if it is even needed.

[AvDES LLC]

I tried playing that game with the computer fans as well and there it’s wasn’t enough heat come the really cold weather. I went with a ducted and shrouded option that I absolutely love. Cover the shroud inlet at the firewall much like Cessnas do with a small sliding piece of aluminum plate and you have a cable driven on/off for your heater and it consumes zero additional power and pulls heat out from under the cowl.

I have about 4 more of these shrouds cut (not bent) that I could get out to anyone that’s interested

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[tdldedcd]

You guys are great! Thanks for the quick replies. The pictures are extremely helpful. Gonna put in tomorrow!!

Todd

[pilot5173]

AvDES, this is exactly what I was thinking of doing. The computer fans just aren't cutting it. Do you have any pics of the firewall/engine side of this installation? ...and I'd definitely be interested in one of the shrouds!




...Cover the shroud inlet at the firewall much like Cessnas do with a small sliding piece of aluminum plate and you have a cable driven on/off for your heater and it consumes zero additional power and pulls heat out from under the cowl.

I have about 4 more of these shrouds cut (not bent) that I could get out to anyone that’s interested

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[AvDES LLC]

It appears I didnÂ’t take a photo after completing the hole in the firewall. IÂ’ll snag one tonight and post it. I didnÂ’t end up going with the sliding aluminum flap - I have a ball valve on my heater core that allows me to shut off coolant flow to the heater so the air coming through the tube kinda just keeps my toes cool in the summer haha. Ill try to get a few different angles of photos for you. Shoot me a private message to discuss the shroud if you are still in need.

[VictorV]

So you're using air from the engine compartment? Is that safe from a CO perspective?

[AvDES LLC]

https://qph.cf2.quoracdn.net/main-qimg-aafddadb38076b9bf3aa8ec4eab4af9d.webp

I would assume it is no different (if not slightly safer) than the standard means of heating your cabin when considering how the certified aircraft do it. As long as you have a decently maintained exhaust system that doesnt dump CO under the colwing instead of out of the pipe end it shouldnt be a worry. Couple that with the less than ideal "sealing" that the cabin of a KF has alongside the digital CO meter I fly with, im about as worried of a CO issue in this plane as I am with my 175.

[VictorV]

That makes sense. The diagram is helpful to see how it's done in certified aircraft. I am installing a CO detector as well.
I like the idea of not relying on electric fans.

Victor

[AvDES LLC]

Depending on the engine combination you go with coupled with the avionics you plan to install, you may see that you end up consuming quite a bit of the power output by the charging system - With that in mind and in an effort to minimize power consumption, this design was born. Since installation, ive placed about 80 hours on the place in the configuration shown with zero issues. With that said, im also under my cowling almost EVERY time I fly - so if something were loose or missing im rather confident it would be caught before it ended up becoming an issue that would impact flight safety.

Completely forgot to snag pictures last night of the setup - ill try to make that happen this evening.

[rv9ralph]

I think you are interpreting the "certified aircraft" diagram incorrectly.

Certified aircraft do not use engine compartment air to heat the cabin. The air is taken from outside the cowl, passes through a "heat muff" that surrounds the exhaust system to warm it, then it passes into the cabin. It is outside air that is heated.

If air is taken directly from the engine compartment, due to the circulation of air around a moving aircraft, CO may be sucked into the engine compartment.

Your method of heating the cabin would work, if you pull fresh air from the outside, front of the aircraft. Duct it through a heat muff surrounding your muffler, then routed into the cabin through the firewall.

Even with a CO detector, it is not wise to tempt the possibility of CO poisoning.

[AvDES LLC]

appreciate the input! Interpretation is spot on with yours. As you stated, the air is passed through a chamber that surrounds a muffler before entering your cabin. These mufflers often crack and as a result of that it is a requirement of the annual inspection to pull the shroud off from around the muffler and inspect for cracks. This is an almost “direct inject “ of CO into the cabin if a weld cracks.

consider the flow path of air through the cowl of a KF and you’d note that even if the muffler cracked, as a result of the cowling forcing inlet air from the nose, over the cylinder, then down the firewall and out the bottom, it would be safe to assume that even a crack in a stock rotax exhaust would still result in minimal CO input into the cabin with my design. Moreover, take into consideration “cabin air” on a 172. They pull that air through a port in the firewall that is DIRRECTLY behind the muffler on the co-pilot side in the older models. That intake point paired with the only opening for air out of the cowling being the ports, or the nose gear opening, flow is rather restricted.

I haven’t ran a CFD model to verify any of these assumptions but I’ll stick by them until presented with something to the contrary.

[avidflyer]

One thing to mention in this whole heater discussion. I have a thermobob thermostat on my Kitfox to keep coolant temps up in cold weather. There is a bypass line on the thermo bob, that is run through the heater core in my installation. When things warm up enough and the thermostat starts to open, I do loose some heat from the heater core. For my next Kitfox build, I have a small radiator with 1" fittings on it that I will use for the heater core. It will be plumbed in before the thermostat, so it will always get a good flow of hot coolant. JImChuk

[AvDES LLC]

As promised - photos of the install through the firewall. Don’t mind the wiring, the plane is under the knife right now and hope to be flying again in a few months. 313363133531337