Cabin Heater Instructions

[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. 5FD48508-2BEC-4264-85D2-323630C2C752.jpgC2182D91-6735-411A-BC40-0C372508089B.jpg4EB13A46-DDE5-4A25-A2D9-AC5F5FF18992.jpg