[Paul Kortopates]

Dustin, are you opening the cabin air along with the cabin heat? Think of the cabin heat as heating the cabin air, without the air there isn’t any air coming through. I mention this because with both it gets real hot real quick.

[Kevin Wittrock]

My wife and I flew back from the Phoenix area yesterday. It was -15C at 7000 and we were both cold. All the vents were closed and the heat pulled out all the way. My wife likes to ride in the back and she was wrapped up in two blankets (and complaining). This is a M20R. My previous J model had a far better heating system. It’s an Ovation issue I’m afraid.

[Dustin Kurath]

Paul, that’s an excellent question. I can tell the heat is coming through, but there is way too much leakage. The heat comes through from a vent that opens inside the engine compartment when I pull the heat open to allow air to pass through the heading duct and past the exhaust manifold to be heated, so heat comes in even with outside air vents on the fuselage plugged. Before the heat enters the cabin, it mixes with outside air through a baffle in an airbox under the instrument panel by the blower fan. The outside air is supplied by the right NACA vent on the forward fuselage and the baffle under the instrument panel that opens and closes outside air has holes in it, so it cannot be completely closed severely reducing the amount of heat that can be delivered. The easy solution to this is to plug the right NACA vent with a microfiber cloth, dramatically reducing the cold air flowing into the cabin. There is a left side NACA vent that supplies outside air to vents near the rudder pedals, and a vent right in front of the tail that supplies air to overhead vents. All of these leak cold air, even when closed, however, the worst offender for rear seat passengers is cold air leakage from the fuel selector, trim wheel, and emergency gear extension assembly. I made small see through plexiglass covers that fit over the emergency gear extension and fuel selector that help tremendously and do not interfere with their operation, but I would like if Mooney could come up with something, at least in a future design, to seal up the whole assembly from underneath eliminating the problem, and possibly offer shutters or factory plugs for the external air vents for extreme cold weather operation. A brush seal on the trim wheel would help alot too.

 

[Mooney Technical Support]

I will pass this information on to Engineering –

Just an FYI – Be Cautious when sealing up areas like the NACA ducts and other specific places, is that spent exhaust gasses may create high concentration carbon monoxide (CO) in the cabin due to lack of fresh air mix.

Best Regards, Frank

[Author]

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