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It's cold, Mooneys heaters


Danb

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Went flying today it was a balmy 10*f when I departed and I tooled around at 3000 feet, I pulled the tab on the heater but basically had nothing but cool air,  after 45 minutes to an hour not much better. It seemed to me to work a little better last year, am I imagining I had heat before, at what temp do you all get some heat relief.

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I had very weak heating performance with my Eagle.

Quick fix: I plugged the cold air inlet for the heating system. with a foam plug  It's the inlet on the co-pilot site of the engine cowling.

Permanent fix: The separator in the  hot/cold air mixer had 3 or 4 holes drilled in it. That kept cold air flowing.Taping these holes with aluminum tape makes a big difference. The mixer is above the rudder paddles on the co-pilot site. 

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To increase heat output...

1) increase FF.

2) increase EGTs.

3) decrease outside air being mixed in.

4) Usual TC / TIT precautions still apply...

 

M20C...

At 10,000’ in an NA plane, There won't be enough heat to overcome the cold air entering the cabin from the various leaks...

 

M20R...

Better seals, more FF, lots of heat to spread around.

 

Expect with the M20M That There is plenty of FF available to get good heat, Operating at normal TITs is good for generating heat.

 

Cold air is good for cylinder cooling. But, also has the ability to cool the heat muff with that.

 

PP thoughts only, not a M20M pilot....

Best regards,

-a-

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9 hours ago, Danb said:

Went flying today it was a balmy 10*f when I departed and I tooled around at 3000 feet, I pulled the tab on the heater but basically had nothing but cool air,  after 45 minutes to an hour not much better. It seemed to me to work a little better last year, am I imagining I had heat before, at what temp do you all get some heat relief.

I get warm air during taxiing.  Did you have the cowl flaps open?  that will send the warm air from the exhaust muff out the bottom.  On cold days, I'll start and taxi with the cowl flaps closed to get the heater, and, more importantly, the defroster going.  As long as you watch your CHT's.  In 40degF weather, my CHT's stay around 280degF taxiing around with the cowl flaps open.  I figure if they go higher, I'll just open them and run the engine a little longer.

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I never had a problem with insufficient heat when I lived along the Ohio River. My coldest takeoff was 8°F and although my wife chose to stay home, the cabin was toasty and warm. Most of my IFR training was in the winter, and even sjth snow in the ground, the CFII and I often took off our jackets not long after takeoff.

But then again, my cowl flaps are fixed and I don't have a turbo.

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Closing the cowl flaps from trail to closed boosts heat by like double or triple in a “J” model. I the winter cooling isn’t a issue, at least for me so I get those blasted things shut ASAP after take off and that’s if I opened them at all if it’s really cold.


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10 hours ago, N131MA said:

I had very weak heating performance with my Eagle.

Quick fix: I plugged the cold air inlet for the heating system. with a foam plug  It's the inlet on the co-pilot site of the engine cowling.

Permanent fix: The separator in the  hot/cold air mixer had 3 or 4 holes drilled in it. That kept cold air flowing.Taping these holes with aluminum tape makes a big difference. The mixer is above the rudder paddles on the co-pilot site. 

These "fixes" will indeed work. just make sure you have a carbon monoxide indicator in the plane to alert you if CO is building up. The continuous outside air flow was intended to keep the CO levels down.

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If the air supply that flows over the exhaust manifold is not sealed up good that could contribute to loss of heat. I had this challenge on my F and found the tube from the heat muff to the fire wall was sad and needed replacing due to leaks. 

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My aircraft has two knobs, a Cabin Vent knob and a Heater knob.  They both supply air into the cabin through the same slot, the heater slot.  Be sure when you want full heat, that the Cabin Vent knob is all the way in (closed, or off) or you will be mixing cold air into the heated air stream.  I am not saying there are not times when the heater could use some help, but it does not help if the Cabin Vent is open even a little bit.

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The heat system in turbocharged Mooney’s is not up to the task considering the performance altitudes the plane were designed to operate.

Item 1 in the drawing is the “heat exchanger” in a Bravo. Combined with the 4 holes in the cold air valve it’s an impossible task.  The normally aspirated models do better.

Clarence

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Clarence usually brags about his eight cylinder Comanche, since he forgot to do that in this thread and since I've had a few winter time rides in it, I can tell you that it has no trouble pumping out heat.

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