How do airplane heaters work?

Question

rather how does a PA-38 Tomahawk's heater work?

Answer 1

It depends on the airplane.

Small airplanes, (singles) very often have a shroud around the exhause manifold, that gets warm air into the cabin. (if it's really cold out, the people in the back freeze.) Remember to close the cowl flaps if you have them.

Somewhat bigger aircraft usually have a combustion heater and blower, that burns fuel solely for heat. (generally found like this on light twins, as it is difficult to get warm air from engines to the cabin.

Turboprop airplanes will usually use bleed-air from the turbines to heat the cabin. The air is compressed to go through the turbine, they redirect a little of it to the cabin. The compression part of it makes the air hot. This air is also used to pressurize the cabin, but the warmth from the bleed-air combined with the need for heat usually finds a pretty good balance.

On large jet aircraft, they pressurize the airplanes more than turboprops, so to heat the airplane, they usually turn down the airconditioner. -- the airconditioners are always running to cool the hot bleed air to make in comfortable in the cabin.

Answer 2

Actually, on larger jet airplanes, the heat comes from the engines, and not a gas powered heater.  Basically, a jet engine does four things.  Suck, squeeze, bang, blow.  It sucks air in, compresses it, mixes it with fuel, burns it, and ejects it out the back of the engine.  As air is compressed, it gets super hot.  hundreds of degrees.  Air is tapped off of the engine's compressor stage, and routed through heat exchangers of some sort.  It is also used to pressurize the aircraft.  You may hear this air referred to as bleed air.

Answer 3

Peter nailed it...  I had the fuel type heater in the old original PA-31 (310) Navajo and if you missed turning off the heater on your before landing checklist, it would remind you on the next leg by not working. It had a circuit breaker or thermistor that if you left the heater running after landing, not enough air would pass over it and it would get TOO hot and pop the red button. You could only reach this button when on the ground because it was up in the nose on the right side.. and you had to open it up and press the reset button to get the heater going again... and after you froze your *** off a few times, you didn't skip over that part of the before landing checklist anymore.

Answer 4

Often on smaller airplanes like the Tomahawk they have a shroud around the exhaust coming off the engine that takes the warm air and funnels it into the cabin thru a scat tube.  These have to be inspected every year as part of the annual inspection to make sure that there is no holes that would send Carbon monoxide into the cabin.  On larger airplanes they can actually have a little electric or gas driven heater - these two are inspected to make sure that they are not leaking carbon monoxide into the cabin thru the heating ducts.