Carb heaters, carburetor heater for Rotax 582 aircraft engine, carb heat for Rotax 912 aircraft engine

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Rotax carb heat 1

A simple system for supplying  carb heat to a Rotax two stroke aircraft engine courtesy of: 

Otto Frohlich from Germany sent in these two photos. Since Otto n I can only communicate thru a computer translation program, naturally our exchange of words is somewhat limited. Rotax 582 carb heat.This being the case, I am commenting on what I can surmise from the photos.  

Otto added a carburetor heat system to his CH-7 Angel. Above you can see how his system recovers heat/warm air from the 582's exhaust system. Below you see how it is added to the air cleaner.

What is not obvious in the photos is if  the heated air is permanently added or if there is some way to stop the heated and un filtered flow from entering the air filter?
Also it looks like Otto has a temperature or perhaps a humidity probe mounted in the air cleaner. I would suspect it is a temp probe.....
I was stationed in Germany during my days in the US Army (Fligerhorst near Frankfurt AM, 1970/71) I can remember many cold and damp days when carb heat would be a must.


A simple way of redirecting the air would be to install a "dryer duct control. These are used in cloths dryers for directly air outside or inside.

The unit used to capture the air is available from most ultralight aircraft supply depots. The Leaf catalogue lists one used for heating the cabin (which I do NOT recommend) but for carb heat as shown above should work - as long as you can open and close the valve when needed.


Rotax 912 carb heater

For 912 ULS engines, in operation the carb heater adds a small amount of heat to the carb body at its downstream end in order to keep the temp of the body above freezing point. The intention is that any ice formed will not adhere to the carb throat.

Because the heater block is adjacent to the throttle spindle, some heat is also transferred through the spindle to the butterfly, to prevent a thick build up of ice on the butterfly, which with the type of carb used, can be a cause of rough running and possible engine failure.

Because there is no significant heating of the intake air when hot coolant is circulating through the carb heater blocks, there will be a negligible loss of full engine power.

A suitable tap and additional tubing (so that the pipe work can be extended to fit the tap in the cockpit) is available as an optional extra. An optional digital temperature gauge is available,  this monitors the temp of one of the heater blocks closest to the carb throttle spindle.

Extensive testing of the system has been carried out during an English winter, and it has been demonstrated that the system will prevent the formation of ice, and will also clear an ice build-up if the optional tap is turned on after the engine begins to run roughly due to ice formation.

The system has not been tested under all possible conditions that may prevail, therefore its effectiveness cannot be guaranteed in all circumstances. Aircraft equipped with this device should never be flown in circumstances where a successful 'no power' landing cannot be made in the event of engine failure.

Rotax 912 carburetor heater - kit does two carbs. $295.00 U.S.  
Optional gauge $45.00 U.S.