Heating/ Pre-heating

[mikey757]

I have a Reiff engine pre-heater and a cabin heater from aircraftheaters.com.  I have 120v electric at my hangar to plug them both in. Is there any reason that I can't leave them plugged in continuously if I only fly every few weeks or so? I have seen the adds from Switcheon but figure it might be better to just leave them on all winter. Thoughts?

[Fly Boomer]

I think that temperature rising and falling is the problem -- causes condensation.

[jaylw314]

IIRC the concerns about leaving engine heaters is that they usually heat the oil more than the rest of the engine.  Any moisture in the oil then condenses on the colder parts of the engine, so there can be a corrosion risk.  In theory, heaters that heat up the top part of the motor too should mitigate this, but it's hard to imagine heating up every single part of the motor to avoid condensation

[Fly Boomer]

Just now, jaylw314 said:

IIRC the concerns about leaving engine heaters is that they usually heat the oil more than the rest of the engine.  Any moisture in the oil then condenses on the colder parts of the engine, so there can be a corrosion risk.  In theory, heaters that heat up the top part of the motor too should mitigate this, but it's hard to imagine heating up every single part of the motor to avoid condensation

I have Tanis, but what happens in practice is that, while they have "low heat" and "high heat" versions, even with the "low heat" version, eventually the entire engine is warm.  Now, if you have only an over-powered heater on the oil pan, your concerns are real.

[jaylw314]

5 minutes ago, Fly Boomer said:

I have Tanis, but what happens in practice is that, while they have "low heat" and "high heat" versions, even with the "low heat" version, eventually the entire engine is warm.  Now, if you have only an over-powered heater on the oil pan, your concerns are real.

The top becomes warm, yes, but it's always cooler than the oil pan since heat is always going in there and out the top.  If there's enough moisture inside that the dew point of the humid air inside rises above the temp of the top, you'll get condensation, even if the top is warmer than the outside air.

I suppose if you had one of those dehumidifers that blows dry warm air in through the breather, that would be the ideal for constant heating

[larryb]

A few years ago I built a device to measure and graph humidity in the engine to help me decide these questions. I found that a warmer engine has lower RH. This makes sense because the warmer the air holds more water vapor. Moisture in the air is NOT moisture sitting on the metal. In other words, that moisture is not available for corrosion. Only moisture on the metal surfaces is available for corrosion. 

 

For myself, I have a Reiff with a thermostatic control and a quilt over the cowl. I use the thermostatic control to keep the engine compartment at an even 90 degrees F all the time. I keep the oil filler cap open to allow water vapor to escape. With the quilt, the whole engine compartment maintains a pretty even temperature eliminating the concern about moisture driven out of the oil condensing on cooler engine parts. My Reiff is the version with 100 W bands on each cylinder and 100 W on the oil pan. The kit came with 2 100 W elements for the oil, but I only installed one.

 

Larry

[Ragsf15e]

You’ll find unlimited opinions.  If it’s really cold, corrosion is stopped/slowed even if water is on metal.  There’s some good charts for this on another thread.  If you can keep the whole engine warm, that likely works fine too.

I let mine cool down after flying and use a space heater attached to a dryer vent hose to heat into the cowl flaps the evening before I fly.  I use a gsm switch like switcheon but it’s a different kind.  Name escapes me right now.  European.  Sorry.

Either way, you’ll likely be fine.