Tired of the cold - building a pre-heater

[MooneyBob]

So I decide to build the preheater for my M20J. Here is my idea. Table top 1500 Watts heater attached to bathroom ceiling fan. I will leave a small gap between them to prevent over heating and plastic melting. Everything will be installed on the heat resisting piece of material. See attached picture.

I will use the duct work and flexi duct to run the warm air to the cowl flaps opening. I will test it and measure the temperature of the output to make sure it is not too hot. I don't want to go over 100dF. I will place the thermostat into the oil check door opening on the top of the engine as a security precaution and I will set it around 100dF. I will use the timer to manually turn it on and set the timer for few hours just in case I can't make it back to the hangar for some reason. If it is going to work I will connect it to the switch box or any other remotely controlled switching devices.

 

Any advice or reason for not doing that? Any fire hazard or any other danger involved?

 

Thanks

[Marauder]

Or you could have just called me an I would have given you my homemade propane setup that I no longer use because I installed a Reiff...

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[Cruiser]

there are lots of these around, some are very sophisticated and inventive. Just position the unit outside the airplane perimeter not under it in case something happens and it melts down you don't catch the plane on fire. 

These type of heaters are transferring heat by convection which raises the exterior temperature of the engine/compartment. The engine must then transfer the heat by conduction to the interior pieces/parts. This can take a lot longer, check the temp of the oil on the dip stick to get an idea of what the interior temp is.

[MooneyBob]

Thanks guys.

Eventually I will go with something more sophisticated but I really want to fly this weekend and it is still freezing outside.

[AndyFromCB]

I leave my Bravo in the hangar with a little space heater in back, I mean little, the smallest one I could find. Never had any issues and the cabin is nice and toasty 80 or so when I get in. I bolted it to a metal plate about the size of the baggage door so there is no possibility of it tipping.

[TWinter]

Here is how I did it. The plane has a regular engine pre-heat plug, but in addition we hooked up a portable thermostat controlled heater and vented it into the plane using dryer duct. You could also put in a T in-line with the duct and have it funnel both into the plane and also in the cowl flap/engine compartment. I have it plugged into my switch-box. Dial it up and good to go. Thermostat makes it great because it gets to a decent temp and cuts on and off automatic for the cabin, but does not turn the engine pre-heat off.

[TTaylor]

Should be fine, but why not just use a Milk House Heater with the fan built in?

[larryb]

I bought a Reiff and a cell switch. Not because these home-made efforts don't work. I did it for the convenience:

 

1)  No setup and tear down. Just plug in the extension cord.

2)  Turn on via Txt msg the night before a flight. Don't have to leave it on all the time and waste power.

3)  Can leave it on with the plane un-attended.

4)  I can use it away from home, and all I need to carry is an extension cord.

 

Now, on to your idea. The thing I don't like about it is the bathroom fan. The air temp out of the heater is a lot higher than the air temp a bathroom fan normally sees. I doubt it will last long in this application. If I went this route, I'd start with a metal milkhouse heater and duct it's output. And only run it on it's half-power setting.

 

Or you could use 200w of incandescent trouble lights under the cowl with a blanket and cowl plugs.

 

Larry

[MooneyBob]

That's why we use the forums. All great ideas will eventually come out.

Thanks

[triple8s]

I made a heater today in minutes. I used two ceramic 120VAC heaters and a 6 foot long piece of 8 in aluminum flex duct from home depot. I had some foil backed insulation already and after bending the fex duct to shape I wanted I wrapped and taped them up with the insulation. I have a Tanis engine heating system so it takes just a few minutes to heat everything up. I direct the heat up from below by sliding the flex ducts over the tail pipes and the heat blows up and through the engine exiting the cowl air intakes. I pull the CB on electric TC, avionics fans, and turn off my radios at their knobs so i can power up the JPI 730 once in a awhile to get a temp reading on the CHT and oil temp. after reading about engine oil coolers bursting I have become paranoid about making sure EVERYTHING is up to temp before start up. I even have a winter plate to slide into the holder infront of the upper half of the oil cooler.

 

http://www.oilcoolers.com/article_oil_cooler_woes.asp

 

This will get your attention.....

[Hector]

Heater $19 at Walt Mart. The other tubing from Home Depot. Works great.

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