$35 Pre-heater

[dcrogers11]

I know there has been some discussion on the subject of pre-heating so here's what I built for my hangared airplane. It may not work for everyone, but this setup has worked well for me in Texas where we're not hammered like the guys up north. I used it today and here are the findings-

Ambient hangar temp- 31 degrees

Time heater was used-4.5 hours

Lasar gun temp of crankcase-33 degrees

Lasar gun temp of crankcase after 4.5 hours-78 degrees

1300/1500w heater from Home Depot-$19.95

Flexable vent hose-$14.00

Scrap thin plywood- $0

[carusoam]

DC,

Nice engineering data/details?

I really like the visual cues for parts left in place.

Distractions can really ruin your day.

Best regards,

-a-

[aerobat95]

I would be definately interested in building something like this.....how did you attach the vent hose to the heater?

[DonMuncy]

I like your system, especially the price.

From your post, I presume you haven't used it for an extended period of time. I worry a little about a unit which is (apparently) designed to be freestanding, being used in what amounts to a "forced air" system. Does the fan in yours appear to be able move enough air through to keep from overheating or overloading its fan. Maybe since you only use it when the temperature is quite low, this is no problem.

[rocketman]

I think by fitting the inlet through the cowl flap and letting the warm air rise through the cowling, heat would be better distributed. A sleeping blanket, cowl inlet covers, and a cell switch or something that allows you to call up your heater two hours in advance of your arrival makes the perfect engine warmer.

[dcrogers11]

I was concerned about overheating issues as well so the first time I used it, I stayed with it and checked the surface temps of all the surfaces involved with my infared gun. With cold ambient temps acting to cool the surfaces including the heating coils, no temperature exceeded 95 degrees. The space heater has a 1300w and a 1500w setting. I use the 1300w to prevent temps getting too hot although I don't think they would on the 1500w setting. The 4" hose does allow for suffecient flow up to the plane so it doesn't seem to affect the small heater.

Ray-After checking temps on the front surface of the space heater, I just used some wire ties looped through small holes punched in the vent hose and looped them around the 2 gaurds on the front of the heater. These are the two gaurds that are there to prevent the heater surface getting too close to another object. I guess that I'm using them to do exactly what they were meant not to do. I was careful though to check on the heat build up and it was never a problem. My hangar is attached to my house so I don't wont to loose my plane and my house.

[Alan Fox]

Outstanding!!!

[Riq]

Very nice. I like the plywood enclose.

My fbo went from 15 to 25 to 50$ a preheat in a matter of a month 2 yrs ago, so ive been trying everything.

I went with a propane tube heater and scat for fast heating out the back of my expedition straight to the cylinder. ~30minutes@10f

Tanis with a ceramic heater in the cab controlled by a 35$ cellphone activated switch. ~3-4hrs@10f

Today im going to make the milk house heater as you have, yet try to run the intake of it to the other cylinder bank circulating the flow. Ill test for overheat in my garage before use.

[Seth]

_{I built one just like this for my older F model. My Missile has a plug in Tannis heater. I've considered using the old system to heat up the cabin if it were a really cold day (have the air under the footwell to warm up the avionics, but I have never used it that way.}

_{It's just sitting on a shelf in my hanger at this time.}

_{I did use it a handful of times with my F and it seemed to work well even though I never actually tested it with metrics and temperature guages. I would let it run on cold days for 30 minutes (which probably did very little) to about three hours before starting the airplane. I did not trust the unit to be left alone, so I'd have it set up, but only turn it on upon my arrival to the airport. I would leave my cowl plugs in and have the vent hose enter through the lower cowl flaps. so the air would rise into the engine compartment. It did get nice a toasty in there and the engine block was warm to the touch after a few hours. The engine started much easier in the cooler winter days when I used my pre-heat option. I didn't often fly below 40 degrees back then and only used this device once I had a hanger. When I had the airplane tied down outside or on the ramp, I'd ask the FBO for a pre-heat which was a hot air system blown into the cowling for about 15 minutes (very hot air).}

_{I'm much more happy with the plug in system on my Missile today. The small home made heater option however worked well and I'm sure would work in the current aircraft if for some reason the tannis system stopped working.}

_{It too cost me between $25 and $35 to create. Be careful if you use that dryer ducting as it gets hot to the touch - if I had to use it again I'd get scat tubing or some sort of insulated duct.}

_-Seth

[Dale Logsdon]

100W light bulb does wonders

[N601RX]

You should be able to greatly reduce the warm up time by placing the heater on the top of the cowling and rigging up a return line through the oil filler door. Perhaps just put some foam weatherstripping on the back of the heater and lay it facing up over oil fill opening. This will allow the air to recirculate and get warmer. You can also add a dipstick heater for $20 or so.

[Awful_Charlie]

  On 12/27/2012 at 11:32 PM, Dale Logsdon said:

100W light bulb does wonders

I'm a bit wary of that. If we say an engine and accessories under the cowl is 500lbs, and is half steel (0.11BTU per lb per degF) and half ally (0.22BTU per lb per degF), then a 100W heater is going to give you about a 4degF rise per hour, assuming all of the heat goes into the engine.

If you want to make a 30degF rise in an hour, you need at least 750W or 2500BTUs

[Dale Logsdon]

Cover your air intake, cover your cowling with an old blanket, insert and old style 100W drop light with a metal light bulb guard into cowl flap opening and close cowl flaps.

This is not for a quick preheat, but will maintain a nice warm engine and can be left pluged in all winter or just when a cold snap is forcast.

Put a thermometer inside your cowling, plug it in and come back in a couple of days and check it , you will be surprised

[Riq]

Its been -10 here all week, im not sure a 100w bulb would do much for me.

[carusoam]

Riq,

Where are you?

Best regards,

-a-

[KSMooniac]

My solution uses a small space heater with a squirrel cage fan and adapted duct work to take the rectangular outlet (maybe 10" x 4") to a 4" round duct. I place the output inside one cowl flap, and made a similar rig for return air from the other cowl flap to the heater intake. I leave my cowl plugs in and get +20-30 dF in about an hour of use. I use a smaller heater in the cabin as well to get the gyros warmed up a bit too.

[RJBrown]

Riq appears to be in Minot North Dakota. My father in law flew B-52s out of there about 1968-1970. My wife tells of ice skating to and from school in the dark. Too cold there for me, even Denver is getting to cold for my thinning blood, 9* this morning when I sat down at work. Those of you with a hangar and electricity count yourselves fortunate. The shelter I park under has none. I will run out to the airport tonight to leave my generator running for the Tanis. That and the propane heat will get us off to Salt Lake in the morning.

[Riq]

You are correct, I'm in Minot, ND. "ice skating to school in the dark" lol, that's good stuff It's a blistering 9 now, so I might go out snowmobiling.

[RJBrown]

Sunshine and a balmy 29 here in Englewood. I shudder every time I hear her "cold" stories. Phoenix is cold this week, up to "only" 54 right now.

[N201MKTurbo]

I think it is freezing cold here in Phoenix, it was 34 this morning and the windows on my truck were iced up. I don't think it will even get up to 60 today....

[Scott Aviation]

This is what I built out of a ceramic heater and some stainless steel. Cheap under $45. Plane is normally hangar end but I was visiting family over New Years and it was -6'C so 7am turned the heater on outside came back 2 hours later to a warm cowling plane fired up first blade rotation. I just stuff a couple of rags around the edges to keep the heat in. Scat hose is nice and short for storage and less heat loss. Overall I'm really impressed after 1 use.