engine pre-heater

It has been cold here in Oregon lately. I was able to go flying for a couple of hours last Sunday, but before I went I wanted to warm up the engine a little.
When I got to the hangar the engine monitor said that the oil was 37 degrees. I think that it was more like 32 in the hangar.
I took the top cowl off and place a small (1500 watt) heater on top pointing down at the case. I then covered it with some firewall blanket tucked inside the baffle.
After 1 hour the engine monitor claimed 50 degrees and I felt that this was ok to go with. The plane is not hard to start, it is just that I don't want extra wear on my engine.

Now the question, has anyone made a pre-heater from a small heater (cheap) before?
I don't want to have to remove the cowl. I as think along the lines of a box with one or two of the orange header duct line going to the cowl inlet and then sealing the rest of the opening with something.

I don't want to reinvent the wheel, so if someone has a suggestion or plans I could use, great.

Kent

I took an electric "milk house heater" (approx 14" x 12" x 8") some 6" household ducting, a couple of 90 degree elbows, and pop riveted it togeather and push the heat up through the bottom of the coweling between the exhaust pipes. I added some 1" alum angle to the bottom for stability. I took some 3" foam and cut blanks for the holes in the front coweling, and I throw a towel over the coweling for insulation.

I leave it on 750 watts 24/7 under 30F and the engine temp is always 60-70F. Make sure your ducks don't catch any oil dripping out of the breather tube.

I've always wanted to make a skirt (no comments from the peanut gallery) that goes around the engine and draped to the floor to hold the heat in. Even a sheet would make a huge difference.

I tell you what, they are a little pricey, but the Tanis engine pre-heaters are worth it. I had the one that has probes for each cylinder, and a pad for the oil pan on my Cherokee 180, and it was probably the best $350 (three years ago) I spent for winter weather ops. Just go out the night before a trip, plug it in, and it's ready to go without hesitation the next day.

DO NOT LEAVE THEM PLUGGED IN ALL THE TIME!! That will trash your oil...

I plan to put one on my engine. They work!

Regarding engine heaters:

DO NOT LEAVE THEM PLUGGED IN ALL THE TIME!! That will trash your oil...

Click to expand...

Many of us that use engine heaters disagree with that opinion.

I have a small ceramic heater that has a shroud made of aluminum terminating in a 3" duct pipe. Then 3" flexible dryer vent tubing comes off that which I stuff in the cowl exit between the exhaust pipes.

I have this plugged into a thermostat that is normally used for heat tape that is used to keep water pipes from freezing. I stuff this into the oil door in the cowl with the power line from the wall socket going into the thermostat, and then a chord from the thermostat coming back out the oil door and down to the heater which sits on the floor under the airplane. Then I throw 3 blankets over the cowl with one of them tucked into the cowl inlets.

I keep this plugged in 24/7 and the heater tape thermostat keeps the entire inside of the cowl at between 38-50 degrees. That may not seem like much to you fellers from Texas, but up here in Wisconsin, in the winter, that is darn right balmy! My engine turns over just great and starts quite easily. Also keeps my battery happy. The heater kicks on maybe 2-3 times/hour with the temps in the 20's, with each cycle lasting maybe 1 minute. Hardly runs at all.

In the really cold weather, I also put another ceramic heater inside the cockpit on the floor to heat up the instrument panel an hour or so before I fly. Otherwise, things like my Dynon and Lowrance airmap 1000 are REAL sluggish to get motivated.

Engine Pre-heater

I use an EZ Heat Model 441 that's glued to bottom of oil sump on my RV6A with an O360A. It works on a 110 volt male plug accessed from the oil door. Works like a champ. Maker sez OK to leave on all the time. I've left it on weeks at a time. Anybody else have any experience with these? Manny E. El Paso

Sam Buchanan said:

Regarding engine heaters:



Many of us that use engine heaters disagree with that opinion.

Click to expand...

I figured somebody would disagree with that...

I have done exactly what "geico266" did - milkhouse heater with Al dryer duct attached to the front - total cost about 25$ from Menards.

Shove the duct into the bottom of the cowl, cover the top with a blanket, and you're all set. Keeps the battery and everything warm.

I have a Reiff system on the skyhawk and I love it, it works great, but is far more expensive.

Thomas

Small Heater

Hi Guys
This is an interesting thread for me. One of the problems I encounter with my Champ was starting in cold weather. I solved that problem with a $25.00 100w silicone heating pad from my local NAPA aviation supply store. I had it plugged in 24/7 with on harmful affects to the oil. I have installed the same type of pad on my Lycoming oil sump it is plugged in 24/7. The mornings here have been between 10 & 20 degs F my engine starts quickly and the oil pressure comes up with out hesitation. I believe having a small wattage heating pad on 24/7 heat soaks the case, cylinder bases, crank, cam and all the other core components. The oil is at 60 degs F after engine start and would think the rest of the engine is close to that temperature. IMHO

Reiff

I have the Reiff system on my oil sump and it'll get the oil to 100 degrees overnight in 30 degree weather. I have a friend with a Cirrus 22 that we just installed one on.........loves it.
http://www.reiffpreheat.com/

Regards,

timer

I, too, used the milk house heater/duct setup but with the addition of a household timer I would begin heating an hour or so before wheels-up time while I'm still at home reading the morning paper, er, Doug's site.
Steve

Engine Preheater

I'm using the sump heater sold by Vans. It works well. If I know that I'm going flying in the morning I connect it to a timer so that it will kick on a couple of hours before engine start. Wrap the cowling and prop in blankets. It is suprising how much heat loss is conducted through the prop.

I also use a ceramic heater in the cabin to warm up those batteries, radios, & gyros which seem to object to the colder temps.

Joe Blank
RV-6
N6810B

Heaters

We've run several Lycomings with Tanis heaters left on continuously, even in the summer in Wis. Thought was to minimize condensation in the engine. Our engines have started easily and went over 2000 hours without any evidence of corrosion or undue wear (one PA24-260B and a PA32R Lance). Seems to work for us. When away from home we take a long extension cord and sometimes can find a plug. Bill

Wovlerine heater pads

With a FF sump there is very little room to get a silicone pad heater on the parts that the oil is contained in.

Do web search on "Wolverine engine heaters" I put a 50W heater pad on each side on he ears of the sump and leave then plugged in all the time.

I made a cowl plug for each inlet.

This arrangement seems to raise the CHTs by 35degF. I leave them plugged in all the time. Cost was about $60 I think.

Frank 7a under IFR torture...I mean training!

There are definitely 2 schools of thought on leaving the preheater on all the time, and people on other aviation boards get pretty passionate about it.

My thought is that I leave the Reiff plugged in all the time, with a heavy blanket on the engine so the temps under the cowl are 80-90F and constant. How is this different than your typical summer day in Indiana? Humidity is likely lower in the winter. I fly frequently enough (at least once a week) that it really isn't an issue.
I think the real problem is cycling - if you plug it in and don't fly, then unplug it, etc. I also can see the argument if you just have a sump heater and don't heat the top end, then condensation from the moisture in the oil could form on the top.

My .02 ... take it FWIW.

Thomas

Well, time to pitch in. I was in the same temps as Thomas above, but have only a sump heater by reiff. Leave it plugged in all winter long ( it has a thermostat embedded) Anyway, after many a year doing this, time comes when I had to change my mags (prophylactic) and guess what? I was expecting a lot of corrosion from condensation on the mags teeth. When I removed it off the case (rememember for those who dont know that it sits high) there was ABSOLUTELY no signs of rust/corrosion. Nada.
I have since decided that a good temp contolled sump heater like Reiff with a thermostat embedded is just as good and one can let it be plugged in until you fly.

Regarding off field preheat:
I have a MSR (mountain saftey research, google it) XGK multi fuel stove which burns 100LL great in a small satchet always in my plane. I made a little shroud for it with drier vent alumin stuff that will let you poke it into the cowl. You will not believe the performance of this little creature. With the cowl plus on and a blanket over the cowl, even parked outside on snow, it will get it to in about 15 min.
Now, Northern companion sells a basically similar contraption based on the XGK for a ... $. Fix it yourself.
I even took it to Afgahanistan when I was deployed in combat. Works great up to an altitude of 12K, weighs 9oz and will burn anything that you can throw at it. Sounds like a jet engine.
No I do not work for them, although I think I ought to.

Well, time to pitch in. I was in the same temps as Thomas above, but have only a sump heater by reiff. Leave it plugged in all winter long ( it has a thermostat embedded) Anyway, after many a year doing this, time comes when I had to change my mags (prophylactic) and guess what? I was expecting a lot of corrosion from condensation on the mags teeth. When I removed it off the case (rememember for those who dont know that it sits high) there was ABSOLUTELY no signs of rust/corrosion. Nada.
I have since decided that a good temp contolled sump heater like Reiff with a thermostat embedded is just as good and one can let it be plugged in until you fly.

Click to expand...

Same here. After using a sump heater 24/7 for six winters I have seen no evidence of engine corrosion or oil degradation. More details here about my experiences with and rational for a sump heater:

http://www.thervjournal.com/cold.html

It has been my observation that some of the loudest voices criticizing heaters are among those who have never used them......

Like Sam, my engine has not understood that it has been cold the last 6 winters. I keep the under cowl temperature thermostatically controlled to about 70F continuously. The inlet and outlets are blocked with foam rubber, and the whole cowl is blanketed. I have a Reiff sump heater as well as cylinder band heaters. This winter I put a hobbs-like timer on the system to see what its duty cycle is in a hangar heated to 45F, and it has run about 30% of the time. Since the heaters are around 300 watts, the average wattage in my case is about 100 watts.

If an oil company has data to show that keeping their oil at 70F is problematic, I'd perhaps switch oil brands. Perhaps keeping it at 130F is problematic, but even then I would like to see the data.

Keeping the entire under cowl thermostatically and uniformly heated simply will not be a problem if the temperature is reasonable, say less than 100F.

As has already been written, I believe the potential issue is when heating the oil only, but not allowing the rest of the engine to normalize to the same temperature. This situation would be the case with an airplane sitting outside or in a cold hangar, with no blocking of the inlets and outlets, and no insulation on the cowl. In that case, water will be driven from the oil to the cooler cylinders and other important parts.

My cheap but very effective preheater

What I and my hanger mate with an RV-8 do is insert two 1600 watt hair dryers into the outlet tunnel on the bottom of the cowling. We use spring loaded plastic clamps to secure. The hair dryers put out much higher air volume than ceramic heaters, at higher heat values than most heaters. Also suffer no heat losses do to duct work. I've been doing this for years. Would reccomend you give it a try. LOGAN

cjensen said:

I tell you what, they are a little pricey, but the Tanis engine pre-heaters are worth it. I had the one that has probes for each cylinder, and a pad for the oil pan on my Cherokee 180, and it was probably the best $350 (three years ago) I spent for winter weather ops. Just go out the night before a trip, plug it in, and it's ready to go without hesitation the next day.

DO NOT LEAVE THEM PLUGGED IN ALL THE TIME!! That will trash your oil...

I plan to put one on my engine. They work!

Click to expand...

A Tanis system will not trash your oil.

Dayton Murdock said:

Hi Guys
This is an interesting thread for me. One of the problems I encounter with my Champ was starting in cold weather. I solved that problem with a $25.00 100w silicone heating pad from my local NAPA aviation supply store. I had it plugged in 24/7 with on harmful affects to the oil. I have installed the same type of pad on my Lycoming oil sump it is plugged in 24/7. The mornings here have been between 10 & 20 degs F my engine starts quickly and the oil pressure comes up with out hesitation. I believe having a small wattage heating pad on 24/7 heat soaks the case, cylinder bases, crank, cam and all the other core components. The oil is at 60 degs F after engine start and would think the rest of the engine is close to that temperature. IMHO

Click to expand...

I assume you are aware that a non-FAA approved heater is a major alteration requiring a 337? An FAA-PMA'd heater is a minor alteration requiring only an engine logbook entry. Installing a heater without one or the other would not be a legal installation.

Heating Pad

Hi Bob
Thank you for your concern with the legality of my aircraft. I called my local FSDO and ask if my heating pad required a 337. I was informed that a experimental aircraft only requires a log book entry when a minor change is made.

Corrosion is an electrolitic reation that requires an electrolyte (water) and is actually accelerated by increasing temperature. The problem in cold weather is that we need heat to increase the viscosity of the oil and also to minimize metal tolerance issues due to thermal contraction. I spoke with a Lycoming rep at the recent Michigan Aviation Maint Conference, and they are are very negative about using constant heat during cold storage.

My own take on the issue from a metallurgical standpoint is that while constant heat in a cold atmosphere is not desirable, it should not be a problem if the aircraft is operated on a frequent, regular basis. Outside of flight schools, this is rarely the case. At the same time, there are very sound reasons for the engine manufacturers to recommend pre-heat below 40F. While the most efficient systems seem to be full top/bottom systems supplied by Reiff and others, I have found a sump heater left on overnight (and supplemented by a cowl blanket and intake plugs) has been able to uniformly heat the entire engine during even the coldest Michigan winters. Problem with a brief, high BTU pre-heat is that while the oil may reach acceptable viscosity, the metal to metal engine tolerances may still be a problem, or vice versa.

Dayton Murdock said:

Hi Bob
Thank you for your concern with the legality of my aircraft. I called my local FSDO and ask if my heating pad required a 337. I was informed that a experimental aircraft only requires a log book entry when a minor change is made.

Click to expand...

You said it's a Champ... is that Experimental?

If it's a certificated aircraft here's what I was referring to -

Part 43 Appendix A - Major alterations



Part 43 Appendix B - Recording of major alterations




A non-PMA'd engine heater is an accessory which is not approved for the engine, therefore it is a major alteration and requires a 337 approval by the local FSDO. Some FSDO's may grant it, some may not. By having the PMA we have removed from our customer the burden of obtaining FAA approval. A PMA'd engine heater is a minor alteration requiring just a logbook entry by the mechanic - no 337 is needed. Installation on a certificated aircraft of any heater that is not FAA approved might save you a few bucks, but balance that against the risk of engine damage (no thermostat, no FAA approved testing), legal liability, denial of insurance coverage, and FAA trouble.