Backcountry Pilot • Forced Air Engine Pre-heaters

Forced Air Engine Pre-heaters

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Re: Forced Air Engine Pre-heaters

I guess I need to throw in my 2 cents. I have had a Reiff Standard system on my airplane since soon after I bought it, almost 16 years ago. As long timers here know, my engine croaked after only 15 hours from purchase and I landed in a field. I'd already installed the Reiff, so it was transferred to the new engine. I also have a Kennon cowl cover plus prop and spinner covers. All of that makes a huge difference in the ability to start the engine, which pretty consistently stays at about 60-65 CHT degrees without the cowl, prop, and spinner covers and about 20 degrees warmer with them on, no matter the outside temperature.

My airplane is in an unheated, drafty hangar, but for all practical purposes, there's no real wind. I have used the system outside, though, and as long as the covers are on, the temps are similar to above.

Mike is right on about covers. I have landed in 0 degree temperatures, covered up with all the covers, and 4 hours later, the engine is still holding the temps in the 80s. FWIW, though, even without the covers, if I put cowl plugs in place, the engine will hold the temperature well in pretty cold OAT for a couple hours or so.

For myself, I can't see using a cobbled system on my airplane. I like the Reiff system, it works, and on my engine which cost me $23,000 15+ years ago, the $460 it cost then ($490 now) seems pretty reasonable. I don't understand the unwillingness to buy a proven system that does the job well, as opposed to cobbling something up that may or may not work and may or may not do damage.

Incidentally, although I bought an Alaskan Companion preheater from someone here, I've never used it and might not. I'm always leary of hot air, ever since I saw a rampy cook the cowl of a 172 with a salamander, when he left it on too long. Amazing the damage too much heat can do to the paint on a cowl. But I guess it would be better than nothing, if I watched it carefully and there was no electricity to use the Reiff.

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Re: Forced Air Engine Pre-heaters

I made my own system. It is a ceramic space heater from Home Depot with a reducer duct I modified with pop rivets and a piece of metal dryer hose. I put it on a timer so it isn't on continuously, but fires up each morning at about 7:00 in case I want to go flying at 10:00. It works fine, but this isn't the coldest place on the continent. The heater has lots of different settings if you want to choose one that would allow you to leave it on continuously.

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Re: Forced Air Engine Pre-heaters

The problem with ALL forced air heaters is that they have a fan. And, fans have lubricants. Because most of the manufacturers of these things don't have a clue where you'll be using them, those lubricants can vary a lot in "thickness".

A hard and fast rule I always used when first plugging in a fan forced heater in Fairbanks (not in my airplane mind you) was to plug it in in person, then listen to ensure that fan actually starts and runs. And, yes, I've plugged one in and the fan didn't start up.

Most of these things have an overheat fuse that turns the thing off if it overheats. Remember, that fan not only distributes heat, its main function is to prevent the heat device from overheating. Ceramic heaters are SUPPOSED to be safer, but, are you willing to bet your airplane on that?

Second point: While there's a lot of discussion and many opinions about whether you should pre heat continuously or only when you plan to fly, but most everyone I know that has some experience in cold country will absolutely say if you pre heat it, you really SHOULD try to fly it.

When you preheat, then just shut it off, you are creating a magnet for moisture in that cowling due to condensation. The only way you're getting rid of that moisture generally is to fly it and get the engine up to operating temperature.

I might keep my pre heater plugged in all winter, but I would NEVER pre-heat every morning, on the chance that I MIGHT fly it.

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Re: Forced Air Engine Pre-heaters

Arctic Flyer wrote:There are different ways to preheat.

Then there is the right way.

1) buy a good engine cover. Make sure it’s long enough to cover all your cowling openings. Including underneath. Nothing steals your heat like the wind.

2) install a Reiff or a Tanis. Ford/Chevy, Miller/Budweiser; everyone has there preference.

3) install a bootcowl plug-in with a dummy light. This keeps the extension cords away from the cover and let’s you know you have power to the plane.

4) install a pig tail cord into the cabin. Plug your thermostat controlled heater into it and care for your interior instruments, etc. I set mine on a cookie tray because it makes me feel better.

This is a recipe for success. We are hearting different types of metals, oil, air, etc. All of these things accept heat at different rates. Low and slow heat will warm to the core. The goal isn’t to cook an egg on your artificially hot cylinder surface but get heat deep down into the engine. Heat overnight or leave plugged in for longer and then fly your plane and achieve appropriate oil temperatures.

I have the unfortunate experience (15 years) of flying winter/spring in northwest Alaska without a hangar. Take care of your engine, because you want it to take care of you.


What he said......listen up, folks....this is indeed the voice of experience.

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Re: Forced Air Engine Pre-heaters

Lol. This guy gets it
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Re: Forced Air Engine Pre-heaters

I’ve had reasonable success with the red dragon so far. Haven’t gone into the single digits F yet though.

We have a 12 foot duct and stick one end of it in a cowl flap. It fits about right. Engine cover stays on. Then I let it go for about 30 minutes while I preflight and remove the other covers, keeping a close eye on the heater.

After 30 mins when I feel around inside the engine compartment the jugs are warm, oil flows smoothly off the dipstick, and everything in there feels warm to the touch. Engine starts up pretty nicely.

I wonder if I should be moving the duct to the front/top of the cowl after 15 or 20 mins, but keeping it coming up through the cowl flap and using the principal that warm air rises seems to work ok.

I need to workout the temp/time formula on how long we can shut down on a stop someplace before cover/more heat is required. 1 hour at 20 F after a 1 hour flight before heat is needed again? I don’t know.

Also the motor still has “Aeroshell W100/50WT” in it from a September pre purchase oil change. I understand this to be the intermediate temperature Aeroshell, probably not ideal. Since we are approaching the 4 month mark, I might switch to the W80.
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Re: Forced Air Engine Pre-heaters

Flyhound wrote:I made my own system. It is a ceramic space heater from Home Depot with a reducer duct I modified with pop rivets and a piece of metal dryer hose. I put it on a timer so it isn't on continuously, but fires up each morning at about 7:00 in case I want to go flying at 10:00. It works fine, but this isn't the coldest place on the continent. The heater has lots of different settings if you want to choose one that would allow you to leave it on continuously.

Image


I had a similar setup for my 182. I actually had another one for the cabin area. Worked great.
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Re: Forced Air Engine Pre-heaters

akschu wrote:
Reptile heaters, that's clever, but the zip ties on your engine mount are freaking me out. Especially the extension cord. That one is high risk to cut through and short some mains power right next to your engine mount.


Hmm, I'll have a look at those the next time I've got the cowling off. The extension cord was installed as you see in the picture by an A&P and has been there for 15 years. My AIH drop lamp sockets don't have super heavy duty cords, but I also have them zip-tied in similar fashion. What's the best method?


"Proper" technique is to use two zip ties. Put one around the cord and then hook the other through it and warp it around the structure. Then pull both tight. Think two linked rings with the cord going through the middle of one and the structural tube going through the other.

But truthfully if your setup has lasted 15 years without a chafe problem and your A&P/IA is good with it don't worry.
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Re: Forced Air Engine Pre-heaters

I recently just built a cell backed switchbox and gave it to my bud that has a small ceramic heater:

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It's just like any other commercially available switch box where you use and app/website to turn it off and of, except one notable exception. I also include a temp probe that you run up into the cowl. It's the wire you see going vertical over the duct. This gives you the ability to see that the heater is working and it also gives you an idea of what your under cowl temps are before you head to the field.

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Looks like his engine is 40.887501 degrees F and the power is off.

So far it's working nicely for us. Perhaps I should add a feature to turn off the switch if we don't see it heating up in the first 10 seconds.

schu
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Re: Forced Air Engine Pre-heaters

Way cool schu! I’ll take one. It comes with an app, right?[emoji6]

My two 75W incandescent lights are working acceptably. I leave them on all the time and with days in the high 20s and nights in the single digits the engine stays around 45-50F. I’d prefer warmer but anything above 40 is acceptable. I have a small ceramic heater that fits nicely inside the cowl that I turn on if I know I’ll be going flying.
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Re: Forced Air Engine Pre-heaters

It's a desktop and mobile-optimized website. No reason to make an app when you can do tons of app stuff right in a web page.

I've been thinking about building and marketing these because my design is much better than what is available, and because I have some ideas to add some features far beyond just a dumb switch.

I think my design is better because:

It wouldn't require you to sort out the cellular part on your own or get a sim card or any of that. Instead of paying $10 a month to a cell provider, you would pay $10 towards the service I would build and it would manage the cell service, access to the box, and continual development of the web app.

My design has a temp probe and the possibility of much more.

My design doesn't have current limitations due to poor quality relays. You could plug a 2000w inductive load into my box and it wouldn't care.

Problem is they will cost $250ish by the time they are made, the end-user will need to part with $10 a month, and in order to have a good quality product I'd have to spend some time building a custom housing, refining my wiring inside to make it easier to build, and tons of time into the webapp.

If there was a bunch of interest, and lots of people wanting a really nice box they didn't have to fight with that could flip on a space heater if they wish, then I may go forward, but right now I don't think there is enough interest to make it worth my time.

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Re: Forced Air Engine Pre-heaters

https://www.ebay.com/itm/All-In-One-12V ... %7Ciid%3A1

I have been using one of these this year. Works awesome so far. I have used one in a boat for several years as well.

Yes it has a fan, it also has a sealed combustion chamber so there are no fumes coming out the business end just nice clean hot air. On my brothers 170B using a good cowling cover, in one hour it went from 19 degrees to 110 degrees on the cylinder temps and 90 degrees on the oil.

A 3" scat tube on the front of the heater puts the heat wherever you want it. Toss the tube inside the cabin and everything is thawed out and warm in no time and you don't have the moisture issues you have from a red dragon. The gallon of diesel will last you over 24 hrs of run time. I also strapped it down in the bed of the side x side and ran the scat tube into the cab. Keeps it nice and toasty in there at sub zero temps. Works great for a tent heater too.
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Re: Forced Air Engine Pre-heaters

$140 undercabinet 1kw forced air heater (120vac) from Home Depot.

$16 16' 12AWG extension cord to wire in from HD.

$14 digital thermostat from HD-set a schedule if you like

$12 24vac transformer from HD

$8 for 10' of thermostat wire from HD

$7 aluminum dryer vent. Home depot

$14 square duct adapter. Home Depot.

$6 metal duct tape. Home Depot.

$120 GSM switch with a $10 consumer cell chip in it. Turn the heater part on and off at will via SMS, leave the thermostat on to keep the schedule. Then you don't have to get up at 430 am to turn on for a 6am flight. Turn it on the night before. It will turn on automatically for you while you sleep.
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Re: Forced Air Engine Pre-heaters

Lesuther, can you post a photo of your heater set-up? Thanks.
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Re: Forced Air Engine Pre-heaters

Went flying yesterday morning. It had been cold overnight and was -1F when I arrived at the airport. One of the light bulbs had exploded leaving a mess of glass in the bottom of the cowl. A single 75W was only able to maintain engine temps in the mid 20s at those OATs. I have a small heater that fits in the cowl so I put that in for 90min or so.

I don’t know why the bulb exploded but it makes me nervous. I’d really like a system I can leave on all the time but I think we’ll probably end up with a reiff and a remote switch.
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Re: Forced Air Engine Pre-heaters

I was grappling with two aspects of heating, in the hanger and on the road. The hanger component has been resolved with a lightweight, propane fueled heater. I have determined that with proper time management I can complete the required pre-heating whilst performing the other per-flight duties, thankfully time is my own and I'm not rushed to depart at all.

So now for the "on the road" requirements, my "inner" McGyer was sparked by an earlier poster on the subject and a recent visit with a very creative local aviation AME. I now have a very lightweight, compact, travelling preheater or better called a "heat maintainer" that utilizes a single burner, dual fuel, camp stove, some simple duct component and a well fitted engine cover. As an added bonus I can warm up a bowl of soup of hot chocolate while I'm wait for SAR should the need arise

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This has been a very informative and formative topic for me, thank you BCP's.
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Re: Forced Air Engine Pre-heaters

whee wrote:Went flying yesterday morning. It had been cold overnight and was -1F when I arrived at the airport. One of the light bulbs had exploded leaving a mess of glass in the bottom of the cowl. A single 75W was only able to maintain engine temps in the mid 20s at those OATs. I have a small heater that fits in the cowl so I put that in for 90min or so.

I don’t know why the bulb exploded but it makes me nervous. I’d really like a system I can leave on all the time but I think we’ll probably end up with a reiff and a remote switch.


Wow...I don't think I've ever seen a light bulb explode unless something hit it.

The Reiff has a thermostat, so I don't see any reason you couldn't leave it on all the time if you were so inclined. It seems like a lot of money, but once it's on you don't have to think about it anymore.

I've looked at cellular switches since I do not want my heater on all the time. They seem to be of limited value to me, since there's no cell reception where I live, and no internet at the hangar. If I was smarter I'd figure out a switching system that utilizes DTMF, as I can hit the hangar from my house with a ham radio.
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Re: Forced Air Engine Pre-heaters

https://division-6.com/products/dtmf4-dtmf-relay-board/

A handheld transciever and the above product would allow DTMF control.

I have a cell switch, and had never considered Ham... I might not have to spend $3 per month...
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Re: Forced Air Engine Pre-heaters

jcadwell wrote:https://division-6.com/products/dtmf4-dtmf-relay-board/

A handheld transciever and the above product would allow DTMF control.

I have a cell switch, and had never considered Ham... I might not have to spend $3 per month...


Thanks for the link...I forwarded it to someone who actually has the ability to make things. I'm pretty inept...particularly with electricity.

There are some plug-n-play options out there, but they're unrealistically expensive for my needs:
https://www.twowayradio.com/ritron-tele ... 42-on.html

I particularly like this application of the switch...soooo annoying!
http://pro2way.com/wireless-portable-pa ... loldp2thp0
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Re: Forced Air Engine Pre-heaters

akschu wrote:It's a desktop and mobile-optimized website. No reason to make an app when you can do tons of app stuff right in a web page.

I've been thinking about building and marketing these because my design is much better than what is available, and because I have some ideas to add some features far beyond just a dumb switch.

I think my design is better because:

It wouldn't require you to sort out the cellular part on your own or get a sim card or any of that. Instead of paying $10 a month to a cell provider, you would pay $10 towards the service I would build and it would manage the cell service, access to the box, and continual development of the web app.

My design has a temp probe and the possibility of much more.

My design doesn't have current limitations due to poor quality relays. You could plug a 2000w inductive load into my box and it wouldn't care.

Problem is they will cost $250ish by the time they are made, the end-user will need to part with $10 a month, and in order to have a good quality product I'd have to spend some time building a custom housing, refining my wiring inside to make it easier to build, and tons of time into the webapp.

If there was a bunch of interest, and lots of people wanting a really nice box they didn't have to fight with that could flip on a space heater if they wish, then I may go forward, but right now I don't think there is enough interest to make it worth my time.

schu


I am local to you and would pay $250 for your product
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