bob865

My Engine Heater

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17 hours ago, Yetti said:

and possibly the cabin too?

I have considered getting a T fitting to put air into the cabin and into the cowling so I get into a warm plane too.  It's always an option.  Just more hardware to transport though.

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16 hours ago, jaylw314 said:

Also, I'm not clear on how the heater works--does it actually burn the diesel and use the exhaust gas, or does it convert it into electricity and then heat an electric element?

Like @larryb said, they are separate.  I will try to take a picture of the back of the box when I get home so you can get a better idea.

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17 hours ago, DonMuncy said:

I fitted my plug-in heater with a 4 inch semi-flexible (think clothes dryer) hose. I stick it up into the cowl flap and crack the oil filler door on top to allow some movement of air.

I actually get better results by keeping the oil filler door closed and a blanket in top.

It seems like the hot air rises from the heater tube in one cowl flap and then the cold air is displaced to exit from the other cowl flap, maybe?

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55 minutes ago, Andy95W said:

I actually get better results by keeping the oil filler door closed and a blanket in top.

It seems like the hot air rises from the heater tube in one cowl flap and then the cold air is displaced to exit from the other cowl flap, maybe?

You are probably right. I haven't used mine enough to get any worthwhile experience.

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2 hours ago, Andy95W said:

I actually get better results by keeping the oil filler door closed and a blanket in top.

It seems like the hot air rises from the heater tube in one cowl flap and then the cold air is displaced to exit from the other cowl flap, maybe?

That would make sense for a 60W light bulb or small heater, no sense opening up the oil filler door.  The warm air will simply rise to the top, and cooler air will come out the other cowl flap.

For a more powerful heater, I suppose it might be helpful to open the oil filler door to keep the accessory compartment from getting baked, but I imagine it'd have to be a pretty powerful heater!

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My propane setup produces twice yours, 35000 BTUs and it takes between 20 and 30 minutes to pre-heat when the OAT is -20C. I’ll post a picture when I get home. While the aircraft is at annual, I decided to replace the 4 inch pipe and some other fittings. Have been using it for a few decades and it never let me down.

Yves

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39 minutes ago, jaylw314 said:

That would make sense for a 60W light bulb or small heater, no sense opening up the oil filler door.  The warm air will simply rise to the top, and cooler air will come out the other cowl flap.

For a more powerful heater, I suppose it might be helpful to open the oil filler door to keep the accessory compartment from getting baked, but I imagine it'd have to be a pretty powerful heater!

This is a great point- my heater is a fairly small one - 1500W.  I use it to supplement my Reiff on really cold Michigan days.

 

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9 hours ago, yvesg said:

 when the OAT is -20C.

Yves

I am just going to put it out there that if the OAT were to ever hit that, I am packing and moving further south.

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On 2/14/2018 at 8:48 PM, yvesg said:

Here is the device:

 

6B2CCC02-D148-455C-89A5-E701A4EE6E4F.jpeg

That kind of heater requires to be plugged in correct?  That's why I went the route I did.  I don't have a place to plug a heater in.  Otherwise I would have chosen some electric options.

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Congrats to the OP, that is a really clever set up.  That said, I wouldn't fly it inside the airplane on a bet.  Sorry, that fuel container doesn't look like it would survive a trip to high altitude.  I could be wrong, just what it looks like.  I take fuel to any altitude its in a camping bottle built to do so.  Putting anything flammable in the aircraft gives me the willies.  During the winter in the North most of my stops are sufficiently short that the engine doesn't cool down, especially with my cowl plugs in it.  

Actually, I have a little heater from aircraft heaters.com.  I usually carry it and an extension chord during the winter, and if I do stay for awhileI plug the thing in.  I've yet to travel to an airport where I couldn't find some electrical power. If I'm going to stop for that much longer I pony up for a heated hangar.

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8 hours ago, bob865 said:

That kind of heater requires to be plugged in correct?  That's why I went the route I did.  I don't have a place to plug a heater in.  Otherwise I would have chosen some electric options.

This one requires 12V for the fan. I replaced the 120V AC by a car heater fan motor. I usually carry an emergency battery power pack which has cig lighter outlet. I made the cable long enough that I could reach the one in my car. However they do sell such devices with integrated batteries like this one: http://www.mrheater.com/35-000-btu-hero-heater.html

Yves

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Thought I'd add to this, as thanks to the original idea, I went ahead on one of these.

The only power I have at my home 'drome is via a generator, and I wanted something I could take with me too, as hangars for visitors can be quite difficult when touring. I also wanted something that could be used to eg heat a tent, or even potentially for working in the hangar.

Things I wanted over Bob's original design were less protrusions on the exterior, able to be left as well as used outside (less susceptible to rain), and possibly a greater autonomy. If it could be more rodent-proof that would be an advantage, as would making it resistant to spills (I think the smell of diesel/jet fuel/heating oil in a confined space particularly nauseating)

After getting the bits and starting to assemble, I wish I'd done more research before! In Europe, heaters like these are frequently found in boats and motorhomes, and sometimes the long distance trucks. They're often known by the trade name "Eberspacher" https://www.eberspacher.com/ where a D5 model equivalent from ebay could be had for less than USD250. The D5 uses up to 0.6 liters (a litre is near a dammit a quart) per hour foor a 5500W output

After the heater itself, a tool box from a local DIY store (expensive - this is Switzerland!, but at least I could see what was inside etc before buying), fuel tanks, batteries, charger and some odds and ends from a model shop (batteries for an RC model were more like the load profile than a motorcycle battery I thought), and a couple of evenings with a drill and knife.

Result:

Fairly standard looking toolbox from a distance (Oil cans for scale!)

20181110_152208.jpg.0bfb0ac17439620f70bc3406f06a85ea.jpg

On left, exhaust, charging socket and master switch, heater supplied control panel in the middle, thermometer stuck on the right

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Air inlet is via hundreds of small holes drilled below the drip line of the lid that continue round the tool box

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Hot air outlet

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All the gubbins:

By routing the exhaust inside of the box I expect some slight additional heat recovery! Fuel tank vents to felt air filter incorporates a non-return valve, but hoping that the loops in the vent lines will prevent the stuff getting that far - has bee tested in the roll 90 degrees either way about the long dimension. No so visible is the aluminium plate between the heater and the batteries - the idea here is to get some heat to the batteries (after all, it is being used in the cold!) to improve the capacity

20181110_152317.thumb.jpg.37abd18921a87d5a697c7704996a9c75.jpg

With exhaust extension (just visible extending out of the hangar door - I expect to put a hole in the wall at a suitable position in due course) and duct extension (short black length is what will be used to go up the cowl flap for engine heating) for use in the hangar:

20181110_152816.thumb.jpg.efce3933b05f1f0c3454b53baa75c638.jpg

Autonomy at minimum heat is in excess of 18 hours which is more than I needed. At maximum I'm expecting more than two hours, which should be more than enough for an engine pre-heat - maybe another report after the cold sets in (it has remained remarkably warm so far this autumn - maybe making a heater is going to give us a mild winter!!)

Edited by Awful_Charlie
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On 2/13/2018 at 8:13 AM, bob865 said:

I have considered getting a T fitting to put air into the cabin and into the cowling so I get into a warm plane too.  It's always an option.  Just more hardware to transport though.

I would not do that (again). The setup shown in this old photo resulted in a lot moisture condensing under the carpet. 

2013-02-06_16-38-22_587.jpg

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17 hours ago, Awful_Charlie said:

Autonomy at minimum heat is in excess of 18 hours which is more than I needed. At maximum I'm expecting more than two hours, which should be more than enough for an engine pre-heat - maybe another report after the cold sets in (it has remained remarkably warm so far this autumn - maybe making a heater is going to give us a mild winter!!)

Nice work!!  I definitely saw room for improvement after I built mine, and you did too.  Maybe I should have patented the idea so I can be like Garmin, if Garmin can sue everyone in aviation, why can't I? :lol:

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Keith,

Great pic!

for a few dollars more...

add another hose to bring the air back out the other inlet side...

recirculating the warmed air might cut the heating time down...

Increased temperature, with some convection... doesn’t have to perfectly mimic the airflow during flight to be effective.

Engineering ideas, not just a PP today...  :)

Best regards,

-a-

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Keith- I have the same set up, but with a smaller diameter hose.  I put it into one cowl flap, block off the front air intakes, and let the warm air rise.  Cool air descends and comes out the other cowl flap.

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Y’all mean like this setup?

This gets things up to about 140 or so after about 2 or 3 hours on a 20 degree night with blankets over the cowling and inlet plugs. Plus I like that oil sump, oil cooler, and cylinders are all heated fairly equally. @carusoam I really like the idea of convection, bringing a hose out the other cowl flap and attaching to the other side of the heater, might cut the heating times down and possibly warmer overall temps. 

I got a bill from some elf for about 50 bucks for this gem. It was made by the same elf who was inspired by a conversation among elves about LED recognition lights recently.

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OK, as you may have seen, it got quite a bit colder in the last week or two in Europe!

I set the heater up, fuelled with a mixture of heating oil (transpires that on its own this is too viscous at low temperatures for the fuel pump to manage), Avgas (to thin it down) and road diesel (to top it off). As I'd let the batteries go flat, I had to run it with a battery charger attached (hope the batteries recover after a full charge!) The initial draw is horrible (like 7-8 amps) but it settles down to about 2 amps when it's fully fired.

The temperature as shown on various thermometers in the hangar was +1dC, connecting the battery minder to the aircraft and running the JPI monitor gave 28dF for the imperial probes, and -4dC on the metric probes. As the snow was not so crunchy outside, I'm more inclined to think it was nearer +1dC than -5dC - probably about 0dC

Put the two top cowl plugs in, but no cover, and left the intercooler and induction plugs out. Heater took just over two minutes to fire up to hot output, and then put the heater output up the right hand cowl flap and set it to max (nominal 5.5kW of heat)

Took readings from the JPI every 20 minutes or so and plotted the resulting temperatures from the JPI. After half an hour, the right side of the cowl was warm to the touch (to be expected), but the induction and intercooler ducts were warm too, so put in those bungs.

As to be expected, the EGT's rose quickest (greater external surface area to mass ratio), and the right side warmed faster than the left. The oil temperature is as measured by the JPI (ie top of the crankcase just behind the prop) as I didn't have a thermometer that I trusted not to end up in the sump if I dangled it down the dipstick hole! Chart below, left temperature scale in dF, on the right in dC. Final sample is after 75 mins of heat, max output used the whole time, fuel consumption (approx 0.75 litre) suggests it is in the right ballpark. I would guess that if the heat was removed the temperatures would even out through conduction, but that will be another test another day, when I'll also look into possibly better duct positioning/sealing/direction to improve the distribution.

image.thumb.png.1b89a58ffe54ac7b15ffa543d1c31e35.png

My conclusion: It works, but 5kW is barely enough! Maybe a cowl blanket will help a bit, but I doubt even with that it will be easy to get the whole engine from freezing to +90dF in an hour

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Definitely like the box heater.

For those that are plugging in I purchased a cheap cell operated switch: 

https://www.amazon.com/OlogyMart-Controlled-Sockets-Controller-Temperature/dp/B07GRFX8XB/ref=sr_1_14?ie=UTF8&qid=1548622811&sr=8-14&keywords=remote+gsm+switch

T-mobile sim, $3.50 per month.

My engine has a heat pad on the pan and bands on the cylinders.  I send a text message 3 hours before I need to start and with a blanket the engine thoroughly warm.   I also have a ceramic type heater that I can leave in the cabin.

I also operate my LED hanger lights through this switch.

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