Preheat

[ncdmtb]

I am looking for some advice on preheating.

My plane is in an unheated hangar. I fly at ground temps of slightly below freezing.

Should I preheat? What do I need/ what should I do?

[mike_elliott]

I am looking for some advice on preheating.

My plane is in an unheated hangar. I fly at ground temps of slightly below freezing.

Should I preheat? What do I need/ what should I do?

 

 

Yes you should. What I did when I was in Indianapolis, was to leave my engine pad heater plugged in all the time when temps were below 45, and I also ran a closed loop dehumidifier into the crankcase and kept a blanket on the cowl and cowl plugs in. Warm arid atmosphere inside the crankcase at all times coupled with nickel cylinders kept the corrosion concerns down. I know some will shriek with horror over leaving a preheater on all the time, but after 12 years of this practice, I have not been able to detect any corrosion in the engine occurring and cold starts are, well, they just really are a no factor. Now that I am in Florida and someone asks me what the heat sump plug is for, I tell them it is a new Electric engine STC I am working on

YMMV, but it sure worked for me for many years. Now I just have to make sure everything is corrosion proofed constantly here in FL.

 (Boshield and AFC 50 are my friends)

[carusoam]

It is considered good form to preheat when air temps are below 40degF.

It is somewhat mandatory to preheat when air temps go below 20degF. Partial pressure issue for 100LL.

Electric preheat is most convenient. There are cell (handi) phone switches available that aid in this effort.

Sorry about the English units. They are probably not exact, but they are the ones I use.

Best regards,

-a-

[rocketman]

As you know most engine wear according to some people in the know believe that most engine wear occurs during start up especially on cold mornings where the oil is slow to lubricate the upper reaches of the engine. So for me engine preheat is an absolute requirement. Where to began heating at a certain temperature is where some disagreement might exist. 20 degree F - Absolutely. 32 degrees - probably. 40 degrees - probably not. Lots of variables. Remember to check the temp in the hanger, not outside. Its usually warmer especially if their insulated. Also if the plane sits in freezing conditions overnight and the temperature warms up quickly to 40 degrees, I doubt the engine oil will heat that quickly so even though it might be 40 degrees outside, the oil temp might still be much less and probably still needs pre-heat.

 

I have 3 engine preheaters for my three Mooney's - a Reiff on my 201, a Tanis on my Bravo, and I use an Aerotherm Turbo for my rocket. Which one is best? Who knows. And I will probably never know.

 

Some people believe in Incandescent light bulbs for a slow maintenance heat. Good idea. But if your interested, better go out and buy them quickly. Their coming off the market very soon.

[orionflt]

I have been doing the light bulb trick vs the engine heater. The air temp here was in the 20's soi made it a point to go see what my engine temps were and I was surprised to find everything was sitting around 50 deg. This just made it easy to decide not to install an engine preheater.

[isaacpr7]

I have been doing the light bulb trick vs the engine heater. The air temp here was in the 20's soi made it a point to go see what my engine temps were and I was surprised to find everything was sitting around 50 deg. This just made it easy to decide not to install an engine preheater.

Do you have any pics of the setup you use? What kind of wattage and how many light bulbs do you use?

[231Pilot]

I've used Aerotherm since 2007.  Works great, thermostatically controlled, so it keeps air temp in the cowl at 60˚F.  You can make it higher, but there is no need.  I use an old comforter draped over the cowl to help hold in the heat.

[Bob_Belville]

Despite the picture, I don't try to heat the cabin any more. I put both ducts into the cowl flap openings. The ceramic heater has a thermostat -- all the engine temps on the JPi show at least 70F all winter.

[Jsavage3]

Do you have any pics of the setup you use? What kind of wattage and how many light bulbs do you use?

Here's what I've found to work well for me...

 

First of all, I live in Ohio and I fly all winter long.  

 

When I drive to the airport with the family for a trip, I do not like sitting around waiting for an hour while the Tanis engine heater heats things up.  Now what?  Simple, cost effective & minimal hassle is required...so...

 

I use a single 100W lightbulb (Bayco 150-Watt Incandescent Portable Work Light and Item #: 203213 |  Model #: FL-300NPDQ12 at Lowe's for $7.95) with a 50-foot extension cord and a ThermoCube TC-3 (electric ON at 35 degrees F and OFF at or above 45 degrees).  I run the bulb up the left cowl flap and secure it with the clamp such that the bulb itself doesn't touch anything.  After that, I use a rolled up towel to plug both cowl flaps...oil door closed...cowling inlet plugs in place as well.  After that, just plug it in.  My entire engine compartment never gets below 35 degrees...on a frosty morning, EVERYTHING inside the cowl feels warm-n-cozy to my cold hand...

 

So, when I arrive on that cold morning, I first turn on my heater (Lasko Utility Ceramic Compact Personal Electric Space Heater Item #: 5445 |  Model #: 675919 at Lowe's for $50) with 20-ft long, 6-inch diameter flexible & heat-resistant duct (hose) and run that into the baggage compartment door to heat the cabin.  While that's preheating the cabin, I usually pre-flight the bird (which includes unplug the cowl flap openings, turn off the engine compartment bulb and remove it) while my family sits in the warm car and watches...

 

Arrive-to-airport to taxiing is usually 15 min tops (does depend on how many bags I have to load) with minimal hassle, family stays warm (and HAPPY which translates to they want to go flying with me again sometime), we climb into the bird without coats on and crank up without cold issues.  If at the destination I'm going to be sitting out somewhere in the cold all day, I take a 100-ft extension cord, my clamp-lamp (spare bulb doesn't weigh much either) and a couple of rolled towels with me...

 

I've always used 32 degrees as a cut-off for whether to preheat or not, but you would never be wrong for preheating at a warmer temperature.

[AmigOne]

I've used Aerotherm since 2007.  Works great, thermostatically controlled, so it keeps air temp in the cowl at 60˚F.  You can make it higher, but there is no need.  I use an old comforter draped over the cowl to help hold in the heat.

I just bought a new comforter, King size, for about $40 (reduced from $90) from overstock.com. Most likely not of premium quality but given its size I can double it up over the cowl to provide adequate insulation given that my airplane is hangared. Next I'll buy one of this infrared thermometers to check oil and cylinders temp. I guess that if I point the beam down the oil filler tube I should get some reading. Has anybody tried that? My 0 time engine has not been started yet after the o/h so I am going to try every trick on the book (short of tannis or reiff), including the lamp bulb to keep the engine warm. Up to last year I was using the ceramic heater with the hose pointed to the bottom of the engine and I will do that too. The oil always looked fluid enough after an hour using the heater so with all the additional stuff (comforter, lamp) it should be OK. In northern Virginia it gets cold but seldom below 20F.

[isaacpr7]

Despite the picture, I don't try to heat the cabin any more. I put both ducts into the cowl flap openings. The ceramic heater has a thermostat -- all the engine temps on the JPi show at least 70F all winter.

 

Bob,

 

Does that ceramic heater have a blower on it to push air? If so, how strong does it have to be? How many watts? I would really like to try your setup. Also, how did you attach the duct work to the heater without damaging it?

[Bob_Belville]

Bob,

 

Does that ceramic heater have a blower on it to push air? If so, how strong does it have to be? How many watts? I would really like to try your setup. Also, how did you attach the duct work to the heater without damaging it?

Isaac, I looked around for the model for the little heater when I made the post last light, I will keep looking and post later. The heater has a built in fan. The duct is standard clothes dryer duct from Lowes Haredware. The heater has 2 knobs on top, one is a fan speed/off, the other is a rheostat/thermostat. Since the sensor is at the heater it does not "know" what the engine compartment temp is but runs the heater based on the temp in the hanger. @ about 1/3 on the heater runs the heater/fan when the ambient is about 50F. 

[orionflt]

Do you have any pics of the setup you use? What kind of wattage and how many light bulbs do you use?

Right now I am just using a regular work light with a 100 watt bulb plugged directly in. I have a temp controlled switch that is used to turn pipe heat tape on and off that I haven't put in line but that will turn the light on at 38 deg and off at 50 (outside air temp). A friend of mine is working on a control system that will monitor cowl temps and adjust power to a heat source to maintain a a continuos temp. His latest version uses a blue tooth temp sensor and a small ceramic heater, the system also monitors humidity. I'm finding that all the gadgets are more glamour then necessity but they are fun to play with.

[Bob_Belville]

I was by the airport this afternoon... the Holmes heater I have is like this one priced @ $28 at Home Depot. A 3 speed fan and a manual thermostat. Works great. The clothes dryer duct work is simply wired onto the exit grill of the heater. 

 

 

http://www.holmesproducts.com/heaters/HCH4051-UM.html#start=3

[ken66770]

My setup is much like the previous post from Bob_Belville. The heater is a Stanley pro-Ceramic from Lowes - $50. It has an adjustable thermostat on the top.The duct work is a 4"X8' expandable dryer duct coupled to a 4"X12" floor vent with an adapter found in the floor vent department. I drilled holes and used sheet metal screws to help hold everything together. With a little trimming with sheet metal shears, the floor vent fits perfect over the front of the heater. The entire setup cost us less than $75.

 

 

[Bob_Belville]

My setup is much like the previous post from Bob_Belville. The heater is a Stanley pro-Ceramic from Lowes - $50. It has an adjustable thermostat on the top.The duct work is a 4"X8' expandable dryer duct coupled to a 4"X12" floor vent with an adapter found in the floor vent department. I drilled holes and used sheet metal screws to help hold everything together. With a little trimming with sheet metal shears, the floor vent fits perfect over the front of the heater. The entire setup cost us less than $75.

 

2013-12-16 16.04.44.jpg2013-12-16 16.07.17.jpg2013-12-16 16.09.18.jpg

Basically the same, but yours is much better looking! 

[isaacpr7]

Isaac, I looked around for the model for the little heater when I made the post last light, I will keep looking and post later. The heater has a built in fan. The duct is standard clothes dryer duct from Lowes Haredware. The heater has 2 knobs on top, one is a fan speed/off, the other is a rheostat/thermostat. Since the sensor is at the heater it does not "know" what the engine compartment temp is but runs the heater based on the temp in the hanger. @ about 1/3 on the heater runs the heater/fan when the ambient is about 50F. 

Thanks for the help Bob. I just purchased a heater similar to yours today at wally world for about 18 bucks. I bought a 4" flex duct and a flat piece of sheet metal from home depot with a 4" hole. I am going to attach the plate with the hose installed into the grill to get it looking as close as possible to your setup and give it a try. I was not a happy camper today when I tried crank the aircraft multiple times and it would not start. I guess I neet to hurry up and build some sniffle gear for the enging

[AlanA]

17 degree this morning at the airport.  Single digits overnight.  Used a Red Dragon Propane heater to warm the engine and cabin.  Heated for an hour but I think I could have cut that time in half and it still would have been adequate.

[flyingvee201]

I read somewhere that Tanis now has a heating element that replaces the rocker cover gasket?

If you have the CHT probes and dont want to use their CHT/heat probe combo, this sounds like a good idea.

[isaacpr7]

One more question for you guys. Do you normally leave the heater running 24/7 or do you only leave it on the night prior to flight?

[Rich]

I preheat even in the 50's. As I understand it, you should not leave the heater on 24/7 w/o humidity control in the engine.

[RJBrown]

There is no electricity to the shelters where I was parked. With the MSE there is a tanis and I would chain a small generator to the post overnight. With the Rocket it had no built in preheater. I made up a preheater from a 115v propane space heater from Home Depot, a small inverter to run it off the car battery and some HVAC tin and some scat tubing.

 Pre heat below freezing. 40 degrees maybe not.

[aaronk25]

One more question for you guys. Do you normally leave the heater running 24/7 or do you only leave it on the night prior to flight?

 

It is ok to run the tanis/reiff 24/7 given you have foam cowl plugs installed.  A blanket over the cowl is also very effective and raises temps even higher.  By installing cowl plugs (and closing the cowl flaps) the cowl air surrounding the engine is warm and the dew point is moved outside of the engine.  If a engine has been sitting plugged in try removing a cowl plug and feel how warm the air is inside the cowl.  Warm Dry Air.

 

If you leave the preheat device on with out cowl plugs the air side the cowl is closer to ambient and the dew point is moved either into the engine or somewhere close to it.  If it ends up being inside the engine moisture can cause rust.

 

In fact I can prove it.  My plane is plugged in right now and my last  Blackstone oil analysis have shown ZERO moisture content.  In fact I believe it actually dries the engine out as if the air is 60 or so around the engine and the engine is 70 there is a heck of a spread in dew point.  

 

now move the temps down without leaving it plugged in and the dew point gets lot closer, plus if there is any moisture left in the engine from operation it doesn't dry out!!!!......it pays to leave your engine plugged in with cowl plugs installed 24/7, even if your not going to fly it. 

 

Anyone that says that operating a engine heater 24/7 with cowl plugs installed, will promote moisture inside of the engine is full of baloney.  

[mike_elliott]

It is ok to run the tanis/reiff 24/7 given you have foam cowl plugs installed.  A blanket over the cowl is also very effective and raises temps even higher.  By installing cowl plugs (and closing the cowl flaps) the cowl air surrounding the engine is warm and the dew point is moved outside of the engine.  If a engine has been sitting plugged in try removing a cowl plug and feel how warm the air is inside the cowl.  Warm Dry Air.

 

If you leave the preheat device on with out cowl plugs the air side the cowl is closer to ambient and the dew point is moved either into the engine or somewhere close to it.  If it ends up being inside the engine moisture can cause rust.

 

In fact I can prove it.  My plane is plugged in right now and my last  Blackstone oil analysis have shown ZERO moisture content.  In fact I believe it actually dries the engine out as if the air is 60 or so around the engine and the engine is 70 there is a heck of a spread in dew point.  

 

now move the temps down without leaving it plugged in and the dew point gets lot closer, plus if there is any moisture left in the engine from operation it doesn't dry out!!!!......it pays to leave your engine plugged in with cowl plugs installed 24/7, even if your not going to fly it. 

 

Anyone that says that operating a engine heater 24/7 with cowl plugs installed, will promote moisture inside of the engine is full of baloney.  

 

When I was in indy, I ran mine 24/7 when it was below 45. I also had a closed loop dehumidifier pumping dry air into the crankcase for good measure. As Aaron said, no moisture issues in any oil samples for over 10 years in mine.

Now I don't have that problem , altho it did get down to 55 last night

[isaacpr7]

Guys, thanks to your guidance I think I was able to pull off rigging a preheater for a very cheap budget. I bought a 1500 watt ceramic heater at Wally world for 18 dollars and a sheet metal plate with 4" hole for 3 bucks. The 4" duct was about 8 bucks and VIOLA! It works geat!