preheat with a heat gun?

[Derrickearly]

Has anyone had luck with using a heat gun to preheat you engine in the winter.  I've seen many clever solutions posted. I'm looking for something cheap and simple.

https://www.amazon.com/dp/B07FM974CY/ref=cm_sw_em_r_mt_dp_Q7bPFbZF24P1K?_encoding=UTF8&psc=1

[tmo]

Heating up the engine, with any means, will take time, I doubt a heat gun is the tool for it.

I think that for "portable" / "cb" solutions a decent space heater and tubing to pump the heat up the cowl flaps would be easiest, and that is what I'll be attempting to run with, topping it off with some insulation, or an engine blanket, on the top of the cowling, and plugs for the air inlets so the warm air stays under the cowl. Once I have it "under control" perhaps a remote starting mechanism, but that's low on my priority list since it's easy to start a fire if anything goes wrong.

[Tim Jodice]

I used a 1500 watt space heater with dryer duct through the cowl flaps and wrapped the cowl with a insulated hot water heater cover. I used one meant for a 80 Gallon tank and it almost wraps completely around the cowling. 

[Dale Logsdon]

I know a guy who uses a cheep hair drier he bought from Walmart and thinks its the best thing ever.

[Tcraft938]

Depending on the ambient temperature before starting the gun, it may take a very long time to sufficiently heat the engine compartment.  Also the heat gun provide extreme heat in a very small concentrated area, so be careful what you point it at and how close to it otherwise it could do a unfavorable job on things like paint, wires, etc.  When I had a 1946 Taylorcraft (I was the starter motor), my A&P one day gave me something he sewed from old sleeping bags.  It was insulation to put over the prop.  "Everyone covers the cowl but they overlook the prop which is a huge heat/cold sink".   To my surprise in similar conditions, the red dragon heater would get the compartment to temp 30 minutes sooner with the prop covered, and after flying the engine compartment would retain heat for several hours.  Of course he was also humorous saying they were pillows so the blades would be softer to my touch when I hand propped it.  :-)  

[Derrickearly]

26 minutes ago, Dale Logsdon said:

I know a guy who uses a cheep hair drier he bought from Walmart and thinks its the best thing ever.

Great! I selected this gun since my inverter can only handle 500W.  I'm planning to dial back the heat until the inverter is stable.

Edited November 5, 2020 by Derrickearly

[M20F]

REIF heater rings are inexpensive and do it right.  My two cents. 

[Derrickearly]

Just now, M20F said:

REIF heater rings are inexpensive and do it right.  My two cents. 

Agreed. I'll probably end up there.  Do you know the total watts for 4 cylinders and the oil pan heater?

[M20F]

1 minute ago, Derrickearly said:

Agreed. I'll probably end up there.  Do you know the total watts for 4 cylinders and the oil pan heater?

$400-$700 install is 2hrs at worst.
 

http://www.reiffpreheat.com/product.htm#System Summary

 

Edited November 5, 2020 by M20F

[Hank]

3 minutes ago, M20F said:

REIF heater rings are inexpensive and do it right.  My two cents. 

Tanis also works well, a heater pad on the oil pan.

[EricJ]

One concern with a heat gun is that the output temperatures can be very high, so be careful about damaging stuff close to it.    

[Derrickearly]

Just now, EricJ said:

One concern with a heat gun is that the output temperatures can be very high, so be careful about damaging stuff close to it.    

Thank you for the good advice. I'm planning on dialing it back to keep the output temp safe.

[Ragsf15e]

One other issue with a heat gun or anything else “quick” is that the engine and oil is a huge heat sink.  Nothing is going to happen real fast.  You can point 500 degrees of heat at cylinders 1/3, and you might even get the outside metal temps up pretty high, but did you heat the pistons and the oil?  Or #2/4?  Likely not.  You really need to get the entire engine (inside and out) and oil up to a reasonable temp.  no matter what, it’s going to take a little while.  Even if your cylinder temp says 100 degrees, where is that sensor and does that mean the whole engine?
 

If you want a good long term solution, reiff or tanis heats the oil and each cylinder.  You can look on their website, but even they will tell you it takes time from a cold engine.

If you want cheap (and not very mobile), a small space heater with dryer vent up the cowl works great.  I use it on the lowest setting.  I also have a text enabled power socket that I use to turn on the heater from home. I typically turn it on the night before.  Outside temps of 10 degrees yield oil and cylinder temps of ~70 (it’s in a hangar).

[Derrickearly]

4 minutes ago, Ragsf15e said:

One other issue with a heat gun or anything else “quick” is that the engine and oil is a huge heat sink.  Nothing is going to happen real fast.  You can point 500 degrees of heat at cylinders 1/3, and you might even get the outside metal temps up pretty high, but did you heat the pistons and the oil?  Or #2/4?  Likely not.  You really need to get the entire engine (inside and out) and oil up to a reasonable temp.  no matter what, it’s going to take a little while.  Even if your cylinder temp says 100 degrees, where is that sensor and does that mean the whole engine?
 

If you want a good long term solution, reiff or tanis heats the oil and each cylinder.  You can look on their website, but even they will tell you it takes time from a cold engine.

If you want cheap (and not very mobile), a small space heater with dryer vent up the cowl works great.  I use it on the lowest setting.  I also have a text enabled power socket that I use to turn on the heater from home. I typically turn it on the night before.  Outside temps of 10 degrees yield oil and cylinder temps of ~70 (it’s in a hangar).

I agree.  My plan is to rest the heat gun on top of the engine making sure the exit temp is safe.  Then install the cowl plugs and leave it to warm the engine. My inverter only supports 500w, so that's the most I'll be able to pump into the engine compartment.  I'll give it a try and see if it works.

[Vance Harral]

1 hour ago, Derrickearly said:

My plan is to rest the heat gun on top of the engine making sure the exit temp is safe.  Then install the cowl plugs and leave it to warm the engine.

Please consider an arrangement that keeps the gun itself outside the cowl, and directs the hot air it blows up through the cowl flap.

For one thing, hot air rises, so blowing hot air along the top of the engine is not going to be very effective in heating it.  More importantly, though, a number of things can go wrong with the arrangement you propose.  Some are admittedly small risks, like accidentally catching the frame of the gun or its power cord on your fuel injector lines and bending/breaking them.  But some are potentially catastrophic, like the heating element or the temp controller malfunctioning, and starting a fire while unsupervised.  When it comes to inexpensive DIY heating solutions, there just a lot of good, common-sense risk mitigation in keeping the thing that is generating the heat outside the engine compartment.

[RobertGary1]

I would worry about such a narrow concentrated heat application. Those things put out a lot of heat but probably not enough to warm the engine. But enough to fry wiring and melt hoses.

 

-Robert

[RLCarter]

Too hot in a concentrated area..... better luck painting your house with a Q-tip 

[jaylw314]

Guys, EVERY electrical appliance is rated for up to 1500W on an household outlet.  That means all your space heaters, heat guns, Tanis heaters and so on produce only that much heat.  As long as you insulate the cowl enough, they'll all reach the same engine temp (although the hottest part might be different).

I have done the heat gun thing--just rigged it up to a 4" flexible heater duct and fed it up one of the cowl ducts, then covered the cowling with moving blankets.  I left it running for a couple hours (I didn't want to leave a heat gun on overnight), and it worked...okay (got the CHT's up to about 40 degF on a 30 degF day).  the opening of the heating duct is big enough that even if you stick the heat gun in, it sucks in cool air around it so the air that comes out is only warm, not enough to cause damage anything in the plane (although hot enough to burn your hand, so be careful).

Edited November 5, 2020 by jaylw314

[Ragsf15e]

1 hour ago, jaylw314 said:

Guys, EVERY electrical appliance is rated for up to 1500W on an household outlet.  That means all your space heaters, heat guns, Tanis heaters and so on produce only that much heat.  As long as you insulate the cowl enough, they'll all reach the same engine temp (although the hottest part might be different).

I have done the heat gun thing--just rigged it up to a 4" flexible heater duct and fed it up one of the cowl ducts, then covered the cowling with moving blankets.  I left it running for a couple hours (I didn't want to leave a heat gun on overnight), and it worked...okay (got the CHT's up to about 40 degF on a 30 degF day).  the opening of the heating duct is big enough that even if you stick the heat gun in, it sucks in cool air around it so the air that comes out is only warm, not enough to cause damage anything in the plane (although hot enough to burn your hand, so be careful).

Yeah, I guess the key is diffusing the heat over an area and over time.  I.e. putting it through a 4” duct through the cowl flaps for 4 hours vs shooting a heat gun directly at a part of the engine for a “quick” preheat.  Maybe the actual amount of heat is the same, but warming the entire compartment over several hours is probably more effective and safer.  

[EricJ]

A soldering iron is only about 50W, but it puts it all in a small region.    That's the problem with a heat gun, its purpose is to put more heat in less air than a typical heater does, so the output temperature is typically a lot higher.

That said, 500W isn't that much for heating air, but how concentrated it is and what it's hitting before it gets a chance to diffuse and cool a little bit makes a difference.

 

[jaylw314]

Just now, EricJ said:

A soldering iron is only about 50W, but it puts it all in a small region.    That's the problem with a heat gun, its purpose is to put more heat in less air than a typical heater does, so the output temperature is typically a lot higher.

That said, 500W isn't that much for heating air, but how concentrated it is and what it's hitting before it gets a chance to diffuse and cool a little bit makes a difference.

 

True, I should point out that I put the heat gun on the HI fan setting to maximize the amount of air going through the gun.  heck, you could probably just rig a stand to blow the hot air into the cowl flap from a couple feet away and you'd be okay (although you'd want to be sure the rig was secure for obvious safety reasons).

[cferr59]

If I was going to rig up a preheater, I would use something like this with ducting to direct the heat into the cowl.  I had done this for my previous 152, but at the time no battery powered heaters were available so I used an inverter.  Not sure where you are, but if it is regularly cold and you can power it, a proper preheater is worth the trouble to install.  One of the first things I did to my Mooney was install a Reiff Turbo system.  I don't see a 500 watt air powered heater doing much of anything unless it is left on for a long period of time.

 

 

[carusoam]

Heat gun that comes with paint removal scraping tools... interesting...

1) If you have electricity... there are so many options...

2) Out at a tie-down... there is so little electricity near by...

3) Rieff and Tanis have done a really good job of delivering real solutions to engine heating....

4) Engine fires, and melting paint can be real challenges for engine heating...

5) Using a duct can help get the warm air in place... and keep the hot air at bay...

6) Find the portable generator thread to support this...

PP summary, pro-reinvent the wheel.... 

Best regards,

-a-

[PT20J]

You know, maybe it's just me, but a few hundred bucks to do it right and safely seems miniscule compared to the risk of damaging an airframe or engine worth tens of thousands.

[Guest]

We heat our daughter’s Cessna 150 with a 60 watt light bulb in a trouble light and a pair of old sleeping bags on the cowl. We slip the light in the bottom of the cowl opening.

Cheap and simple