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  #1  
Old 12-07-2009, 05:18 PM
the_other_dougreeves the_other_dougreeves is offline
 
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Location: Dallas, TX (ADS)
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Default Low budget preheat

Doug had a comment on the front page today about his hairdryer preheating system and that it worked, sort of. Turns out a hairdryer works for the 912 series as well, probably down to around 30F.

If you're too lazy / don't want to install a preheater, you can use a hairdryer in the cooling air scoop. I would recommend only the high-flow, low heat setting on the dryer to try and keep air temps from getting too hot and scorching anything; the dryer is probably putting out 400W or so. It won't heat the oil tank much, but it will get the cylinders and battery warmish, and that will help prevent kickback when starting (kickback is very bad for the gearbox). Mine started easily after 30-40 minutes of preheat - enough time to preflight the airplane and enjoy a cup of coffee with my hangar neighbors. This probably works well for those of us who don't often get temps below freezing.



Be sure to remove the hairdryer before engine start.

If you DO want to install a preheater, both Reiff and Tanis make 912-specific systems. The Reiff is a lot cheaper than the Tanis. Reiff is only a pad on the bottom of the crank and a band around the oil tank. Tanis uses heating elements in bolts that you replace on the inlet manifold and a strip heater on the oil tank. The Tanis probably works better in harsh conditions, but I don't want to fly in harsh conditions - this pilot probably isn't hearty enough to go flying in sub-zero temps (Yes, I know I'm going to take flak from the Yankees on this one).

TODR
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  #2  
Old 12-18-2009, 12:38 PM
Reiff Preheat Systems Reiff Preheat Systems is offline
 
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Location: Ft. Atkinson, WI
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Default

If you don't mind a suggestion... I know there are a lot of ways people preheat their airplanes but I'd suggest that consideration be given to the intended use of the device. In the case of a hair dyer, the designers intended it would be used for maybe a couple of minutes at a time, once per day, and last maybe 5 yrs. That's a design lifespan of perhaps 50 hrs. If you run it continuously for hours at a time as an engine preheater it probably won't hold up well, and when it fails I'd want to be there, especially if it's hanging on the airplane. I'm not saying don't use it... just stick around and keep an eye on it. Don't leave it run unattended all night or anything like that. If that's what you want to do I suggest it would be safer to get a heater that's designed for continuous use, like a space heater or an industrial grade heat gun.

Also, anything you can do to seal and insulate the engine compartment to prevent leakage of the warm air will improve the effectiveness of whatever heater you use. A moving blanket over the nose helps a lot.

As far as what works better in harsh conditions, that's a matter of watts and heating time, not name and price.
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  #3  
Old 12-18-2009, 01:19 PM
the_other_dougreeves the_other_dougreeves is offline
 
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Location: Dallas, TX (ADS)
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Quote:
Originally Posted by Reiff Preheat Systems View Post
I'm not saying don't use it... just stick around and keep an eye on it. Don't leave it run unattended all night or anything like that. If that's what you want to do I suggest it would be safer to get a heater that's designed for continuous use, like a space heater or an industrial grade heat gun.
Suggestions are good.

My typical use is (1) stop for a cup of coffee, (2) arrive at hangar and plug in HPS (Hairdryer Preheat System TM ), (3) drink coffee, preflight, do small chores that you've put off, chat with hangar neighbors, (4) 45 minutes later, start engine. I would not recommend operating this system unattended.

TODR
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  #4  
Old 12-18-2009, 01:38 PM
JBPILOT JBPILOT is offline
 
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Location: Jesup, Iowa
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Default Another suggestion

Put a packing blacket over the entire cowl during heating. It will warm better that way. Cool air will come out the bottom, so nothing else to do. I plan to make a heavy foam ring so that the hair-dryer stays in place nicely. If it is below 50 degrees, the hair-dryer will not get overly warm anyway. Cheap and fast way to warm it some. If you warm it 20 degrees, it will help.

John Bender
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  #5  
Old 12-18-2009, 01:40 PM
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Sheldon Sheldon is offline
 
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Location: Concho, Arizona
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I use the hair dryer system too... 2 of them.. but both have a clothes dryer type hose connected to the snout... about 3 feet long... I put one on the floor under the cowl and stick the hose up into the cowl by the exaust pipes..and sit the other dryer on a stool in front of the plane and stick the hose into one of the air inlets.. plugging the other... then after awhile, I switch inlets... With a heavy blanket on top of the cowl, takes about 45 minutes to increase the oil temp 35 degrees higher that at start (gauge reading).. I just get there early and do preflight and otherthings while it's heating up... Works for me...
Sheldon
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  #6  
Old 12-18-2009, 02:46 PM
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pierre smith pierre smith is offline
 
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Location: Louisville, Ga
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Default The main point of heating the oil....

...is to ensure quick starts and good cam lobe/lifter/cylinder splash lubrication at startup. The hair dryer system does not address this problem...you still have thick/non-splash oil, only easy starting because of the warm cylinders.

Compared to the price of engines and airplanes, the Reiff system is a bargain.

Best,
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  #7  
Old 12-18-2009, 05:32 PM
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Geico266 Geico266 is offline
 
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This is my BIG hair dryer. It fits under the cowl and blows warm air where the exhaust pipes are. I leave it on 24/7, keeps the oil 50F reguardless of OATs. I think this milkhouse heater was $20 + $15 for the duct work. Works on any RV.




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Last edited by Geico266 : 12-18-2009 at 05:41 PM.
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  #8  
Old 12-18-2009, 06:17 PM
JohnF JohnF is offline
 
Join Date: Jan 2005
Posts: 458
Default Engine Heater

I use a small space heater modified with two clothes dryer aluminum flex hoses that I push into the RV6A air intake, and also plug in a Reiff 300-watt heater pad that was 'glued' onto the bottom of the oil pan in my o320Lycoming ...after an hour the oil temp is in the mid-50s or more even in zero temps...easy starts, and the heater at Wal Mart is about $25 plus a few more dollars for the dryer ducts...the oil pan heater is more expensive but worth it IMHO - I put both on a timer to turn on about an hour before I expect to arrive at the hangar.

John
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  #9  
Old 12-18-2009, 06:30 PM
rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
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Quote:
Originally Posted by pierre smith View Post
...is to ensure quick starts and good cam lobe/lifter/cylinder splash lubrication at startup. The hair dryer system does not address this problem...you still have thick/non-splash oil, only easy starting because of the warm cylinders.

Compared to the price of engines and airplanes, the Reiff system is a bargain.

Best,
I agree with Pierre...but only partially.
I think anything you can do that raises the oil temp any amount above what it would have been, helps.
I preheat my O-360 with a hair drier blowing into the air exit of the bottom of the cowl (clamped to on one of the exhaust pipes with a spring clamp).
With a Lycoming this puts the air blowing on the bottom of the oil sump.
I throw a blanket over the cowling and have plugs for the air inlets.

I tend to do it anytime the temp hits about 40 F. or lower (though it is rare for it to get much lower than 30 F.) This might not do much at temps near zero, but it makes a very measurable difference in how fast my oil pressure comes up compared to doing nothing at the same temp.

With a Rotax it probably would be better if the air could be directed onto the oil tank, but I think warming up the engine compartment (which will start to warm up the oil tank) is still much better than doing nothing.
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  #10  
Old 12-18-2009, 06:40 PM
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scard scard is offline
 
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Location: Cedar Park, TX
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Quote:
Originally Posted by Geico266 View Post
This is my BIG hair dryer. It fits under the cowl and blows warm air where the exhaust pipes are. I leave it on 24/7, keeps the oil 50F reguardless of OATs. I think this milkhouse heater was $20 + $15 for the duct work. Works on any RV.




Patent Pending
Now we are talking. I see one of those in my near future. My logistics officer has been engaged for the parts and assembly process. Thanks for the picture, I like.
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