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Hot Wire Grid for Carb Heat

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perfeng(at)3rivers.net
Guest

Posted: Mon Jan 01, 2007 11:09 am Post subject: Hot Wire Grid for Carb Heat

Hello All,

 Does anyone on the list know of a 12 VDC / < 20  amp powered "hot wire grid" heater that is roughly 2" - 3"  dia.?

 My question comes from trying to find a suitable  way to heat intake air other than byway of a carb heat box due to space  limitations.  The thought is to also maintain filtered air all  the time by placing this "grid" inline between the filter and carb  inlet.  I know of several automotive/diesel applications that meet the size  requirements but, their grids draw way beyond the capability of the average  aircraft electrical system.

 Any thoughts or suggestions? 

  

 Jim D.  RV-7a

   [quote][b]

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nuckollsr(at)cox.net
Guest

Posted: Mon Jan 01, 2007 11:39 am Post subject: Hot Wire Grid for Carb Heat

At 12:10 PM 1/1/2007 -0700, you wrote:



 	  Quote: 	
		  Hello All,

Does anyone on the list know of a 12 VDC / < 20 amp powered "hot wire 

grid" heater that is roughly 2" - 3" dia.?

My question comes from trying to find a suitable way to heat intake air 

other than byway of a carb heat box due to space limitations.  The thought 

is to also maintain filtered air all the time by placing this "grid" 

inline between the filter and carb inlet.  I know of several 

automotive/diesel applications that meet the size requirements but, their 

grids draw way beyond the capability of the average aircraft electrical system.

Any thoughts or suggestions?


	


   You're right about the power needed. When you consider the

   temperature rise you're attempting to place on a rather

   large mass of air, the energy requirements are significant

   and a 240 watt heater is not going to cut it. This is

   exactly why the heaters you've noted seem to be such

   "power hogs" . . . BTUs off the exhaust stacks are "free",

   while BTUs off the alternator/battery system are exceedingly

   expensive.



   Bob . . .



      ---------------------------------------------------------

      < What is so wonderful about scientific truth...is that >

      < the authority which determines whether there can be   >

      < debate or not does not reside in some fraternity of   >

      < scientists; nor is it divine. The authority rests     >

      < with experiment.                                      >

      <                            --Lawrence M. Krauss       >

      ---------------------------------------------------------

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sportav8r(at)gmail.com
Guest

Posted: Mon Jan 01, 2007 4:23 pm Post subject: Hot Wire Grid for Carb Heat

Lots of RV's scavenge the heat in the lower half of the cowl for carb

heat, without any heat muffs, just what comes off  the cylinder

fins... seems to work okay - zero extra space required.



-Bill B



On 1/1/07, Robert L. Nuckolls, III <nuckollsr(at)cox.net> wrote:

 	  Quote: 	
		   



 At 12:10 PM 1/1/2007 -0700, you wrote:



 >Hello All,

 >Does anyone on the list know of a 12 VDC / < 20 amp powered "hot wire

 >grid" heater that is roughly 2" - 3" dia.?

 >My question comes from trying to find a suitable way to heat intake air

 >other than byway of a carb heat box due to space limitations.  The thought

 >is to also maintain filtered air all the time by placing this "grid"

 >inline between the filter and carb inlet.  I know of several

 >automotive/diesel applications that meet the size requirements but, their

 >grids draw way beyond the capability of the average aircraft electrical system.

 >Any thoughts or suggestions?



    You're right about the power needed. When you consider the

    temperature rise you're attempting to place on a rather

    large mass of air, the energy requirements are significant

    and a 240 watt heater is not going to cut it. This is

    exactly why the heaters you've noted seem to be such

    "power hogs" . . . BTUs off the exhaust stacks are "free",

    while BTUs off the alternator/battery system are exceedingly

    expensive.



    Bob . . .



       ---------------------------------------------------------

       < What is so wonderful about scientific truth...is that >

       < the authority which determines whether there can be   >

       < debate or not does not reside in some fraternity of   >

       < scientists; nor is it divine. The authority rests     >

       < with experiment.                                      >

       <                            --Lawrence M. Krauss       >

       ---------------------------------------------------------

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JimT

Joined: 27 Feb 2006
Posts: 22
Location: Auburn, ME

Posted: Mon Jan 01, 2007 4:54 pm Post subject: Hot Wire Grid for Carb Heat

Okay here goes a hijack attempt.  

  

 I am  concerned about the same problem in a rotax 912S.  I found  this source

 http://www.ulparts.com/SearchResult.aspx?CategoryID=94

  

 I spoke with the dealer.  They say the only complaint they have is  about the fragility of the wires for the heating element.   No  complaints about effectiveness.  ( I am "told" the 912 series of engines is  not particularly prone to  iced carbs anyway).

  

 My thought was exactly  Bob's response.  I would think the  current draw is simply not enough to keep the carb body  above  freezing.   what would be the expected heat requirement?   (  There that part at least is a general question).  Any other experience with  this device?

  

 JimT

  [quote][b]

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echristley(at)nc.rr.com
Guest

Posted: Mon Jan 01, 2007 5:14 pm Post subject: Hot Wire Grid for Carb Heat

Robert L. Nuckolls, III wrote:

 	  Quote: 	

 <nuckollsr(at)cox.net>

 At 12:10 PM 1/1/2007 -0700, you wrote:

> Hello All,

> Does anyone on the list know of a 12 VDC / < 20 amp powered "hot wire 

> grid" heater that is roughly 2" - 3" dia.?

> My question comes from trying to find a suitable way to heat intake 

> air other than byway of a carb heat box due to space limitations.  

> The thought is to also maintain filtered air all the time by placing 

> this "grid" inline between the filter and carb inlet.  I know of 

> several automotive/diesel applications that meet the size 

> requirements but, their grids draw way beyond the capability of the 

> average aircraft electrical system.

> Any thoughts or suggestions?

   You're right about the power needed. When you consider the

   temperature rise you're attempting to place on a rather

   large mass of air, the energy requirements are significant

   and a 240 watt heater is not going to cut it. This is

   exactly why the heaters you've noted seem to be such

   "power hogs" . . . BTUs off the exhaust stacks are "free",

   while BTUs off the alternator/battery system are exceedingly

   expensive.

   Bob . . .

Jim, an alternative for you might be heat pipes.  I have a friend that 

has worked on some research projects where they were instrumental in 

transferring heat in a compact area.

You fill a tube with a small amount of coolant, and seal both ends.  He 

used copper and sealed with solder.  Wrap the bottom around the muffler, 

and stick the top in the intake.

  The heat will boil the coolant (water will probably suffice in this 

case), which will rise up the tube.  It will cool in the intake and run 

back down, to be boiled again.  I won't work if you're flying inverted 

for extended periods, but a wide range of positive gradients will work 

effectively.  Mark got at least some effectiveness if the cool end was 

even just high enough for the tip to be above the fluid level.  He also 

found that a wide range of fluid levels would be effective.

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rv9jim(at)juno.com
Guest

Posted: Tue Jan 02, 2007 7:07 am Post subject: Hot Wire Grid for Carb Heat

Jim,

        I had a 912S for several years.  The engine can get carb ice. 

There is a water heated jacket that attaches to the carburetor

immediately down stream of the carb.  It actually attaches to the carb. 

This jacket keeps the throttle plate from icing up.  I think Rotax sell

it.  It was originally designed and available from England.  That unit

(2) will keep ice from forming period.  You hook it up and forget it. 

Forget the on / of valve and temp indicator as it is all stuff not

needed.  It operates all the time the engine is running and producing hot

water.  I added it to my Rotax to avoid having another control to mess

with and have ice build up and give me to much stress.  Its worth the

added cost.



Jim Nelson

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