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Old 04-11-2011, 04:27 PM
kenmorris kenmorris is offline
Join Date: Mar 2005
Location: McKinney, Texas
Posts: 65
Default tunnel heat

Has the tunnel heat problems been resolved?
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Old 04-11-2011, 04:46 PM
RV10Rob's Avatar
RV10Rob RV10Rob is offline
Join Date: Mar 2007
Location: Woodinville, WA
Posts: 534

Mine doesn't seem hot. My exhaust pipes (stock Vetterman delivered in 2009) are really long, so that may be the reason why. I think (but am not sure) that these are longer than on the older exhausts.

Rob Kochman
RV-10, Flying as of March 2011 (blog)
Paine Field (KPAE)
EAA Chapter 1440
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Old 04-11-2011, 06:25 PM
Ron B. Ron B. is offline
Join Date: Nov 2007
Location: Yarmouth, Nova Scotia
Posts: 2,694

Our tunnel has fabric from Flightline covering it. The only metal we can touch is the Andair fuel valve. The handle is quite warm but certainly not hot. What is the standard for hot? What should we be checking for? We have the Sounddown insulation in the tunnel floor, it's about one inch thick. I moved our fuel system components up about an inch from their standard location to accomodate the insulation.
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Old 04-17-2011, 01:11 PM
Pat Stewart Pat Stewart is offline
Join Date: Jan 2005
Location: Granbury Texas
Posts: 1,136
Default Tunnel Heat

I have a center console and mine does get warm. My throttle quad is mounted in the center console and was very warm to the touch so I am sure everything else in the tunnel is warm. This weekend I removed the forward fresh air scat tube from the left heater muff and plumbed it directly into the tunnel. This appeared to help. I still have aft heat and when the day comes that I need heat in Florida/cross country I will tee it and hook back up the forward heat.

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Old 04-17-2011, 01:48 PM
vic syracuse vic syracuse is offline
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Join Date: May 2005
Location: Locust Grove, GA
Posts: 2,728

Pat, those mufflers NEED airflow thru them or you are going to burn them up. The fix is to put a "Y" into the scat tube off of the back baffling behind Cylinder 5, and run the output to both the right hand muffler and the firewall tunnel area.

Vic Syracuse

Built RV-4, RV-6, 2-RV-10's, RV-7A, RV-8, Prescott Pusher, Kitfox Model II, Kitfox Speedster, Kitfox 7 Super Sport, Just Superstol, DAR, A&P/IA, EAA Tech Counselor/Flight Advisor, CFII-ASMEL/ASES/RW
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Old 04-17-2011, 01:53 PM
bcondrey bcondrey is offline
Join Date: Jan 2005
Location: Bellevue, NE
Posts: 554

the tunnel heat issue is resolved easily by:
1) putting some sort of insulation between the heat valves and firewall. Best would be a piece of silicone baffle material - this largely prevents the heat blowing on the valves from conducting to the cabin side (tunnel) and therefore heating up the tunnel

and 2) swapping to the stainless heat valves which have much better sealing than the stock aluminum versions.

If you elect to stay with the stock aluminum heat valves you can get probably fix most of the issue with generous application of red RTV in strategic locations on the valves. First, air gets under the hinged side of the flapper because of the play in the hinges. Make a little RTV air dam so the air isn't blowing directly on the hinged edge of the flapper. You might also consider a light coating so the flapper seals better when shut. You can see the issue by simply hooking up the blower port on a shop vac to the engine side heat valve air port and watching what happens.

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Old 04-17-2011, 01:59 PM
Pat Stewart Pat Stewart is offline
Join Date: Jan 2005
Location: Granbury Texas
Posts: 1,136
Default Tunnel Heat

Thanks Vic,

Do you then just let the heat muff exhaust inside the cowling. I had considered that however that would put the heat muff exhaust just forward of the oil cooler.

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Old 04-18-2011, 08:12 AM
Randy Means Randy Means is offline
Join Date: Apr 2008
Location: Cocoa Florida
Posts: 43
Question Tunnel Heat

Perfect timing to discuss too much heat in the center tunnel area. My fuel selector doesn't get too hot but the sheet metal is very warm. My concern is that it could damage the wires I have routed there. It appears that the solution would be to cover the floor of the tunnel with a heat refletive material. My concern is damage to the wires.
Randy Means
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Old 04-18-2011, 10:27 AM
Pat Stewart Pat Stewart is offline
Join Date: Jan 2005
Location: Granbury Texas
Posts: 1,136
Default Heat

The floor of my tunnel is insulated however the standard heat boxes are mounted to the firewall with no insulation between them and the firewall.

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Old 04-18-2011, 08:26 PM
rmcgann rmcgann is offline
Join Date: Jan 2006
Posts: 52
Default Tunnel Heat

I have cool mat insulation on the firewall and the floor of the tunnel. My tunnel does get very warm to hot (my wife can't place her leg against it, but I have no trouble.) Seems to be very much affected by outside air temperature (ie more noticeable in the summer at low altitude - certainly more comfortable with cooler OAT).

My standard aluminium heat vents are mounted directly to the firewall- I will try insulating them and see what happens.

VH-XRM flying in Oz
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