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-   -   tunnel heat (https://vansairforce.net/community/showthread.php?t=70841)

kenmorris 04-11-2011 04:27 PM

tunnel heat
 
Has the tunnel heat problems been resolved?

RV10Rob 04-11-2011 04:46 PM

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

Ron B. 04-11-2011 06:25 PM

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.
Ron

Pat Stewart 04-17-2011 01:11 PM

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.

Pat

vic syracuse 04-17-2011 01:48 PM

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

bcondrey 04-17-2011 01:53 PM

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.

Bob

Pat Stewart 04-17-2011 01:59 PM

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.

Pat

N427EF 04-17-2011 02:36 PM

Heat Muff Removal?
 
If you remove the air supply to the heat muff and remove the shroud will the muffler part still suffer heat damage?
We really don't need heat here 9 month out of the year and keeping the air in the plenum on the top would do more good than running it through
the heat muff.
Just curious.

vic syracuse 04-17-2011 04:34 PM

Just run the scat tube out the bottom of the cowling instead of connecting it up to the heat boxes on the firewall. Bob's suggestions are right on the mark for those who are still building. It's a little tough to get in there and change the boxes after the engine is installed and everything is plumbed.
For those of you who don't think you need the heat because you live in hot climates, I would hint that you might not be getting the most out of your RV-10 in flight. In the summer time, the performance of the 10 allows you to climb to 10k'-15k' quite rapidly. It typically gets you out of the summer time haze and into smoother, more comfortable air. And then sometimes you will want that heat, even in the summertime, especially if there is a high overcast blocking the sun.

Vic

Geico266 04-17-2011 04:58 PM

I pulled the heat shrouds on my -10 in the spring and put them back on in the fall. In the summer I route the fresh air scat tube to better cool the fuel pump. The "mufflers" are fine.

I have two heat muffs, one for the front and one for the rear, but having them boh hooked up and open will drive you out of the plane 30f temps. I now have plumbed one heat shroud for both front and rear and have flown in 10f temps in light jackets.

I agree with Vic and for those building a -10 an O2 system is a must. The airspace between 12k and 18k is smoother, and a "road less traveled"

Hope this helps.


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