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  #1  
Old 07-28-2020, 07:40 PM
ethand ethand is offline
 
Join Date: Mar 2013
Location: San Diego
Posts: 199
Default How To Cover the Heat Muff Exit

Chasing a fuel pressure issue on my RV-10 and one of the ideas to start from this thread is to remove the tube from the heat muff exit to the cabin heat boxes. Based on some testing and symptoms I would like to start there.

https://vansairforce.com/community/s...d.php?t=168359

Question is how do I safely cover the heat muff exits? AL tape? Stainless cap?

Thank you

Ethan
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  #2  
Old 07-28-2020, 07:48 PM
David Paule David Paule is offline
 
Join Date: Dec 2009
Location: Boulder, CO
Posts: 4,761
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If you leave the muffs on but block the air flow through them, there's a chance that you could damage them, possibly severely. That flow keeps them from overheating.

Dave
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  #3  
Old 07-28-2020, 09:36 PM
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Plummit Plummit is offline
 
Join Date: Apr 2010
Location: SoCal
Posts: 1,270
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Or you could take cold air to one of the cabin heat flaps. Here's the link:

https://www.vansaircraft.com/service...n-tunnel-temp/

-Marc
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  #4  
Old 07-29-2020, 04:57 AM
flysrv10 flysrv10 is offline
 
Join Date: Jan 2010
Location: Florida
Posts: 337
Default

Quote:
Originally Posted by ethand View Post
Chasing a fuel pressure issue on my RV-10 and one of the ideas to start from this thread is to remove the tube from the heat muff exit to the cabin heat boxes. Based on some testing and symptoms I would like to start there.

https://vansairforce.com/community/s...d.php?t=168359

Question is how do I safely cover the heat muff exits? AL tape? Stainless cap?

Thank you

Ethan
I made two circular disk that fit into the scat tubing. I install them in the summer to block all air into the cabin and prevent hot air hitting the firewall. My disks are aluminum and are inserted at the baffles. They stay in place due to tight fit. I put a tab on the disks so I can retrieve them with a needle nose.

Several seasons and no ill effects on heat muffs or exhaust pipes. The tunnel stays cool to touch.
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  #5  
Old 07-29-2020, 07:12 AM
lr172 lr172 is online now
 
Join Date: Oct 2013
Location: Schaumburg, IL
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Quote:
Originally Posted by flysrv10 View Post
I made two circular disk that fit into the scat tubing. I install them in the summer to block all air into the cabin and prevent hot air hitting the firewall. My disks are aluminum and are inserted at the baffles. They stay in place due to tight fit. I put a tab on the disks so I can retrieve them with a needle nose.

Several seasons and no ill effects on heat muffs or exhaust pipes. The tunnel stays cool to touch.
I would talk to clint over at Vetterman. He seems pretty confident that this will cause long term issues/problems. Not saying he can't be wrong, but that is his profession.

Larry
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  #6  
Old 07-29-2020, 07:30 AM
flysrv10 flysrv10 is offline
 
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Location: Florida
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Quote:
Originally Posted by lr172 View Post
I would talk to clint over at Vetterman. He seems pretty confident that this will cause long term issues/problems. Not saying he can't be wrong, but that is his profession.

Larry
I talked to Vetterman before I blocked the scats. He did not see any issues with doing it. Let me know if you get a different answer.
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  #7  
Old 07-30-2020, 06:15 AM
Scott Hersha Scott Hersha is offline
 
Join Date: Jan 2005
Location: Cincinnati, OH
Posts: 1,808
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You might be talking about two separate things here. Blocking off air from circulating through a heat muff on the exhaust pipe can damage the exhaust pipe - so Iíve been told. Blocking off scat air at the firewall Heat valve by removing the scat tube and covering the opening at the firewall may help with cabin heat gain. You need to allow air to travel through the muff, or just remove the heat muff, temporarily. I did it that way on my RV8, and it seemed to help with cabin temp.
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  #8  
Old 07-30-2020, 06:48 AM
lr172 lr172 is online now
 
Join Date: Oct 2013
Location: Schaumburg, IL
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Quote:
Originally Posted by flysrv10 View Post
I talked to Vetterman before I blocked the scats. He did not see any issues with doing it. Let me know if you get a different answer.
Maybe a communications issue. I believe that Larry Vetterman has posted this concern a few times on this forum. This assumes that I understood your post to mean that you are blocking air at the baffling and therefore have 0 flow through the muffler.

A safer way is to move the scat from the heat valve on the firewall and put it near the cowl exit.

Larry
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  #9  
Old 07-30-2020, 07:05 AM
flysrv10 flysrv10 is offline
 
Join Date: Jan 2010
Location: Florida
Posts: 337
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Quote:
Originally Posted by lr172 View Post
Maybe a communications issue. I believe that Larry Vetterman has posted this concern a few times on this forum. This assumes that I understood your post to mean that you are blocking air at the baffling and therefore have 0 flow through the muffler.

A safer way is to move the scat from the heat valve on the firewall and put it near the cowl exit.

Larry
A quick search and I cold not find his comments but I did not do an exhaustive search.

However, I have been doing this for several seasons without any ill effects. So in practice, at least for me, it has worked very well.

You have an alternative by removing the tubing from the valves. I wanted to have max cooling so I opted for my solution.
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  #10  
Old 07-30-2020, 08:13 AM
ethand ethand is offline
 
Join Date: Mar 2013
Location: San Diego
Posts: 199
Default Talked to Clint

Just got off the phone with Clint at Vetterman and he suggested blocking the exit of the shroud would cause issues within a 100 hours or so unless cooling was maintained.

I guess I will work on a shroud or dumping the air out the bottom of the cowl.

E
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