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Dual mufflers - Dual heatbox

pgroell

pgroell

Well Known Member
Friend
Hi all,
In my RV-7A, I will be installing a Vetterman exhaust with dual mufflers. The mufflers must be ventilated at all time, so I will have to heat sources.
I'm trying to install two heat boxes, but don't want to get cornered if the second heat box gets in the way of some other item on the firewall.
My first heatbox will be at the standard place, the picture below shows where I intend to install the second one.
Is that possible at all? If not I'll go with one heatbox only and vent the second muffler's output overboard.
Thanks for your input.

Heatbox2.jpg
 
Hmmm...

You know, these things put out so little heat that I think you will be better off plumbing the muffs in series and just using the one heat box on the firewall. I mean it is a firewall, why cut more holes into it? Also, with two heatboxes you will need two cables and the attendant space on the panel.

Plumb it in series.

If you really want two heatboxes then I would wonder if you are going to have a constant speed prop and which engine you plan to use because you have to consider the governor cables...

Hans
 
N941WR said:
If you are looking for more heat, get some exhaust heat wrap and wrap just the heater muff.
Click to expand...

I dont know if I would do that--------call Vetterman for more info, but basically you can ruin the exhaust system with the heat wrap. Just the Muffler----?? Maybe it is OK, but not the pipes for sure.
 
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Keep the air flowing, and keep the shroud on

Just as an information point..... The muffler will create more heat than a heat muff. I was told to make sure and always have the shrouds on the mufflers, as well as air flowing through them. If not, the mufflers will overheat, and deteriorate much faster.
 
Mufflers

Thanks for those answers,
and just to clarify a bit.
I'm not looking for more or less heat it's just that I'm told the mufflers (used to lower the noise) are outputting a lot of heat (much more than the heater muffs used on the standard Vetterman exhaust, that's why they have to be ventilated all the time).
I think I can use the heat, it can be pretty cold in winter here (northern part of France).
 
Mike S said:
N941WR said:
If you are looking for more heat, get some exhaust heat wrap and wrap just the heater muff.
Click to expand...

I dont know if I would do that--------call Vetterman for more info, but basically you can ruin the exhaust system with the heat wrap. Just the Muffler----?? Maybe it is OK, but not the pipes for sure.
Click to expand...
Mike,

Note, I said to put the wrap on the heat muff only, not the exahust. You are correct, Vetterman does not recommend wrapping the exhaust.

That will keep the hot air in the heat muff, thus producing more warm air for the cabin heat.

Also, I would not recommend wrapping the muffler either.
 
Muff-----muffler:confused::confused:

OOPS, my mistake. I need to read a bit slower.

On my plane the heat muffs are wrapped around the mufflers.
 
any pictures of dual heat boxes in a 7 or 9

This is an old thread - but I'd like to revive it if possible.... Does anyone have any pictures of dual heat boxes in a 7 or 9?

I'm planning a Vetterman muffler exhaust and after talking to Larry I want two heat boxes. Larry told me the mufflers run HOT and you cannot plumb them in series. They must have airflow through at all times. He said most people hook one muffler o a heat box and dump the heat from the other

I'd like to have each muffler feed its own heat box (probably a Robbins box). Where should I put the 2nd box? Anybody have any pictures?

This should provide lots of heat, and combined with electric seats, should increase the spousal acceptance factor. Dual controls (his/hers) are a benefit. That might be why I'd like to locate the 2nd box on the right side.

My backup plan is a single box in the stock location, with a Y on the input side to take heat from both mufflers.

Thanks!
 
Dave and others...

Larry wrote me a note this morning and asked that I post it to this thread:

Larry Vetterman said:
BIll I just read the thread on mufflers etc. There is confusion and mis information being published. The muffler system is not the same as a standard heat muff. They give out at least twice as much heat so dual systems are an accepted practice. Do not plumb them in series as one uninformed builder suggested. I ask that all questions about mufflers and installation of them be directed to me. Feel free to publish this. Larry
Click to expand...

Larry is a great guy and has lots of knowledge about exhausts, heat muffs, mufflers, speed mods, etc. Give him a call, if you have any questions.
 
dual heat boxes

Thanks Bill (and Larry) - maybe I wasn't clear, but I'm trying to follow Larry's advice.

I want to have a dual system, where each muffler feeds its own heatbox. Nothing in series.

I'm looking for someone else who has done this on a 7 or 9, so I can see where to put the heat boxes
 
On my -10.....

...the two triangular boxes are mounted on the firewall, just below the oil filter recess and almost touch each other. The operating cables criss-cross each other.....unfortunately my camera is in my wife's car....

I can assure you that with dual mufflers, there's a ton of heat in my -10.

Best,
 
I'm a bit confused. If you need constant air flow through the muffler, then one could not use the triangler box (VENT TG-10), and would need to use the square box with a by-pass port (VENT DL-01).
 
#N72CR said:
I'm a bit confused. If you need constant air flow through the muffler, then one could not use the triangler box (VENT TG-10), and would need to use the square box with a by-pass port (VENT DL-01).
Click to expand...
Chris,

The triangler box dumps the air when closed, allowing air to pass through the muffler and keeping it from burning up.
 
Dual Heat Muffs

Pascal,

I have an RV-8 with Vetterman mufflers and dual heat boxes. I installed one heat box per plans which provides hot air to the feet area. The second heat box was installed on the RHS of the firewall and then plumbed to a large eyeball vent that is easily accessible in flight. This will allow you to direct hot air to the upper areas.

Good Luck.

Mike
 
drill_and_buck said:
Pascal,

I have an RV-8 with Vetterman mufflers and dual heat boxes. I installed one heat box per plans which provides hot air to the feet area. The second heat box was installed on the RHS of the firewall and then plumbed to a large eyeball vent that is easily accessible in flight. This will allow you to direct hot air to the upper areas.

Good Luck.

Mike
Click to expand...

Mike,
Could you post a few photos of your system?
Charlie Kuss
 
Dual Heat Muffs

Two heat boxes and view of Vetterman muffler/heat muff. The heat box on the lower right of the picture vents directly to the area behind the rudder pedals. The other heat box is plumbed to an eyeball vent.

rv8dualheatboxes.jpg


Eyeball vent to direct heat. Two heat box control cables on gear leg tower.

hotairvent.jpg
 
I've got some pictures of what I did on my RV-7A for dual heat boxes. I mounted Van's center one in the traditional position, but with the opening to the mufff facing outward so it was asily attached with hose to the left exhaust pipe muff.
The second heat box was mounted onto the firewall high (above the rudderr peddles) on the right side to enable easy connection to the right heat muff. this was a straight through heat box, modifided to have a straight through the firewall push/pull control cable. Email me for the pictures of this modified part.
The right side heat box then uses a SCAT tub to channel the air to the passenger and pilot lap areas...
 
2 muffler

I have 2 muffler with 2 heat muff on a rv7 . The plane is hot enough for the minus 30 of canada. I have put a T for the 2 heat muff to go to one heat box. I will tru to see if i still have some picture of the construction

Lan Vinh Do
 
Mike,

I was just asking Vetterman about how to modify the 8A cowl to accomodate a dual muffler exhaust. He suggested I ask for photos of such modifications on VAF. Have you got a collection of such that you could point me to?

Cheers,
John
 
Mike S said:
Muff-----muffler:confused::confused:

OOPS, my mistake. I need to read a bit slower.

On my plane the heat muffs are wrapped around the mufflers.
Click to expand...
Heater muffs on the muffler? is that custom by you? Do you have pictures?

Dkb
 
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I have flown a friend's RV-7A with dual mufflers down to zero F and only have to crack the cabin heat. You WILL NOT get cold with this arrangement!
 
dual heat box mounting location

I got a request, so here is where I put my dual heat boxes. They are both stainless. The one in the stock location has the control on the inside and the other one has the control on the engine side.
 
I made a valve that shuts off the air coming into the cab, a three way, that way I can have heat from the left muffler go right into the panel vents. Yup I be spoiled real good with this one. When I turn off the vent heat it actually lets cool air through, not a bunch but nice at 65degrees outside, in the summer I open the valve and let outside air in and of course keep the heat off. In fact if you have a cool morning in the summer time, just open the heat and it still works great with full ouside air coming in.

I went out today and with 10degrees out I had the floor heat on all the way and the vent heat, real nice, could have flown in my tshirt. Oh one more nice thing, I start the engine, I have it plugged in all the time, starts up and already at 70degrees oil heat, almost emediately I have heat coming out the left vent in the panel and I blow it at my glasses, which I keep in the plane, of course there fogged up when I put them on, but a few seconds later there just fine, love that panel heat, oh and forget about the fancy vents, use the vans plastic ones, they leak, so what, there be heat coming out them so who cares.

I put the control valve on the left side about half way up on the firewall, 420hrs and no problems at all, I grab the fresh air from the front inlet left side on the ramp going up to the front cylender and then sent the hose through the underside of the two cylenders.
 
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