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08-12-2014, 08:18 AM
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Join Date: Jun 2005
Location: Georgetown, TX
Posts: 331
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Alternative cabin hot air source...
...I'm not talking about the pilot or passenger
As I was pondering my #4 cylinder temperature/oil cooler temperature/plenum & cowling delta-p, I thought it might be interesting to route the exit air from the oil cooler to the cabin heat valve (instead of from the exhaust shroud).
I'm using a 3" duct to feed the oil cooler currently, and was going to change it to a 2" based on temp & performance data I have.
Has anyone else done this?
B
__________________
Brian Decker
Retired Firmware Guy and Airplane Builder
2020 RV-14 QB -- Under construction - Tailcone & Empennage Complete.
2018 RV-7 QB -- Built, Flying
2007 RV-7 QB -- Built, Drowned, Resurrected and flying
1998 RV-8 QB -- Started, Sold
1986 Mooney 205SE
1980 Mooney 231
Aided and abetted building a number of other RV's.
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08-12-2014, 08:25 AM
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Super Moderator
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Join Date: May 2005
Location: Locust Grove, GA
Posts: 2,627
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Not hot enough
Heat from the oil cooler never seems hot enough to warm the cabin.
Vic
__________________
 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
Kitplanes "Unairworthy" monthly feature
EAA Sport Aviation "Checkpoints" column
EAA Homebuilt Council Chair/member EAA BOD
Author "Pre-Buy Guide for Amateur-Built Aircraft"
www.Baselegaviation.com
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08-12-2014, 09:04 AM
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Join Date: Jun 2006
Location: 8I3
Posts: 3,564
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__________________
Please don't PM me! Email only!
Bob Japundza CFI A&PIA
N9187P PA-24-260B Comanche, flying
N678X F1 Rocket, under const.
N244BJ RV-6 "victim of SNF tornado" 1200+ hrs, rebuilding
N8155F C150 flying
N7925P PA-24-250 Comanche, restoring
Not a thing I own is stock.
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08-12-2014, 09:53 AM
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Join Date: Jan 2005
Location: Round Rock, TX
Posts: 3,778
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Quote:
Originally Posted by rocketbob
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What a great idea!!! 
__________________
Reiley
Retired N622DR - Serial #V7A1467
VAF# 671
Repeat Offender / Race 007
Friend of the RV-1
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08-12-2014, 06:50 PM
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Join Date: Nov 2005
Location: Asheville, NC
Posts: 2,692
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Nice article Bob.
BJ,
We had an unusually cold winter this past year and I was REALLY uncomfortable on two flights. That was with the standard kit setup for RV7A with IO-360-M1B. (There is a new one released this spring by Vetterman. I have the older style)
I added a second muff on Cyl 4, hooked in series with the original muff on Cyl 1 and fed the pair from a manifold on the back of the oil cooler. It did improve the heat but not as much as I expected. Possibly enough that I am done fooling with it. I can't imagine the oil cooler air by itself being nearly warm enough.
__________________
Bill Pendergrass
ME/AE '82
RV-7A: Flying since April 15, 2012. 850 hrs
YIO-360-M1B, mags, CS, GRT EX and WS H1s & A/P, Navworx
Unpainted, polished....kinda'... Eyeballin' vinyl really hard.
Yeah. The boss got a Silhouette Cameo 4 Xmas 2019.
Last edited by rzbill : 08-12-2014 at 07:06 PM.
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08-12-2014, 07:14 PM
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Join Date: Sep 2007
Location: Central IL
Posts: 5,516
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Hmmm. It probably depends on which engine (jets or not) whether there will be enough oil heat in winter. Don't many people completely block off the oil cooler to keep the temperatures up in winter? If so, the colder it gets outside the less heat is available from the oil. 1200-1300F is always available from the exhaust pipes.
Disclosure - I have the AWI exhaust and they have welded studs on on the exhaust pipe under the heat muff. I am counting on them to provide enough heat from one muff down to at least zero F. I also have heated seats.
Maybe AWI would add them to your pipe for a nominal charge. They are resistance welded on with huge threads too.
I suppose if things get worse, I can get heated underwear like Dan H 
__________________
Bill
RV-7
Lord Kelvin:
“I often say that when you can measure what you are speaking about,
and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind.”
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08-23-2014, 02:58 PM
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Join Date: Jun 2012
Location: Erie, CO
Posts: 45
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Cabin heat
I purchased an RV-7A two years ago and read with interest all the folks complaining about not enough heat in the cockpit. I live in the Denver area and take my RV to AZ in the winter to have it with me in my other RV---Winnebago. Last year I flew it down to Coolidge, AZ on Dec. 23rd when Colorado was having some very cold weather. Crossing the Sangre De Cristo mountains and above some show showers, I flew for probably an hour between 16 and 17,500' with an OAT of -35 C. I was very comfortable in just a light jacket. The builder I purchased it from lived in Wisconsin and he has fabricated a plate to place over the opening in the upper rear baffle that goes to the exhaust heat muff, reducing the scat hose opening to only 5/8 ". I suspect that dramatically increases the temperature of the air going to the cabin because of reduced airflow through the heat muff.
Has anyone else done this?
My problem with cockpit temperatures is keeping it cool enough at lower altitudes in the summer, not warm enough in the Winter.
LL
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08-23-2014, 06:22 PM
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Join Date: Feb 2007
Location: Durango, CO
Posts: 126
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I also live in Colorado, so I put some extra effort into the cabin heat. 1. I started off with heated air coming from the bottom of cylinder four (the curved section of the baffle). I welded a 1-1/2" aluminum tube to the curved section and ran a scat tube from there to the heat muff. 2. I changed my cabin side controlled valve to a firewall side controlled, so I could hook a scat tube on the inside of the cabin. 3. I ran a scat tube to the plastic valve and placed it even with the instrument panel, so it can be aimed toward the back cockpit or up at me. 4. I bought two wide mouth baby bottle nipples to cover the fresh air valves to stop unwanted cold air. 5. I sealed the spar braces on the side walls, RV-8A, but think the gear towers on the RV-8 should be looked at also for leaking air.
Even at 20 F or colder I can't hold my hand in front of the valve for more than five seconds. It is that hot and both cockpits are warm. At cruise settings the heat muff can only generate X number of BTUs. The warmer you raise its incoming air the higher the cabin temp will be. Bringing the hot air closer to the crew will also help them feel warmer.
BTW, on my current project I have converted my old cabin side valve to a firewall side by moving the actuator arm to the opposite side of the valve and then riveting a flange, so it goes through the firewall into the cabin. This is easy to do and can save you some money.
On my current project I spent some extra time fitting 1/16" inch rubber sheeting over all the openings (wing attachments, flap rod, rear spar, etc.).
Also, always fly in clothing that you could stay outside overnight comfortably. Hope this helps.
Jim
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08-23-2014, 07:25 PM
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Join Date: Nov 2005
Location: Asheville, NC
Posts: 2,692
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Quote:
Originally Posted by lllewis45
I purchased an RV-7A two years ago and read with interest all the folks complaining about not enough heat in the cockpit. I live in the Denver area and take my RV to AZ in the winter to have it with me in my other RV---Winnebago. Last year I flew it down to Coolidge, AZ on Dec. 23rd when Colorado was having some very cold weather. Crossing the Sangre De Cristo mountains and above some show showers, I flew for probably an hour between 16 and 17,500' with an OAT of -35 C. I was very comfortable in just a light jacket. The builder I purchased it from lived in Wisconsin and he has fabricated a plate to place over the opening in the upper rear baffle that goes to the exhaust heat muff, reducing the scat hose opening to only 5/8 ". I suspect that dramatically increases the temperature of the air going to the cabin because of reduced airflow through the heat muff.
Has anyone else done this?
My problem with cockpit temperatures is keeping it cool enough at lower altitudes in the summer, not warm enough in the Winter.
LL
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LL,
I was very specific about my setup because there are differences in what is available to builders depending on the engine.
So....one important aspect is whether the sump is a vertical intake (carbureted or injected) or horizontal intake (injected only). A second aspect is whether the craft is an A model or not (I see yours is an A). The exhaust designs and available spots for heater muffs are considerably different. It is my understanding that the heater muffs on the carbureted exhausts are much better than the puny unit on the horizontal injected exhaust for A models. Can you specify what is on your purchased craft?
__________________
Bill Pendergrass
ME/AE '82
RV-7A: Flying since April 15, 2012. 850 hrs
YIO-360-M1B, mags, CS, GRT EX and WS H1s & A/P, Navworx
Unpainted, polished....kinda'... Eyeballin' vinyl really hard.
Yeah. The boss got a Silhouette Cameo 4 Xmas 2019.
Last edited by rzbill : 08-23-2014 at 08:11 PM.
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08-24-2014, 08:48 AM
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Join Date: Aug 2014
Location: Canada, well not really at the moment, but where I will build.
Posts: 30
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Quote:
Originally Posted by lllewis45
I purchased an RV-7A two years ago and read with interest all the folks complaining about not enough heat in the cockpit. I live in the Denver area and take my RV to AZ in the winter to have it with me in my other RV---Winnebago. Last year I flew it down to Coolidge, AZ on Dec. 23rd when Colorado was having some very cold weather. Crossing the Sangre De Cristo mountains and above some show showers, I flew for probably an hour between 16 and 17,500' with an OAT of -35 C. I was very comfortable in just a light jacket. The builder I purchased it from lived in Wisconsin and he has fabricated a plate to place over the opening in the upper rear baffle that goes to the exhaust heat muff, reducing the scat hose opening to only 5/8 ". I suspect that dramatically increases the temperature of the air going to the cabin because of reduced airflow through the heat muff.
Has anyone else done this?
My problem with cockpit temperatures is keeping it cool enough at lower altitudes in the summer, not warm enough in the Winter.
LL
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But isn't it important to have a lot of air passing thru the muff heater to avoid overheating and failure? That is why the heater box has 2 positions, one directing the flow into the cabin, the other dumping overboard so you never stop the flow.
I am really interested in the articular about using engine oil for heat, really killing 2 birds with one stone, not only having safe cabin heat but also maintaining a constant oil temp for the engine. Muff heaters and CO have always made me nervous.
Other than possibly an oil line leak spraying hot oil into the cabin, does anyone see a down side to this idea?
Last edited by CDNRV7 : 08-24-2014 at 10:17 AM.
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