Heat exchanger muff project
Posted: Sat Oct 30, 2021 9:20 am
by Wood
Good morning everyone! Hope your all doing well.
I’m thinking of building a heat exchanger muff over the winter and was wondering if anyone knows of any drawings out there that I could follow. I’ve been looking at this one https://www.aircraftspruce.ca/catalog/eppages/turboheat05-15249.php from aircraft spruce but thinking it would be a fun project over the winter. Im not sure if 8 inches would be a little to long and would need to shorten it a bit. Any suggestions would be very much appreciated.
Cheers
Mark
Re: Heat exchanger muff project
Posted: Sat Oct 30, 2021 10:35 am
by Bryan Cotton
Be sure to read this:
viewtopic.php?f=7&t=4730
And this:
viewtopic.php?f=7&t=5366&p=40644
Re: Heat exchanger muff project
Posted: Sat Oct 30, 2021 11:07 am
by XenosN42
Wood wrote:Good morning everyone! Hope you’re all doing well.
I’m thinking of building a heat exchanger muff over the winter and was wondering if anyone knows of any drawings out there that I could follow. I’ve been looking at this one https://www.aircraftspruce.ca/catalog/eppages/turboheat05-15249.php from aircraft spruce, but thinking it would be a fun project over the winter. I’m not sure if 8 inches would be a little too long and would need to shorten it a bit. Any suggestions would be very much appreciated.Cheers
Mark
I have used the heat exchanger in the link and it’s great. I’d recommend it unless your need to build your own is greater than your need for cabin heat.
Re: Heat exchanger muff project
Posted: Sat Oct 30, 2021 10:21 pm
by mike.smith
I’ve tried on several occasions to make my own heat muffs, with not a lot of success. I ended up using TWO of the AC Spruce ones. Each is on a different exhaust pipe, and both feed into a single scatt tube to feed the cockpit.
Not sure about a Jab 2200, but with a VW even 2 muffs only puts out minimal heat. So it works OK for outside air temps in the 50s (Fahrenheit), but anything lower and its just blowing cold air into the cockpit. I played with various restrictors and lots of other variables for 4 years. You name it, I’ve tried it. Too much air flow and all you get is cold air. Too little air and there is little heat that gets to the cockpit.
If you have more luck with a Jab 2200 I’m sure we’d like to hear about it, but on a VW there just isn’t enough heat being produced from the engine. Think about it… how well did a VW bug do with heat in the winter!?
Re: Heat exchanger muff project
Posted: Sun Oct 31, 2021 8:48 am
by GraemeSmith
Straight and level - shoes off - socks on firewall. Toes stay warm.
I did look at these this year:
https://www.homedepot.com/p/Milwaukee-M … /313562987
Re: Heat exchanger muff project
Posted: Sun Oct 31, 2021 9:06 am
by Wood
Bryan Cotton wrote:Be sure to read this:
viewtopic.php?f=7&t=4730And this:
viewtopic.php?f=7&t=5366&p=40644
Hi Bryan. Thanks for this. Great info.
Mark
Re: Heat exchanger muff project
Posted: Sun Oct 31, 2021 9:10 am
by Wood
XenosN42 wrote:
I have used the heat exchanger in the link and it’s great. I’d recommend it unless your need to build your own is greater than your need for cabin heat.
Hi Michael
Thanks for this. I was looking at this one for sure but thought it would be fun to fabricate one over the winter. It looks like I’ll just bet this one.
Mark
Re: Heat exchanger muff project
Posted: Sun Oct 31, 2021 9:22 am
by Wood
mike.smith wrote:I’ve tried on several occasions to make my own heat muffs, with not a lot of success. I ended up using TWO of the AC Spruce ones. Each is on a different exhaust pipe, and both feed into a single scatt tube to feed the cockpit.
Not sure about a Jab 2200, but with a VW even 2 muffs only puts out minimal heat. So it works OK for outside air temps in the 50s (Fahrenheit), but anything lower and its just blowing cold air into the cockpit. I played with various restrictors and lots of other variables for 4 years. You name it, I’ve tried it. Too much air flow and all you get is cold air. Too little air and there is little heat that gets to the cockpit.
If you have more luck with a Jab 2200 I’m sure we’d like to hear about it, but on a VW there just isn’t enough heat being produced from the engine. Think about it… how well did a VW bug do with heat in the winter!?
Hi Mike. Appreciate your advice. Just to test and see if it would work i did connect a scary hose into the cabin box up to the muffler muff just to see if it would pick up a enough heat to make it worth while. What I found was a significant change in the cabin. However, because the end of the scary hose was open and close to the muffler muff I found great heat at slower speeds as and as speed increased heat decreased as the airflow washed it out. So I’m thinking if it was definitely connected to the muff or the a heat exchanger then it would work perfectly. I would be flying in temps below -10 decrees C but it will be something.
Thanks a lot
Mark
Re: Heat exchanger muff project
Posted: Thu Nov 04, 2021 7:38 pm
by mike.smith
Wood wrote:
Bryan Cotton wrote:Be sure to read this:
viewtopic.php?f=7&t=4730And this:
viewtopic.php?f=7&t=5366&p=40644Hi Bryan. Thanks for this. Great info.
Mark
Those posts are regarding a turbo AeroVee. I’m guessing there is a lot more heat to be had. I still have not seen proof of any successful heating solution off of a standard VW engine. I’m hoping someone someday will have empirical evidence and photos. Maybe if I remember I’ll make a video of my installation and post it on YouTube.
Re: Heat exchanger muff project
Posted: Fri Nov 05, 2021 11:23 am
by WesRagle
Hi Guys,
mike.smith wrote:I still have not seen proof of any successful heating solution off of a standard VW engine. I’m hoping someone someday will have empirical evidence and photos. Maybe if I remember I’ll make a video of my installation and post it on YouTube.
I love to fly on crisp wind free mornings. This morning was just such a morning.
Forecast from yesterday evening:
I read Mike’s post last evening and decided to take my little digital thermometer and a camera with me to the airport for my morning flight. The thermometer has been checked with the standard ice bath/boiling water test and is accurate.
Ignore the reading on this pic. The thermometer had just been pulled out of the warm truck and stuck to the panel. I had handled the probe and there was no airflow in the cockpit. The pic shows the thermometer stuck to the panel with probe dangling just below the panel.
I took off right at morning civil twilight, so no solar heat in the cockpit. The KMWL WX ASOS was reporting 3 Deg. C. The field elevation is ~1000 ft. I took off and climbed to 3500 ft. and then started fumbling for the camera.
Hard to see in this pic but the oil temperature was up to 185 Deg. F. I had climbed close to 3000 ft. If you assume the standard temperature laps rate, OAT when the pics were snapped would have been about 26 Deg. F.
The temperature of the air coming into the cockpit as measured just below the instrument panel was approximately 84 Deg F.
It was quite comfy in the cockpit. After 15 minutes of getting me back up to temp from a cold pre-flight I actually had to turn the heat down some.
Wes
Re: Heat exchanger muff project
Posted: Fri Nov 05, 2021 5:04 pm
by mike.smith
Wes,
If you seem to have the magic bullet I’d love to see pictures of your setup! You’re the only person I’ve seen success from, with empirical data to back it up.
Re: Heat exchanger muff project
Posted: Fri Nov 05, 2021 9:05 pm
by WesRagle
Hi Mike,
mike.smith wrote:Wes,
If you seem to have the magic bullet I’d love to see pictures of your setup! You’re the only person I’ve seen success from, with empirical data to back it up.
When you think of the heater core in your car, what do you think of? Maybe a nice heat exchanger with 160 to 230 Deg. F. liquid flowing through it? Sounds a lot like the Oil Cooler most of us carry around on our airplanes all the time.
Here is how I did it.
I bought what I consider to be a quality oil cooler. They aren’t that expensive. If you consider the cost of a standard VW oil cooler and add the price of one of those god awful expensive heat muffs it’s probably a wash.
I built a plenum on each side of the oil cooler and mounted it to the firewall. Here is a pic of the assembly while I was trying to lay out my firewall.
As shown, the output is routed to one of the simple cabin heat flappers (via a 2.5" to 2" silicon reducing elbow).
The input to the oil cooler is via a 2.5" NACA vent. I don’t like having to drop hoses when I remove the cowl so I hinged the the NACA vent to the firewall and pulled it to the cowl side with four quarter turn fasteners.
That’s really all there is to getting good cabin heat. It’s simple and neat without SCAT running all over the place.
Problems I had …
I didn’t lay things out as well as I could have and the path from the NACA to the cooler inlet is a little convoluted. So, I had to add a little scoop to augment the airflow through the cooler.
I couldn’t find a rigid 2.5" NACA so I had to buy some appropriate aluminum tubing and rivet it to the NACA outlet so I would have something solid to clamp to.
Tongue in Cheek → I’ll never understand why folks keep trying to heat their airplane by sticking a tin can on the tailpipe when they have a perfectly good heater core just begging to be used.
Wes
Re: Heat exchanger muff project
Posted: Fri Nov 05, 2021 10:51 pm
by Mike53
Brilliant!!!
Re: Heat exchanger muff project
Posted: Sat Nov 06, 2021 12:43 am
by BRS
Wes,
Thanks for posting that wonderful solution. What caught my attention was that I have two heater cores on my bench which I took photos of yesterday so I could sell them. Seems I’ll have to hold onto one of them. I don’t yet have any heat.
Q: Did you just plumb the “heater core” in series with an unmodified oil cooler?
Q: When you don’t want heat does the valve just block the air to the cabin or does it dump it overboard like many purchased heat valves?
Q: Did you use a 7 layer core as in your link?
?: This could possibly be used during the summer to augment your oil cooler on a hot day’s climb?
Re: Heat exchanger muff project
Posted: Sat Nov 06, 2021 6:12 am
by kmacht
Wes,
What temperatures do you typically fly in with the heater and what temperature air do you get coming out the vent. When Mike says he hasn’t been able to get a heat muff to work it’s likely because he lives in the northeast where daytime highs are below the freezing mark during the winter. Your solution seems pretty elegant but I wonder how well it still warms things up when the outside air temp drops into the 20s as typical when flying up north.
Keith
#554
Re: Heat exchanger muff project
Posted: Sat Nov 06, 2021 9:44 am
by WesRagle
HI Brock,
Q: Did you just plumb the “heater core” in series with an unmodified oil cooler?
A: No, I only have one heat exchanger. I referred to the oil cooler as a heater core trying to make the point that it could be used for both.
Q: When you don’t want heat does the valve just block the air to the cabin or does it dump it overboard like many purchased heat valves?
A: The “heat valve” is a purchased parts that dumps the output overboard if not needed.
Q: Did you use a 7 layer core as in your link?
A: I think so. It’s been a while. The oil cooler is made by AAVID NIAGARA out of Niagara Falls , NY. Part number 20002A. When I purchased it I was just looking for the smallest “real” oil cooler I could find.
Hi Keith,
Q: What temperatures do you typically fly in with the heater and what temperature air do you get coming out the vent.
A: Ref. https://sonexbuilders.net/viewtopic.php?f=8&t=6505#p49358
Wes
Re: Heat exchanger muff project
Posted: Sat Nov 06, 2021 11:42 am
by BRS
Wow, Wes,
If I had seen your pictures on this 3 months ago it would have made a big difference in how I modified the cowl when installing the RevMaster. Had to bump the cowl for their oil cooler. Ha, I should have just removed the cooler.
I can see though that I might do that anyway, in the future, just that I’ll have some needless cowl warts.
It’s stuff like this that make these ‘type’ forums so valuable.
Re: Heat exchanger muff project
Posted: Sat Nov 06, 2021 3:38 pm
by WesRagle
HI Guys,
Mike53 wrote:Brilliant!!!
BRS wrote:
It’s stuff like this that make these ‘type’ forums so valuable.
Thanks for the kind words.
Getting enough cabin heat from a VW has been a long standing problem. Back when I built #664 I was determined that I would have enough cabin heat. So, I came up with using the oil cooler for cabin heat. I planed on adding a heat muff in series with the oil cooler if the oil cooler alone wasn’t enough.
It turned out that the using the oil cooler alone was enough. So, the 15 year old heat muff got repurposed to provide carb heat for the Zenith on my Onex.
Wes
Re: Heat exchanger muff project
Posted: Sat Nov 06, 2021 9:17 pm
by Scott Todd
I have the top mount oil cooler on my Onex and I keep thinking about making a simple diverter box to direct it to a piece of scat tubing to the lower the cabin. There is plenty of room there and I thought I could make it easily removable for maintenance or summer flying. Hmmm…
Re: Heat exchanger muff project
Posted: Wed Nov 10, 2021 12:05 am
by mike.smith
WesRagle wrote:Hi Mike,
When you think of the heater core in your car, what do you think of? Maybe a nice heat exchanger with 160 to 230 Deg. F. liquid flowing through it? Sounds a lot like the Oil Cooler most of us carry around on our airplanes all the time.
Here is how I did it.
That’s cheating! Just kidding… Obviously this isn’t a “heat muff” solution, but it’s obviously a viable solution. Might be less practical to retrofit into a completed engine compartment, but certainly a possibility for those who haven’t done their firewall forward, yet.
For anyone who has been trying to get a heat muff to work, I did a video walk-through of my setup, which only works marginally well.
https://www.youtube.com/watch?v=I29LCu-c_Bc
Re: Heat exchanger muff project
Posted: Wed Nov 10, 2021 12:35 pm
by WesRagle
HI Guys,
mike.smith wrote:That’s cheating!
I would sometimes eat lunch with an avid drag racer I used to work with. From him I learned the guiding principle that all drag racers live by. I think it applies here.
“If you ain’t cheat’in, you ain’t try’in”.
Some observations.
Assuming you don’t blast the sump, and ignoring the fact that my valve covers are hanging out in the wind, with the oil cooler cabin heat solution 100% of the thermal energy being extracted from the oil passes through the cockpit. Now, just like with the heat muff solution, it’s a matter of balancing air flow with air temperature. But, you really don’t have a choice with air flow. Since the primary function of the cooler is to cool the oil you have to accept whatever airflow is required to do that. The only way to change the airflow/air temperature equation is the change to a more/less efficient oil cooler.
Also, unlike the heat muff solution, there is a limited amount of heat available. It just happens to work out that the heat available is just enough.
So, it’s just a matter of dumb luck that the oil cooler I chose and the amount of thermal energy available in the oil worked out to a satisfactory solution.
Concerning the heat muff solution, the problem faced is how to extract the heat from a near unlimited supply. Various techniques have been tried to increase the efficiency of heat muffs. The one that makes the most sense to me is modifying the muff by using a stretched out spring coiled around the exhaust pipe. You might pick up a little heat transfer from the spring but I believe the primary benefit would come from adding turbulence to the air flow. I don’t know, I’ve never tested it.
One thing for sure, the pipes are hot. If you could keep the air in the muff longer (while maintaining a suitable flow rate) more heat would be transferred. The only way I see to do that is increase the diameter/volume of the muff. Since the typical muff designs aren’t very “fat”, and since a lot of the internal volume is taken up by the pipe itself, a small increase in diameter would double the volume of the muff thus keeping the air in the muff on average twice as long.
So, that’s what I would try. Add some turbulence to the airflow through a muff of increased diameter.
Wes
Re: Heat exchanger muff project
Posted: Wed Nov 10, 2021 5:55 pm
by mike.smith
WesRagle wrote:HI Guys,
Assuming you don’t blast the sump, and ignoring the fact that my valve covers are hanging out in the wind, with the oil cooler cabin heat solution 100% of the thermal energy being extracted from the oil passes through the cockpit. Now, just like with the heat muff solution, it’s a matter of balancing air flow with air temperature. But, you really don’t have a choice with air flow. Since the primary function of the cooler is to cool the oil you have to accept whatever airflow is required to do that. The only way to change the airflow/air temperature equation is the change to a more/less efficient oil cooler.
Also, unlike the heat muff solution, there is a limited amount of heat available. It just happens to work out that the heat available is just enough.
So, it’s just a matter of dumb luck that the oil cooler I chose and the amount of thermal energy available in the oil worked out to a satisfactory solution.
Concerning the heat muff solution, the problem faced is how to extract the heat from a near unlimited supply. Various techniques have been tried to increase the efficiency of heat muffs. The one that makes the most sense to me is modifying the muff by using a stretched out spring coiled around the exhaust pipe. You might pick up a little heat transfer from the spring but I believe the primary benefit would come from adding turbulence to the air flow. I don’t know, I’ve never tested it.
One thing for sure, the pipes are hot. If you could keep the air in the muff longer (while maintaining a suitable flow rate) more heat would be transferred. The only way I see to do that is increase the diameter/volume of the muff. Since the typical muff designs aren’t very “fat”, and since a lot of the internal volume is taken up by the pipe itself, a small increase in diameter would double the volume of the muff thus keeping the air in the muff on average twice as long.
So, that’s what I would try. Add some turbulence to the airflow through a muff of increased diameter.
Wes
Hi,
The valve covers aren’t hanging in the wind; they are under the baffle material and have no air flow over them. So they stay pretty toasty.
I tried the springs inside and that didn’t make a difference. As I noted in the video I have tried many iterations on changing the area of the inlet and the outlet, and what I have now produces the best, though not satisfying, results.
The muffs that I have are the ones custom made by a guy for AC Spruce, and they have lots of metal “spikes” inside to capture heat, rather than using springs. The muffs are about as wide as they can get without beginning to impinge on things in the engine compartment, especially the pushrod tubes. I think the “muff” solution for a VW is just never going to prove to be effective. I would love for someone to prove otherwise, so anyone who wants to experiment should use what I’ve learned and let us know if you get any useful improvements in the system.
Re: Heat exchanger muff project (RevMaster thoughts)
Posted: Wed Nov 10, 2021 9:07 pm
by BRS
I asked Joe at RevMaster about moving the oil cooler (so as to use it for heat) and if the air going over the oil pan fins was important. His answer was interesting and informative (ie. Didn’t realize my case is magnesium). Here is what he had to say…
The linear expiation coefficient of your magnesium engine case
is a issue. Iron is 10 aluminum is 21-24 mag is 25-26.5
The hotter the case temp the larger the main bearing bores become
and the strength of the case depreciates.The oil temp represents the temprature of the case. We try to keep the
oil temp around 180 F or lower. Hot day climb outs included. The engine
is oil cooled as well as air cooled. Over the years our competitors have
run oil temps as high as 240F resulting in many negative issues including
damaged engine cases.
Re: Heat exchanger muff project
Posted: Wed Nov 10, 2021 9:20 pm
by GordonTurner
Wes.
How is the oil cooling in the summer. Is the airflow through the cooler when the firewall valve is in “bypass” approximately the same as the normal oil cooler installation would experience? I am impressed by your setup for the heating in the winter end of the operation, but have you used it during the cooling in the summer end? Very nice fabrication.
Gordon
Re: Heat exchanger muff project
Posted: Thu Nov 11, 2021 11:43 am
by WesRagle
HI Guys,
Mark: Sorry that your thread got hijacked. It wasn’t my intent.
GordonTurner wrote:How is the oil cooling in the summer. Is the airflow through the cooler when the firewall valve is in “bypass” approximately the same as the normal oil cooler installation would experience? I am impressed by your setup for the heating in the winter end of the operation, but have you used it during the cooling in the summer end? Very nice fabrication.
Right now the summer performance is just OK. It’s pretty much balanced with CHTs. As long as CHTs aren’t approaching 400 Oil temp will be fine. Last summer I don’t recall seeing Oil Temp above 210.
Just looking at the setup you might expect the limiting factor to be the the small outlet at the flapper valve. That’s not the case. It’s all about the oil cooler input. I’ve learned that twice now, once on #664 and again on the Onex. Here is a link to a post I made while trying to get my Oil Temps under control.
https://sonexbuilders.net/viewtopic.php?f=5&t=5226&start=150#p43598.
If the little scoop would not have worked I would’ve had to flip/swap things around and figured out how to go with pure ram air, maybe off the rear baffle.
BRS wrote:
The oil temp represents the temprature of the case. We try to keep the
oil temp around 180 F or lower. Hot day climb outs included. The engine
is oil cooled as well as air cooled. Over the years our competitors have
run oil temps as high as 240F resulting in many negative issues including
damaged engine cases.
That’s interesting. I doubt many VW guys keep their oil that cool on climb out. I’m curious where oil temperature is measured on the RevMaster. There can be a lot of variation depending on where it’s measured and the airflow around the sensor and surrounding case. Here is a link to a discussion of oil temps showing how sensor readings can be influenced by air flow around the sensor.
https://sonexbuilders.net/viewtopic.php?f=21&t=5124&hilit=thermal+sensors&start=10#p38921
Worst case, https://shop.vansaircraft.com/cgi-bin/shop.cgi?ident=1636601427-228-249&browse=engines&product=oil_shutter
Wes
Re: Heat exchanger muff project
Posted: Thu Nov 11, 2021 1:35 pm
by BRS
WesRagle wrote:HI Guys,… I’m curious where oil temperature is measured on the RevMaster. …Wes
R2300 Oil Sensor is mounted on the back right side (passenger) of the oil sump. Thus the sensor is in the oil of the sump.
Re: Heat exchanger muff project
Posted: Thu Nov 11, 2021 2:15 pm
by Wood
WesRagle wrote:HI Guys,
Mark: Sorry that your thread got hijacked. It wasn’t my intent.
Wes
Hi Wes
No apologies needed. It’s all good, we’re all here for one reason. Thank you for the info on this and if I may say. Fabulous idea. I’ll come back to this when I get my other issue figured out.
Mark.