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Oil Heat for the Cockpit?

fly3g

Active Member
Has anyone tried (Lycoming) to run a parallel circuit to the oil cooler through a second oil cooler in the cockpit to provide cabin heat? My Rotax ride uses a parallel coolant loop through a heater core with a fan in the cockpit which does a super job in the winter (like a car). Just thinking some :

Pros ? smaller firewall penetrations, no exhaust fumes sneaking up on you and a fairly consistent heat source point. Not as much cold air circulating into the cabin to heat up. Could possibly also use it as an extra heat dump on a prolonged climb in a pinch.

Cons ? if it springs a leak would have hot oil dripping,spraying on you, not as hot a heat source as the exhaust pipes so maybe less efficient system, takes longer to heat to an operating temperature. Installation may be heavier than traditional exhaust heat ducting.

Just curious if anyone has tried this prior to taking any action on it myself.

Thanks, Gregg
 
There have been a few Rutan canard variants done this way with reported good results. It all depends how cold of temps you want to fly in. If you fly at -20C the oil will barely make min operating temps even with the cooler blocked completely off, and adding a cockpit radiator won't help.

Down to about -5 C to -10C OAT it should work so long as you can keep the engine oil at 180 F
 
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Down to about -5 C to -10C OAT it should work so long as you can keep the engine oil at 180 F

This is why it doesn't work. In the temps you need the most heater performance. Most people are blocking off their oil coolers to try and get the oil temp up to somewhere near normal.
 
The Prescott Pusher was designed and built with 2 oil coolers in the front of the aircraft to be used for cabin heat. As cabin heaters, they were worthless when you wanted heat.

Vic
 
Oil cooler heat

So, I've taken a slightly different path with my cabin heat. Granted I fly in the Pacific NW so it doesn't get much below 0 when I fly in the winter at altitude but this setup has been fine for me. I take the exit air from my oil cooler, duct it down with a flapper valve on the outlet (that I've never had to use). On that exit duct I have a 2" flange that I use to pull cabin heat hot air. You can see from the picture below that I have my oil cooler mounted on my firewall and it is supplied by a 4" inlet duct. One more caveat, I have piston oil squirters, cold air induction, and electronic ignition so my oil gets the heat in my engine, not the cylinder heads. I've never had to block cooling air to my oil cooler to get my temps up to 180. It takes some aggressive climbs during the coldest days but I can always get my oil temp to 180.

In this picture you are looking aft at the mid/lower right side of the firewall. The oil cooler is on the top of the picture and is fed with cool air from the inlet plenum. The air flows down through the oil cooler into this duct. The duct is a 3D printed proof of concept that I flew with a few times to make sure the dimensions were correct and that the airflow was adequate. What you can't see very well is the outlet which is facing down at about 7 o'clock. There are holes in each end for me to put my flapper valve in if I ever need to control oil temperature. The flapper valve restricts flow after the cabin heat air outlet so I always have hot air.

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At least in the RV-10, the stock heatmuff system works very well, almost too well. I see zero benefit from trying to reinvent the wheel on this.
 
My hangar-mate has a 200hp IO-360 in his RV8A. Its cabin heat system either lets air free-flow through the oil cooler, or diverts that airflow to the cabin. Net effect as a cabin heater is NIL. His next mod is to install exhaust heat muffs.
 
I did something similar to Zuldarin, only not so fancy. I just Ty-Rapped a 1-1/2" SCAT duct under the oil cooler air outlet and fed it through a butterfly valve into the cockpit. The coldest I've flown in is -10C, but it worked well at that temp.
 
Yes, I duct my oil cooler outlet to a mix valve on the firewall. It either goes down through a duct to the bottom of the firewall or pull a cable and it then goes into the cabin. Very simple, gets plenty hot, no CO concerns. I live in South Texas though. I have individual plenums on each Bank of cylinders, oil squirters, angle valve, so my engine puts a lot of heat in the oil.
 
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i had my oil cooler line fail while flying my RV-4, hot oil onto my foot through the heater valve which was right below the oil cooler on the firewall side

i can tell you with enthusiasm, keep the oil out of the cockpit
 
It seems that a heat muff with stainless steel wool or welded on studs works so well that I can't see the point of doing something this complex. I don't mean to sound negative but you can get tons of heat by just getting the surface area up and slowing down the air flow to give it more time to heat up.
 
It seems that a heat muff with stainless steel wool or welded on studs works so well that I can't see the point of doing something this complex. I don't mean to sound negative but you can get tons of heat by just getting the surface area up and slowing down the air flow to give it more time to heat up.

There are a couple of reasons for doing this but the main reason was that I eliminated a 2" hole in my baffles by using the air already destined for the oil cooler. More airflow through the cylinder fins. :)
 
Get some exhaust wrap and just wrap the heater muff, not the exhaust pipe(s). That will make a big difference in the heat output without having to resort to steel wool or other tricks.
 
Oil cooler heat

Looks like the wheel is being invented here again. The year was 1985 and I was stationed in West Texas. I fabricated an oil cooler heater in my -4. Worked fairly good in temps down to @ 40. So I loaded up my new wife and headed up to South Dakota. When we left there to go back to Texas, the temperature was a balmy +5 F. We both froze our as**s off and I lost feeling in my feet. I was concerned about landing with numb feet, but no problem. First fuel stop Garden City Ks, new wife tried to find other means of getting home. She didn't want to get back in what she called "the meat locker". I finally convinced her that it would get warmer the farther south we went. Not so, it was cold the whole way. Ya, we were like ice cycles again. At that point she was speechless-for about 3-4 days. My next project was to do away with that system and install heat muffs. It took some convincing to get her back in the -4 again. Later on I stopped in Garden City and the young lady behind the counter said, "I remember you, can I ask you a question? Sure, no problem. She wanted to know if I was still married!! Remembering the conversation the last time there. Ah yes memories of the -4 days. So go ahead guys. Fabricate your oil cooler heaters and have fun. I hope your more successful at it than I was. Larry v.
 
Thanks, great info

I appreciate all the comments and personal experiences. Kind of confirmed what I was thinking in that the heat source isn't as efficient in transferring heat into the air (smaller delta T) if the airflow is controlled. Thanks will probably rig traditionally.
 
I asked the same question a couple of years ago, as I was interested in getting some heat to the back seat. Bottom line is when you need the heat, the oil really isn't hot enough, and secondly, most concluded that they didn't want oil lines running in the cabin. I tend to agree. I believer that Velocities may do this, though. Mike Stewart and a few others have cut a hole in the web spar and run a duct to the back seat area with good success. You can see his solution on his website. Of course, you are off off Van's plans at this point, so do so at your own risk. I do have the details from Bill Palmer along with photos. If you are interested, send me a PM and I can forward them to you.
 
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