From: "Will Chorley" Subject: COZY: Vexed question of Cabin Heat Date: Sat, 29 Aug 1998 17:12:24 -0500 I am struggling, as it would appear many have before me, with the vexed question of how to best provide cabin heat. One thought I had was to use a heat muff (more on this later) and a ducted fan unit from a model aeroplane to move the air up to the front. My son is into model aircraft big time and has all sorts of info on electric ducted fans which move a considerable amount of air. Now about that heat muff! Has anyone got any neat ideas on constructing one for the cabin heat which will take outside air in and heat it to  a reasonable temp. I have the exhaust system from Custom Air parts that has the carb heat muff on the starboard side pipes. The port side pipes are shorter and I'm not sure how to fit a muff on them and get the pipes to and from it. Mine is a 3 place Cozy by the way Thanks to anyone who can help Will Chorley From: cdenk@ix.netcom.com Date: Sat, 29 Aug 1998 20:32:11 -0500 (CDT) Subject: COZY: Cabin Heat THAT WORKS COSY CABIN HEAT: The system I have allows me to fly in short shirt sleeves in Zero F. temperatures. I have the Custom Aero 4 pipe MKIV exhaust systems and a stainless heat muff. Then via 2.5" aeroduct to a combination temperature control/air shutoff valve aft of the firewall, going through the firewall as 2.5" aluminum tubing, then increasing to 3" diameter immediately forward of the firewall, a short piece of 3" aeroduct. The 3" aeroduct has a 3" tubeaxial fan inside it. Then to a 3" inlet, and (2) 2" diameter outlet "Y". Short pieces of 2" aeroduct to 2" aluminum tubing under the armrests both sides. There are short pieces of aeroduct just aft of the front seat back instead of bending the aluminum tubing. There is (2) 1.25" "Y" with flap valve controlled from front seat for rear seat heat. The control is bowden cable with the knob on the front face of the front seat back, behind the front seat peoples outboard elbows. The 2" aluminum tubings has "Y"'s under the control sticks, one branch coming out of the thigh supports for front seat foot heat. The other branch reduces to 1.5" and goes to defrosters in the instrument panel cover. There is a valve flap controllable form just forward of the instrument panel through the leg openings. All aluminum tubing is .049" wall. The fan is a globe motor tubeaxial fan, model #19A820, 3" diameter, 3 1/8" long, 60 CFM at 1.0" water pressure, 12 volt, high temperature grease in bearings. This fan is a high pressure, which is needed to move the air the distance. It weighs 16 oz., and uses 2.75 amps. Contact Globe Motors, 2275 Stanley avenue, Dayton, Ohio 45404, ph: 513-228- 3171. I bought through Hallmark Electronics, offices in many large cities. Price was around $325.00, 6 years ago. I have cabin air exit vents, like reverse gill scoops, at firewall, turtleback is wider than cowling. For the rear headrest, there are (2) 2.5" diameter screened openings. Date: Mon, 31 Aug 1998 08:38:58 -0400 From: "Johnson, Phillip" Subject: RE: COZY: Vexed question of Cabin Heat >Will Chorley writes: Snip> >I am struggling, as it would appear many have before me, with the vexed >question of how to best provide cabin heat. end< > >It would seem that one of the biggest problems with the heating and >ventilation systems in the Cozy/Long is that the heat source is in the back, >and in most cases, the cabin exit vent is also in the back. To ensure that >adequate through flow ventilation is achieved it would seem logical to have >the exit vents at the front. > >Although unproven with flight testing I am installing exits vents below F.S. >0 which will allow the air to flow through the cabin down passed my legs, >keeping my feet warm, then out through these vents. (winters are cold up here >in Canada). These same vents also provide for drains in the fuselage in the >event of water ingress whilst in a parked condition. > ---------------------------------------------------------------------- Phillip Johnson Tel (613) 253 2229 (H) Ottawa, (613) 599 3280 ext. 232 Ontario, Cozy MKIV RG #30 Canada. Subaru EG33 ----------------------------------------------------------------------- > Date: Mon, 31 Aug 1998 08:53:25 -0400 From: Paul Krasa Subject: Re: COZY: Vexed question of Cabin Heat At 17:12 8/29/98 -0500, Will Chorley wrote: >>>> Help! I am struggling, as it would appear many have before me, with the vexed question of how to best provide cabin heat. snip If you have not seen the article in CSA or Kitplanes on cabin heat that recently came out, I would highly recommend getting a hold of it. A new heat system has been developed using a VW Rabbit blower motor and an oil cooler. As soon as I have time, I will perform this mod. Paul Long EZ 214LP From: cdenk@ix.netcom.com Date: Mon, 31 Aug 1998 09:44:25 -0500 (CDT) Subject: COZY: Cabin Heat. The issues with cabin heat are: 1: Heat is tranferred by heating a mass of something, in this case air, and then moving it. So we are talking about a mass (volume at a given temperature/pressure) moving and taking with it the heat. It can be calculated how much heat (BTU/hour) are required, to heat the cabin, assuming inside and outside temperatures. Then knowing the air temperature coming out of the heat muff, a volume (cubic feet per minute) of air flow required is calculated. Then the airway (tubing) area and inside surface roughness can be determined. The original systems have too much friction to allow air to flow fast enough to bring the necessary heat forward. The airway size must be large enough to allow flow rates (feet/minute) to be realistic. If the flow rate is too high, the friction losses are great, and a high pressure blower is required. The idea is to select a airway/blower combination where the airway isn't to great, and the blower is small, lightweight, low power consumption. 2: As my recent message outlined, and without going back to calculations, The airway on BOTH sides the fueslage should be at least 2" diameter smooth inside wall as much a possible. The fan needs to be about 60 CFM at 1"water pressure. For comparison, a 3.6" square muffin (flat computer fan) is only 49 CFM at 0" (ZERO). 3: With reference to the VW fan setup, who has one flying, and what is their experience with flying when ground temperatures are 0 F.? I'm not knocking it but actual conditions are the bottom line. My system has 630 hours on it including 5 Cleveland, Ohio winters. The wife and I frequently fly in the winter, one of our close in trips is to see the ice boats and ice fishing on Western Lake Erie, and we have seen Niagara Falls frozen over. These flights are commonly in our shirtsleeves, taking off our goosedown jackets just be for climbing into the cockpit. 4: I believe bringing hot liquid (engine oil or antifreeze) in the 200 F temperature range into the cockpit area is dangerous. Imagine an oil cooler springing a leak at 10,000 feet, hot oil getting to your feet, It might be the better out would be straight down with the sudden stop. From: cdenk@ix.netcom.com Date: Mon, 31 Aug 1998 09:54:56 -0500 (CDT) Subject: COZY: Cabin Heat In my previous, I forgot to mention: If air is going to enter a closed space, one of 2 things must happen - 1: The air pressure goes up (only slightly in this case), or some air must exit the area. It is necessary to provide a way for the air to exit. Since warm air will rise, the heat must be fed at low points, and exit high. This will prevent stratification (temperature layering). My experience shows that heat must be provided to the front feet area. The feet like to be a little warmer than the rest of the body since circulation and temperature losses of the legs allow you toes to get cold first. We commonly have heat to the feet, and add cool air from the Wemac instrument panel vents. The idea location for the exits is the rear headrest to turtleback forward of the cowling. From: "Nat Puffer" Subject: COZY: cabin heat Date: Mon, 31 Aug 1998 08:41:05 -0500 Cozy builders, In tackling the matter of cabin heat, we considered the first problem was how to collect enough heat from the exhaust pipes. Previous 4-pipe exhaust systems had a heat muff attached to only one pipe. After a brainstorming session with Jack Wilhelmson, we hit on the idea of welding a muff (since changed to clamping it on) on the longest pipe from cylinder #4, and then wrapping a shrould around both #2 and #4. This would then provide twice as much heat as from only one pipe. The next problem was how to get the heat up front. Thinking that I would need a blower, I purchased a number of them. I didn't think an axial blower would put out enough pressure, and the squirrel cage blowers I was able to find were too large to fit forward of the firewall. So I decided to hook it up without a blower. Admittedly we don't fly up north in the winter time, but we do go up to 14,000 where it is pretty cold (below freezing) in the winter in the southern states. We get enough heat forward without a blower so that we cannot fly with heat continuously on. On our prototype, we had cabin exit vents in the back seat, but we don't have any in our plans model. There seems to be enough air leakage to relieve any pressure build up in the cockpit. If you have exit vents, you could actually reduce the pressure inside the cockpit and pull in cold air from outside. We don't have a separate muff for carb heat. We put a tee in the line so we could use the same muff for either carb or cabin heat. We have flapper valves in the carb air box (as shown in the plans) and also one in the cabin heat line. The logic is that carb heat is usually needed (if at all) at idle throttle, before take off, or approach to landing, but hardly ever continuously in cruise, so why have two separate muffs? If you are worried about carbon monoxide, you can buy a carbon monoxide indicator to hang on the instrument panel--we have never experienced any. As far as an oil cooler up front, it adds to the weight you have to lift off the ground, and the more oil lines you have, the greater the chance of leaks, which would sure mess up the cabin and has the potential to fry your engine. We have always believed that the best solution is the simplest one that does the job. It usually results in the lightest and best performing airplane, and the lowest maintenance. Regards, Nat Date: Mon, 31 Aug 1998 11:25:25 -0500 From: Ken Reiter Subject: Re: COZY: cabin heat Hello Guys, I have to second Nat thinking and install. I have a CozyIII and have the setup as per Nat with just two changes: 1.) a cabin exit scoup on the side - to pull area out (read let as MUCH cool air in as possible during the summer in Texas - lost count of the number of days over 100F) anyway the one exit is 1/3 the size of the three inlets combined.) However, with the inlets closed and the cabin heat valve full open (carb heat closed) I was very happy with the amount of air flow from the cabin floor vents at 10,000. 2.) We do have a CO indictor - better safe than ... Keep Building - even in 100F the plane is FUN, Ken Reiter Nat Puffer wrote: > > Cozy builders, > In tackling the matter of cabin heat, we considered the first problem was Date: Mon, 31 Aug 1998 16:13:48 -0400 From: "Johnson, Phillip" Subject: COZY: Cabin Heat Carl Denk Writes: snip> Since warm air will rise, the heat must be fed at low points, and exit high. There seems to be enough air leakage to relieve any pressure build up in the cockpit. If you have exit vents, you could actually reduce the pressure inside the cockpit and pull in cold air from outside. 3: With reference to the VW fan setup, who has one flying, and what is their >experience with flying when ground temperatures are 0 F.? I'm not knocking it >but actual conditions are the bottom line. The answer is: John MacAvoy. See the well-written article in the last Kitplanes (or possibly the one before that). John is based here in the SF Bay Area, but I know he flies back East in cold weather, and on oxygen. He has had plenty of actual experience flying in "real cold". >4: I believe bringing hot liquid (engine oil or antifreeze) in the 200 F >temperature range into the cockpit area is dangerous. Imagine an oil cooler >springing a leak at 10,000 feet, hot oil getting to your feet I agree with you, here. I have a lot of respect for John, (He flew my girlfriend for an air-to-air formation marriage proposal, last October!),but I was planning to open a lively discussion with him, on this very subject. Heat muff air has its hazards, also, in the form of a CO risk. As an A&P, I have found my share of leaks in mufflers with heat muffs, during routine pressure/soap bubble inspections. Nat mentioned that their original heat muff was welded onto the exhaust pipe, but they switched to a clamped-on muff later. I presume this was the reason. IMHO, a good inspection every year should be considered mandatory, as it is with certificated birds. It is really quite easy to do. Just hook up the exaust from your shop vac to the exhaust pipe (make sure both valves are closed, on the cylinder). Duct tape should hold it in place nicely. Squirt a mixture of dish detergent and water all over the pipe or muffler, and watch very carefully for bubbles. It only takes a few minutes, and it could save your life. I also support the CO detecter on the dash. I share your concern for the hot lines in the cockpit. I had thought of using some 1/4 turn ball valves, located right at the engine, and connected such that the simple pull of a cable would valve out the oil cooler, and re-plumb the lines in a "short circuit". It's kind of like the trick we used to do, when a heater hose sprung a leak in the car: cut a short piece and make a little loop from output to input, bypassing the heater core, till you could get home/to a garage and fix it properly. I would personally run aluminum hardline from the firewall forward to near the forward cooler, and keep the flex hoses short. They would be well supported with adel clamps, and protected from vibration-chafing against anything. Aside from the addition of these precautions, I think John's system sounds like a very straightforward solution to the problem. I know that Velocity has used something similar, for years, though I am not familiar with the technical details. I also believe that Nat's per-plans design is very good, and has proved itself on many airplanes. Each solution has trade-offs in weight, safety, complexity, and effectiveness. Properly done, I think I could be happy with either one. It's nice to have choices. --Howard Rogers, 650-926-4052 hrogers@slac.stanford.edu From: cdenk@ix.netcom.com Date: Mon, 31 Aug 1998 19:50:11 -0500 (CDT) Subject: COZY: Cabin heat - comment replys Howard Rogers writes The Cozy heat muff isn't sealed, and the exhaust pipes have slip joints near the flanges, their are kind of loose and do leak slightly, and yes I have a CO detector that is replaced twice a year. The change from welded to clamped heat muff was a result of my observation of long term thermal effects, working with Nat and Custom Aero to improve the situation. I would try to have one valve, and a pressure restriction, possibly a large (relatively) orfice, or lightly loaded spring check valve. One of the real issues is these long lengths of rigid tubing (and for sure I wouldn't use flex) will be cycled through a large temperature range, causing major length changes. If restrained fatigue is likely. There are ways to allow for movement and use rigid tubing. Mechanical engineers designing building steam lines do this regularly. Philip Johnson writes Agree with the comments object is to take advantage of something that is there already. Yes its possible to cause the warm air to flow down, but that takes lots of fan and resulting weight and power consumption. The COSY does not require a huge amount of heat, as a result the airflow in flight isn't that large. I regularly fly in a Mooney M-21J, year around, I can safely say the Cosy is warmer in the cold weather. From: SMilesCozy@aol.com Date: Wed, 2 Sep 1998 20:29:45 EDT Subject: Re: COZY: Cabin Heat In a message dated 98-08-31 10:57:25 EDT, cdenk@ix.netcom.com writes: > Since warm air > will rise, the heat must be fed at low points, and exit high. While this is true in theory, in practice, the air that is already cold at your feet will stay there until it is warmed enough to rise to the exit. On the other hand, if you evacuate the cold air from the bottom, the warm air will "fall" to occupy the space. >From experience in the HVAC field, people with finished basements find they are too cold in the winter no matter how many supply registers they have blowing warm air into the basement. The reason is, all the warm air in the world will stick to the ceiling and go upstairs, never "falling" to the inhabited area. At the same time cold air from upstairs runs down the stairs like a waterfall (very visible with a smoke generator). Since cold air does FALL, unless you remove it, with a "cold air return" within 6" of the floor, it will stay there. Usually the t-stat is upstairs . . . and since warm air rises, your thermostat will be fat, warm, and happy upstairs while your getting uncomfortably cold downstairs. If you run your blower continuously to circulate the air and prevent "stratification," the whole house will remain the same temp, + - a couple of degrees. This same principle applies to cooling the second story in the summer, if the stat is on the first floor, run the blower continuously to evacuate unwanted heat from the ceiling and allow the cooler air to "rise" to replace it. Sorry for the slight detour, maybe it will help someone stay comfortable. To bring it back on topic, FWIW I believe removing the cold air off the floor is equally as important to supplying warm air. I plan to "exhaust" cabin air out the top of the turtle deck, perhaps some of it coming via small ducts (maybe 3/4 X 2) down the sides of the turtledeck, to the rear armrests, and terminating at the bottom by the floor. Of course I'm also considering using rear and front armrests as ducting for additional warm supply air and possibly a defroster. Steve Miles Cozy MkIV 272 Date: Thu, 03 Sep 1998 09:54:56 -0400 From: David Domeier Subject: Re: COZY: cabin heat Nat, If I may add my 2 cents worth to the cabin beat discussion... The Lycoming 0-360 is standard, I believe, in that the oil temp must reach 180-190° F before the poppet valve opens and allows the hot oil to flow to the cooler. I also know from experience, the Cherokee 180 has a cold weather procedure of completely covering the oil cooler with a plate to keep the oil temperature above 180°. So how much warming is one going to get from a nose mounted oil cooler when it is really cold? Not much in my opinion. Also, there will be no warm air after an engine start unless one waits until oil temp opens the poppet valve. It will be some time until the oil pushes its way up to the nose and back. In conclusion, the Velocity system is probably just fine in Florida, but I think exhaust stack generated heat will be more effective when it gets really cold. dd From: cdenk@ix.netcom.com Date: Sat, 5 Sep 1998 08:36:38 -0500 (CDT) Subject: Re: COZY: Cabin Heat On 09/04/98 22:43:21 you wrote: > >In a message dated 9/4/98 8:42:39 AM Central Daylight Time, >cdenk@ix.netcom.com writes: > >> 3 brief comments: Keep it simple, extra weight, keep it down, > >Hi Carl, > >Does this mean the armrests are a good idea in your opinion or not? > > Armrests are a structural member, I was referring to additional ductwork (weight) that doesn't add significantly to the heat/ventilation. And yes my setup is heavier, a calculated additional to make the plane is easily flyable in cold weather. From: SMilesCozy@aol.com Date: Sat, 5 Sep 1998 11:28:09 EDT Subject: Re: COZY: Cabin Heat In a message dated 9/5/98 7:14:24 AM Central Daylight Time, norm.doty@worldnet.att.net writes: > the arm rests are a structural member of the aircraft, thats why they are not > removable, dont omit these Hi Norm, I realize they are structural members and would not consider removing them. What I am considering is using the non-removable structure as ducting, to increase the volume of warm air to the front of the cabin, without adding weight. Since they are a rather large hollow passage running from firewall to instrument panel, sans front seat b-head, all that would be required is a passage through the front seat b-head, of which there are already a few (torque tube, electrical conduit, fuel lines, etc.), perhaps a two inch "lightening hole" (I know, I know, finite element analysis, and change one thing, change many), or maybe just enlarge the passage for the electrical conduit. From: cdenk@ix.netcom.com Date: Sun, 6 Sep 1998 20:37:01 -0500 (CDT) Subject: Re: COZY: Cabin Heat On 09/05/98 11:28:09 you wrote: > >In a message dated 9/5/98 7:14:24 AM Central Daylight Time, >norm.doty@worldnet.att.net writes: > >> the arm rests are a structural member of the aircraft, thats why they are >not >> removable, dont omit these > >Hi Norm, > >I realize they are structural members and would not consider removing them. >What I am considering is using the non-removable structure as ducting, to >increase the volume of warm air to the front of the cabin, without adding >weight. Since they are a rather large hollow passage running from firewall to >instrument panel, sans front seat b-head, all that would be required is a >passage through the front seat b-head, of which there are already a few >(torque tube, electrical conduit, fuel lines, etc.), perhaps a two inch >"lightening hole" (I know, I know, finite element analysis, and change one >thing, change many), or maybe just enlarge the passage for the electrical >conduit. > > On the COSY and the 3 place, the rear armrests start at about the aft top of the front seat back, and go to the rear seat back. The space below the front seat back is open, as far a structure is concerned, a light weight (2 ply BID) guard for linkage, wiring, landing brake linkage, etc. should be installed to protect from luggage. Forget the finite element analysis, the actual loading is very complicated, garbage in garbage out! When you get a large surface area, trying to transfer heat with moving air, the conduction to that large area becomes great (relatively). Instead of finite element analysis, do the calculating on heat loss (whats required to heat) the cabin area, heat transfer of the duct, volume required, etc. My 2" diameter ducts are mostly insulated with fiberax to minimize losses from the duct. Date: Wed, 11 Nov 1998 09:11:32 -0500 From: Bill Theeringer Subject: COZY: Electric heat <> The electric heating system referred to is made by: Composite Aircraft Accessories HOME: 805-964-5454, SHOP: 805-964-5453 E Mail: Composite_Aircraft_Accessories@Compuserve.com PO Box 21645 Santa Barbara, CA 93121 I can send you an e mail version of the info pack if interested. Although delivery times are dismal. Well into next year. BTW, cannot be plumed to any vent. Bill Theeringer N29EZ From: "L. Wayne Hicks" Subject: COZY: RE: [canard-aviators] cabin heat - recirculation Date: Mon, 9 Nov 1998 10:53:27 -0500 -----Original Message----- From: Build2001@aol.com [SMTP:Build2001@aol.com] Sent: Saturday, November 07, 1998 10:43 AM To: canard-aviators@canard.com Subject: [canard-aviators] cabin heat - recirculation [The Canard Aviators's Mailing list] What if air were "recirculated" as in an air conditioning system in cars or homes. The air would naturally be warmer from the start, take less heating and probably require smaller conduit. Ron [L. Wayne Hicks] Someone from the auto industry may want to check on this, but aren't most auto air systems manufactured to recycle some portion of the air to prevent increase of the carbon monoxide? If you do this in the plane, I'd definitely include a CO sensor and an intake/exhaust to immediately draw in fresh air just in case. Wayne Hicks Cozy IV #678 Chapter 8 From: Burton.Donald@orbital.com Date: Wed, 11 Nov 1998 07:44:12 -0500 Subject: Re: COZY: RE: [canard-aviators] cabin heat - recirculation With respect to your first point: 1: Highly unlikely the cabin can be sealed sufficiently to reduce leakage in and/or out. I read an FAA report 2 years ago about a Long EZ who had sealed up his plane for winter and just about killed himself. So it is possible... just not too smart. By the way... there are electric heaters for homebuilts which mounts up by your toes. Some guy on the CA central coast used to advertise in Sport Av. I recall reading somewhere that this was a pretty good system. Comes with everything, blower, and heater elements (like a blow dryer). Could be plumbed to a vent (but some how you had better prevent water from going through it). This would probably be lighter weight and you don't have to run that messy engine oil up to your toes. I think it was only a couple hundred bucks and a day to install. db cdenk@ix.netcom.com on 11/10/98 06:47:15 AM To: hicks@spacetec-inc.com, canard-aviators@canard.com, Cozy_Builders@canard.com cc: (bcc: Donald Burton/ORBVA) Subject: Re: COZY: RE: [canard-aviators] cabin heat - recirculation [The Canard Aviators's Mailing list] Was said 1: Highly unlikely the cabin can be sealed sufficiently to reduce leakage in and/or out. 2: If leakage was ZERO, the within a short period of time the oxygen (required for human life) would get below acceptable standards resulting in hypoxia, one of the side effects is euphoria (don't worry). 3: In the event that harmful gas is introduced into the system, a not good situation will also occur. The gas could be carbon monoxide from the engine or human produced methane. One is odorless, the other has an objectionable odor. 4: Its not that difficult or expensive to make a good heater using the heat muff. \ ->>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>-|- / For details on sponsors of this list, copyrights, and how to remove yourself from this list, please visit: http://www.canard.com/ca-ending.html (c) 1997,1998 Canard Aviators. support@canard.com / -|-<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< \