[skyyking]

Folks, I am in the cold country (WI) and refuse to be uncomfortable in my soon (I hope) completed project. Has anyone out there installed a defroster outlet on the forward glareshield (slider) and has he/she run dual heat muffs to the cabin? I bought the stainless 2" valve which I can "Y" out aft of the firewall. How did you run the lengths of Scat Tubing to keep from toasting your feet and chilling your head?
As always, my sincerest appreciation for your attention.

 

[Greg Arehart]

I put dual heaters in my 9A. One on each exhaust (make sure you get the right heat muff for your exhaust). Each feeds a vent on the same side of the firewall as the exhaust - I eliminated the middle stuff completely. Two vent controls, one for me and one for her. Scat tube for R side comes off the baffles per plans, and I put the second one coming off the baffle on the L side, just in front of the oil cooler (its a tight fit bending the tubing around the cooler and then down to the heater muff - tubing is squashed oval to fit in the space between the engine/oil cooler and cowl). Both heaters are standard Vans muffs with the flap valve on the firewall and positioned about 5 inches up and 5 inches in from the side (make sure to clear all the potential obstacles before cutting these holes!). Works great so far - I can be cooler and the wife can have all the heat she needs on her side.

I did not do anything for defrost, but have read here of folks cutting a few holes in the deck to allow warm air to migrate up from the inlet the heat the canopy in the front.

Cheers,
greg

 

[terrykohler]

Heat Muffs

There's been quite a bit posted on these two subjects in the past. Some builders (myself included) have put muffs on both sides but have run them in series, i.e., feeding into the right muff and routing the exit air into the left muff and from there to the cabin valve. The "preheating" seems to help quite a bit, as I have had no problems in the coldest winters in my bare-metal cockpit.
As to defrosters, the best approach seems to be using computer fans under the glareshield which scavenge the hot air coming from under the IP. You can see a good installation by Roger Bentlage on AFS's site under customer installations. This was done by cutting a round hole in the glareshield, then using black screen and a bezel underneath between the screen and fan:

http://www.advanced-flight-systems.com/Installations/RogerPanel.jpg

I've tried using the glareshield cutouts without the fans. Doesn't work.
Terry, CFI
RV-9A N323TP

 

[andrew phillips]

Last Winter

I don't have defrost. I flew all of last winter in temps that would give your low temps frostbite. If you leave the canopy cracked until just before takeoff the frost is never a problem.

 

[RVRC]

any chance of pics of this Greg?

I put dual heaters in my 9A. One on each exhaust (make sure you get the right heat muff for your exhaust). Each feeds a vent on the same side of the firewall as the exhaust - I eliminated the middle stuff completely. Two vent controls, one for me and one for her. Scat tube for R side comes off the baffles per plans, and I put the second one coming off the baffle on the L side, just in front of the oil cooler (its a tight fit bending the tubing around the cooler and then down to the heater muff - tubing is squashed oval to fit in the space between the engine/oil cooler and cowl). Both heaters are standard Vans muffs with the flap valve on the firewall and positioned about 5 inches up and 5 inches in from the side (make sure to clear all the potential obstacles before cutting these holes!). Works great so far - I can be cooler and the wife can have all the heat she needs on her side.

I did not do anything for defrost, but have read here of folks cutting a few holes in the deck to allow warm air to migrate up from the inlet the heat the canopy in the front.

Cheers,
greg

Greg, if you have photos on both sides of the firewall of this setup, I would love to see them. I, too, am planning a "his and hers" heating as well as heated seats even though I am in the south. My wife wants her sweaters when it gets down to 80^. That and the fact that I plan on flying high whenever possible.

Thanks,

 

[Frank Smidler]

Computer fan defrost

I'm not too far south of you and my set-up worked great during my phase I test fly off last January and February when I flew comfortably in temperatures down to 10 degrees F. I have only one heat muff and no insulation in the cockpit. The real trick is too use only a 1" hole in the rear baffle. If you use a 2" hole to match the scat hose size the heat muff will not be able to heat up the volume of air sufficiently and you will get luke warm air blowing into the cockpit.

I have two computer cooling fans mounted under the glare shield. There is no plumbing to them, they are only pulling warm air from behind the instrument panel. I have only needed them when on the ground taxing, they worked great. In the air I have never needed them.

 

[Noah]

I've always wondered if anybody has done a recirculating heat system in an RV. If you think about it, it is pretty inefficient to heat air up from cold ambient temp to cockpit temperature. Would be nice to have a recirculation option where warm cockpit air is further heated in a muff and sent back to the cockpit. Would not require more than 1 muff, and the size of that muff could be much smaller. Would require two firewall valves, and a recirc fan, but maybe the system weight would be lower? It would certainly be warmer. Concerned about ventilating the cockpit in case of smoke? You would still have fresh air vents for that. Anybody done this?

 

[alcladrv]

The standard single heat muff, 1/2" insulation all around the cabin and firewall, as well as significantly reducing draftiness, kept me warm enough at 7500' last winter when the OAT read minus 10 F. My biggest annoyance was the cold air blowing on the back of my neck from the doghouse on my slider canopy.

As for a defoster, I cut an oblong hole slightly off center to the left side and covered it with a screen. A blower from below would be adequate for defrosting, but I wanted cool air blowing from that area in the summer, too.

I used a Tony Bingelis design that accepts fresh air from a scat tube connected up front on the left inlet ramp. It connects to a 2" T and mixes with warm air from a "Y" off of the heater tube. It clears the windshield on the ground fine. In the air, it's not really necessary.

However, if it's not too cold, I can get enough of a temp rise to melt minor windshield ice.

Insulation accounts for most of the comfort in cold temps. Sealing off drafts from slider canopy rails, cheap plastic air inlets and drafty doghouses, is a close second.

Mike

 

[Greg Arehart]

Robert,

A couple photos attached here. This is the photo of the R side installation and is basically per Vans plans except that the outlet goes into the flapper box on the R side of the firewall. And if I were to do this again, it makes more sense for the waste heat to be vented toward the lower cowl outlet, so I would turn this 90 degrees. Hindsight is 20-20.

Here's an image of the takeoff point for fresh air from the L (pilot) side of the baffling. This was the most reasonable place I could find to put this takeoff. The scat tubing goes from here down to the heat muff and from there into a flap valve similar to the one on the R side (sorry, couldn't find a photo of that). The scat had to be deformed a bit to fit between the cowl and the valve cover without chafing, and I added a bit of red RTV on the scat tubing as well for rubbing protection. Scat is also secured to various places using zip ties and standoffs. I had been worrying about the lifetime of zip ties in the hot engine compartment, but so far (11 months) no issues. Both flap valves are opened from the inside using standard bowden cables that come with Vans heat setup. I just ordered the extra scat, heat muff, flap valve, and bowden cables separately. I threw away (well, kept for other fabrication purposes) the original center baffling stuff. And I obviously did not cut the center vent hole. Don't have a photo of the interior setup, sorry on that account.

Hope this helps. Feel free to email or continue the conversation if needed.

greg