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Cold air from heat vent!!!

Majorpayne317641

Majorpayne317641

Well Known Member
It was a whopping 1 degrees F flying today at 8k ft, this southern RV-8 didn’t seem to like that as it rewarded me with cold air blowing from the heat vent.

I only have one heat muff on a vetterman pipe from the #1 cylinder. The engine simply was not making enough heat. What do all the northern planes do? Should I try steel wool? Two heat muffs for winter ops?
 
At 8k, even at WOT you can probably lean to peak while staying out of the red fin on the cylinder pressure chart - that will help with available heat exchange if you're not already there. Other than that and sealing drafts, you probably need more muffs and some stuffing inside of them - not sure this nut has ever been cracked any other way.

Blankets, at least for the pax, can help, as can heated seats. Both might be easier to implement than adding heat muffs and SCAT. I put only one muff in the -10 and sometimes the rear seat pax appreciate the blanket; I've never needed more BTU's except the time when the flapper was disconnected from the Bowden cable and I didn't realize it in flight.
 
Some things to try:
- Adding Stainless Steel scrub pads to the inside of the heat muff. Do not use Steel Wool. Thsee will provide more heat transfer from the exhaust pipe as well as slow down the air. While you get less total air flow, the air you get is hotter.
- At altitude run the engine at Peak or just LOP. The fuel economy will be about he same and your exhaust pipes will be warmer.
- Make sure your cabin heat box goes all the way when shifting from no heat to heat. If just a little open to the bottom cowl area you will get only slightly warm air.
- After the GIB complained about a recent high, cold cross country I added another layer of Velco (the fuzzy side only) to the rear canopy skirt. This was a huge improvement.
- Now that the canopy air leak is tamed, I notice the air coming in via the aileron push tube holes in the sides of the fuslege. This is the next thing to fix.
- You can add a second heatmuff. Put the heat muffs in series, not parallel. If I lived further north I might do that.

My last trip at 11K’ and OAT down to 17 degrees was comforable with just a sweater. I note however that I travel high (gain in fuel economy range and as mitigation against icing). Above the mess the sun does a great job keeping the cabin warm through the canopy.

Carl
 
At 17 degrees F the heater works ok. Yes I run at peak/LOP at cruise. I have the canopy sealed very well with an AC style 1in x 1in open cell foam that fills voids pretty well. I had to replace it after 2 years because I noticed it wouldn’t fill gaps as well when it got cold this season. The only draft left is coming out of the rear stick area which is most likely the aileron tubes. Yes I agree the sun works well. This is why I shut the heater door because the sun was giving more heat than the heat muff could at 1 degree F. At night this would obviously be worse.

Does anyone have any example pictures of dual heater muffs in series on an RV-8A?
 
Electric seat heaters are amazing. And then do something about the floor so your feet aren't in direct contact with cold aluminum. Even 3/32" plywood is going to be better.
 
Majorpayne317641 said:
At 17 degrees F the heater works ok. Yes I run at peak/LOP at cruise. I have the canopy sealed very well with an AC style 1in x 1in open cell foam that fills voids pretty well. I had to replace it after 2 years because I noticed it wouldn’t fill gaps as well when it got cold this season. The only draft left is coming out of the rear stick area which is most likely the aileron tubes. Yes I agree the sun works well. This is why I shut the heater door because the sun was giving more heat than the heat muff could at 1 degree F. At night this would obviously be worse.

Does anyone have any example pictures of dual heater muffs in series on an RV-8A?
Click to expand...
Highly likely that's where your cold air is coming from so you might try some pushrod boots like this:

Final-208.JPG

I got these from FlightLine Interiors when I got the seats done. Like others have mentioned, bottom and back seat heaters work great and running LOP to heat things up. I also added a "defrost" fan under the glareshield that brings the air up from that floor vent and blows it to the windscreen. Works good for defrosting and it also distributes the air to the rear seat. It also depends on what kind of fresh air vents you've got. If it's the cheap plastic ones that you get with the kit they will not seal very well when closed.
I've got a single heat muff on my exhaust and have flown to Minnesota in the winter wearing nothing but short shirt sleeves. Those are some large openings where the pushrods come through. I'd start with that or your fresh air vents. Hopefully you screwed the floor down so you don't have to drill out rivets for access.
 
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