Heater Valves and Effective Cockpit Heating

Noah · #1 02-11-2008, 11:17 AM

A good topic for the middle of winter... EMP AV offers several models of stainless firewall mounted heater boxes:
http://www.epm-avcorp.com/ssdiv.html
and Avery sells them too:
https://www.averytools.com/showcateg...setfilter=true

One model allows a scat tubing to be connected aft of the firewall, but requires a separate firewall penetration for the control cable.

The other model does not allow for any kind of scat tubing connection aft of the firewall, but does not require a second penetration for the control cable (the actuating lever is in the middle of the port). The vans standard heater box is similar to this unit.

At first blush, the first version seems nicer in that it allows scat tubing hookup, which would allow heat to be ported wherever you want, even to the eyeball vents on the panel. Of course, this would require a "Y" fitting at the heater box and mixing valves at the eyeball vents (to select between hot & cold).

So I'm debating how important it is to do this. I'm planning on some pretty high, pretty cold flights in my 7, so heat is important. I'm not clear on how effective the heat will be coming right from the base of the firewall with no additional porting around. Has anybody done any mixing of hot and cold air, particularly to the panel eyeball vents? For you guys flying in northern climes in the winter, is this necessary? Or is it better to leave the hottest air by your feet? Has anybody done the scat output? All of this extra stuff is weight and expense. Was it worth the extra firewall penetration & complexity? Any other input?

Thanks in advance,

f1rocket · #2 02-11-2008, 12:56 PM

A couple of points to consider. First is location of your heater box. I would locate it as far up on your firewall as practical. If your exhaust has a CO2 leak, you want to minimize your chances to catching any of that.

Second, I've used both boxes. I used the little triangle box on my RV-6 and I currently use the larger square box on my Rocket. I don't think there's much of a difference really, although I think the square box is a little more rugged. In either case, make sure you use one made of Stainless.

Third, I wouldn't mess with a bunch of hoses and Y-tubes. There's really no need. On both airplanes, the boxes just terminated on the back of the firewall. The warm air circulates pretty well without any additional complexity. I thought a lot about building some ducts out of fiberglass to direct the air to specific places like my feet, upper torso, or back seat passenger but decided to wait until I flew more to see what I really needed. Turns out, it's not needed at all.

My cabin heat (dual heat muffs in series) provides great heat down to about 10 dF. Below that, you might want to consider electric seat heaters in your cushions. I consider this to be my one, single greatest change I added to my Rocket, that I didn't do in my -6.

Noah · #3 02-11-2008, 04:08 PM

Thanks for the response and the photo, Randy. This looks like a different design, unless I'm missing something. The photo seems to show a forward port and a starboard port on the heater box, both located firewall forward. Who made this unit? How is this routed into the cockpit? Why'd you paint it?

Thanks!

f1rocket · #4 02-12-2008, 05:57 AM

That one is a stainless unit from Van's.

There's tube extending through the firewall into the cockpit upon which you can attach a hose if desired.

Mine is painted because all my firewall foreward components are Black, including the engine. Purely cosmetic.

alcladrv · #5 02-12-2008, 09:00 AM

Quote:

Originally Posted by Noah

A good topic for the middle of winter... EMP AV offers several models of stainless firewall mounted heater boxes:
http://www.epm-avcorp.com/ssdiv.html
and Avery sells them too:
https://www.averytools.com/showcateg...setfilter=true

One model allows a scat tubing to be connected aft of the firewall, but requires a separate firewall penetration for the control cable.

The other model does not allow for any kind of scat tubing connection aft of the firewall, but does not require a second penetration for the control cable (the actuating lever is in the middle of the port). The vans standard heater box is similar to this unit.

At first blush, the first version seems nicer in that it allows scat tubing hookup, which would allow heat to be ported wherever you want, even to the eyeball vents on the panel. Of course, this would require a "Y" fitting at the heater box and mixing valves at the eyeball vents (to select between hot & cold).

So I'm debating how important it is to do this. I'm planning on some pretty high, pretty cold flights in my 7, so heat is important. I'm not clear on how effective the heat will be coming right from the base of the firewall with no additional porting around. Has anybody done any mixing of hot and cold air, particularly to the panel eyeball vents? For you guys flying in northern climes in the winter, is this necessary? Or is it better to leave the hottest air by your feet? Has anybody done the scat output? All of this extra stuff is weight and expense. Was it worth the extra firewall penetration & complexity? Any other input?

Thanks in advance,

The stock (Vans FWF kit with 1 heat muff) setup in my -7A puts out adequate heat as long as you've done an above average job of insulating the cabin. I've insulated the sidewalls and floor in the forward cabin and seating area, and sealed the fresh air vents and installed stick boots. There's no insulation in the baggage area, yet.

Yesterday, with a clear sky at noon over Maryland, I was comfortable at 6000' with an OAT of -16F while wearing my flight jacket. When I flew over Pittsburgh at 4500' 30 minutes later, it was -25F and the heater could barely keep up when full open.

Conclusion: More airframe insulation and draft control is better than more heat. Just another data point.

Mike

whifof100ll · #6 02-12-2008, 11:56 AM

I fly an RV-7 that is pretty hot to fly in the summer because the heat valve always leaks some heat even when closed. Is this typical of the heater valve in the FWF kit?

If it is, one thought I had for my RV-6 would be to have another SCAT setup that bypassed the heat muff for summertime ops and route it through the heat muff during winter months. That way I would get additional cool air circulation in summer and heat in winter.

The valve is made to circulate air all the time to prevent damage. Is this to protect the valve itself, or the heat muff?

Pilottonny · #7 02-12-2008, 03:32 PM

Well, I am installing a Vetterman exhaust with mufflers. I had already ordered a hot/cold selector valve from Vans because I wanted to be able to select ?hot? or ?cold? air, not just ?hot? or ?no-hot?!

After discussing this with Larry (Vetterman), I found out that the mufflers need a constant flow of air to cool them, so I will have to install scat-tubing to both of them. One will just dump hot air overboard, the other one will be connected to the heat-box/valve. But this valve can?t b shut off! It will have to dump the hot air, even if the heat is not wanted in the cabin! So it looks like I will not be able to use the ?hot?/ ?cold? air selector, since that will shut-off the airflow when closed. I am still thinking about the perfect solution, because I do want to be able to select cold air during the summer, not just shut-of the hot air! (I guess it will be pretty hot down there, with the hot air probably leaking a tiny bit and the heat coming off the firewall as well)

Anyway, I have not decided yet, but I am tending toward using the hot/cold valve I have and trying to figure out a way to be able to select cold or hot air without closing off the hot air flow from the muffler. Still thinkering though!

Regards, Tonny

Noah · #8 02-12-2008, 03:42 PM

Tony,

What is this hot/cold valve that you are referring to? Do you have a part number and/or photo?

Lars · #9 02-12-2008, 08:18 PM

Quote:

Originally Posted by Pilottonny

Well, I am installing a Vetterman exhaust with mufflers. I had already ordered a hot/cold selector valve from Vans because I wanted to be able to select ?hot? or ?cold? air, not just ?hot? or ?no-hot?!

After discussing this with Larry (Vetterman), I found out that the mufflers need a constant flow of air to cool them, so I will have to install scat-tubing to both of them. One will just dump hot air overboard, the other one will be connected to the heat-box/valve. But this valve can?t b shut off! It will have to dump the hot air, even if the heat is not wanted in the cabin! So it looks like I will not be able to use the ?hot?/ ?cold? air selector, since that will shut-off the airflow when closed. I am still thinking about the perfect solution, because I do want to be able to select cold air during the summer, not just shut-of the hot air! (I guess it will be pretty hot down there, with the hot air probably leaking a tiny bit and the heat coming off the firewall as well)

Anyway, I have not decided yet, but I am tending toward using the hot/cold valve I have and trying to figure out a way to be able to select cold or hot air without closing off the hot air flow from the muffler. Still thinkering though!

Regards, Tonny

Tonny-

While I can't comment on how my system will work since it's still in kit form

I have flown in a couple of RV-6's with Vetterman exhausts and the standard hot-or-no-air Van's heater valve. There was adequate heat in the case of the one that had dual muffs in series. There was also plenty of cold air available to blast in through the panel vents- in fact on one with the leaky plastic eyeballs, there was more than I wanted even when closed. From reading earlier posts on this I think the bigger issue is getting enough hot air, not enough cold air. By the way I bought the EPM-Avcorp all-stainless valve through Avery Tools. Just looked, it's on sale for a few dollars less than I paid (even better for you with the current exchange rate): http://www.averytools.com/pc-158-109...abin-side.aspx

I will be interested to read about your experience with the Vetterman muffled exhaust. That's what I'm planning on using. Less airplane noise = good for the neighbors, even though it's not required yet on these shores.

(thread hijack) Nice part of the world you live in. My sister-in-law lives in Susteren, Nederland. I get over there quite often and have spent many happy vacations in the Ardennes. In fact I think I've driven through Lanaken. (end hijack)

Pilottonny · #10 02-13-2008, 12:19 AM

Noah,

This is it: http://www.vansaircraft.com/cgi-bin/...&product=chv-1

Lars,

The Vetterman exhaust will arrive in a week or so, together with the FWF-kit from Vans (Larry sends it to Vans and for $ 10,- handling charges they pack it in the box with the other stuff.) It will be quite a while yet before I can comment on how well it Works and ?.. I will not be able to compare it to the non-muffled system either.

In the summer when it is hot, I expect it to be very hot near the firewall (feet / legs), although I intend to insulate the firewall. So I guess venting with outside air will make the situation better.

?Thread hijack?: I have a couple of colleagues who live in Susteren, What?s her name? When you are here again, next time, let me know and you can come and have a look at my project. ?End hijack?

Regards, Tonny