Fixing an unusual cabin heat mod

[hilltop170]

Another viable option for more cabin heat is to find a donor airplane and salvage the later style heat system. Late 170B and all 180 had a better heat valve and firewall header system. The stripped-out 1954 C180 fuselage at Air Salvage of Dallas at Lancaster, TX Airport, KLNC, that I got my baggage door from still had the heat valve and header in place.

1954 C180 firewall with heat valve and header in place

Then if you need the ultimate cabin heater, there is always the Southwind gasoline fired heater which is approved on the TCDS. You will never be cold again.

Southwind heater installed under the rear seat

[bagarre]

My vote is for the late model heater.

IMG_0046.jpg

[gfeher]

I had a chance to get to my hangar today so here are the measurements. On my left horizontal front baffle, the center of the original cabin heat opening is 2 1/2 inches outboard of the inboard edge and 2 inches aft of the forward edge, measured perpendicular from the respective edge to the center of the opening. The following pics illustrate the measurements. They are taken from the top -- left is inboard. (Although I snapped the pics from the top, I actually took the measurements from the bottom side to be more accurate, as the scoop is in the way on the top.) The pics are really just to show how I took each measurement perpendicular to its respective edge, as the intersecting edges are not square. (I hope that's clear.) Ignore the other opening. It was for my cabin heat after the original cabin heat opening was used for alternator cooling. I cut a similar opening in my new Airforms baffle and moved the bottom flange from that opening to my new one.

Photo 1

Photo 2

[gfeher]

David, I've always been in interested in your heater plenum mod in this thread:
http://www.cessna170.org/forums/viewtop ... ior+heater

You said that you didn't need to change the butterfly control valve.

How much of an improvement did you get with it? And any idea how it compared to the '53 and later heating?

[n2582d]

3. According to my research Cessna did use a 3" firewall mounted heat valve, which looked exactly like the 170 2" version and I believe interchangeable. I never came across one but didn't look hard cause I needed that funnel in #2.

Bruce,
In looking at the C-150 IPCs Cessna tried everything under the sun with heater valve setups. The 150G and 150H (1967-68) models had the 3" firewall valve. A cursory check of part numbers does seem to indicate that the rest of the valve is the same making this 3" valve cover interchangeable with the early 170 valve. The p/n for the 3" cover is 0450248-1. (The entire valve assembly is p/n 0450247-2). Probably cheaper just to rivet on an A/C Spruce 3" flange to the existing cover. The hardest part to a conversion might be modifying the heat muff shroud for the 3" duct.

150heater.jpg (46.11 KiB) Viewed 14318 times

David - Firewall looks great! Appears you're making good progress.

[bagarre]

David, I've always been in interested in your heater plenum mod in this thread:
http://www.cessna170.org/forums/viewtop ... ior+heater

You said that you didn't need to change the butterfly control valve.

How much of an improvement did you get with it? And any idea how it compared to the '53 and later heating?

It made a significant difference in heat distribution. I've never flown in a '53 or later types in cold temps to compare. It was worth the effort as an afternoon project to improve heat. Upgrading the whole shebang to '53 is a lot of work and cost. This set me back a few feet of aluminum, rivets and nutplates. We made it out of .035 as that was all we had on hand but .020 would be more than sufficient.

In my latest project, I replaced the firewall so I opted to go all out.

[brianm]

Thanks Gene, the measurements are really helpful.

[Bruce Fenstermacher]

Gary that is great info to document here. An intermediary step to a complete 3" scat upgrade would be 3" from the Y on those still running pancakes like me or those running the Y still that shouldn't. This should give improvement cause the 3" would be feed by two 2" tubes unless carb heat is one.

As for those with the correct right Hanlon-Wilson muffler who want to upgrade AND can come up with the funnel front. The muffler shroud and the V tail end could be manufactured by a decent sheet metal guy. The right muffler could be modified by cutting of the flange for and aft that holds and seals the ends of the original baffle. You'd also need a 3" flange to replace the 2" in the front engine baffle.

[edbooth]

Another viable option for more cabin heat is to find a donor airplane and salvage the later style heat system. Late 170B and all 180 had a better heat valve and firewall header system. The stripped-out 1954 C180 fuselage at Air Salvage of Dallas at Lancaster, TX Airport, KLNC, that I got my baggage door from still had the heat valve and header in place.

6E319E9B-5928-45E6-A136-C57A7D6B8460.jpeg

Then if you need the ultimate cabin heater, there is always the Southwind gasoline fired heater which is approved on the TCDS. You will never be cold again.

2C1779CD-6341-4377-A224-C880FEEDDD38.jpeg

I have seen several of these, but personally I would feel very uncomfortable with a gasoline fire under my back seat... The heater in our 53 has been fairly adequate. Most of the cold air would come from the back and out from under the back seat. Something to block that draft helped a lot.

[GAHorn]

As Bruce points out, the '53 and later airplanes had a MUCH better cabin heater/ventilation system. (It's one of the first things pointed out to me by Assoc'n Members who were advising me when I was searching for a 170 to own.) And Bruce also mentions the right-side muffler issues that are involved with that better system.

The RIGHT side muffler of the '53 and later airplanes (SNs AFTER 25372) is a DIFFERENT MUFFLER than previous Hanlon Wilson systems, and it also used different heat-shroud, Inlet and Outlets. This can also be an issue with any EARLY CONVERSIONS from Pancake to H-W systems because the CONVERSION for those early airplanes uses TWO LEFT MUFFLERS and shrouds. This means that even if one were to convert from Pancake to H-W ...one would still only have 2" hoses supplying the cabin heat.
WHY did the conversion kit designed by Cessna use two LEFT mufflers?... I suspect it was so the owner would not also have to deal with converting that cabin heat system at the same time. Of course that philosophy also locks those owners into that early cabin heater. That makes a cabin heater conversion to the later system doubly-expensive, because one would then be forced to go back and re-convert their right-hand muffler (which is actualy a left-hand being used on the right side) to the later right-hand muffler.

Soooo.... If you are converting a Pancake to a H-W exhaust system.... one might wish to also consider whether one also wants better cabin heat...and IF SO, then one would want the later right-hand muffler, shroud, and Inlet/Outlets to take advantage of the 3" distribution system (which also involves reconfiguring your firewall cabin heater valve, and maybe your interior distribution ducts.... equaling a LOT of work....after which you'd be faced with how to get it approved since that late right hand muffler is not approved for pancake conversions.)

Ed Booth makes a good observation in that a lot of improvement to cabin comfort can be made by sealing-off cold air leaking into the cabin. A lot of it comes forward from the aft fuselage. The area behind/above the hat-rack is usually wide-open as is that area beneath the floorboards and both allow cold air to come forward into the cabin. I used a flat-sheet of 2024 cut to shape and PK-screwed it to the upper/aft side of Station 108 bulkhead (item 29 in the depiction) above/behind the hat-shelf only, to stop that cold air. It not only strengthens that area and prevents objects on the shelf from travelling aft past the headliner, but it also got rid of the noise emanating from the rear fuselage when taxying and stopped any cold air (and engine exhaust) from travelling to the cabin thru the tailcone. (It's amazing the oil-canning and cable-slapping that goes on back there which can be heard if you remove your headset and sit in the back seat while taxying. Closing that bulkhead stopped that.)

[lowNslow]

....after which you'd be faced with how to get it approved since that late right hand muffler is not approved for pancake conversions.)

(Insert Blue Elder comment here.)

[GAHorn]

....after which you'd be faced with how to get it approved since that late right hand muffler is not approved for pancake conversions.)

(Insert Blue Elder comment here.)

[hilltop170]

3" tubing would be great but even 2" using the header above the rudders is plenty adequate. The cabin stays comfortable down to about zero, that's as cold as I have flown the 170 since the conversion, and mine has 2".

[Bruce Fenstermacher]

3" tubing would be great but even 2" using the header above the rudders is plenty adequate. The cabin stays comfortable down to about zero, that's as cold as I have flown the 170 since the conversion, and mine has 2".

Some how cabin heat advice from a guy flying in Texas doesn't have the same weight as advice from a guy flying in Minnesota. Of couse if your running those shinny winterszation plates, at least the other guys in Texas might listen closer.

[cessna170bdriver]

3" tubing would be great but even 2" using the header above the rudders is plenty adequate. The cabin stays comfortable down to about zero, that's as cold as I have flown the 170 since the conversion, and mine has 2".

Some how cabin heat advice from a guy flying in Texas doesn't have the same weight as advice from a guy flying in Minnesota. Of couse if your running those shinny winterszation plates, at least the other guys in Texas might listen closer.

Don't forget that Richard also flies in Alaska...