Heater in the 170 ragwing

Steve · Post by **Steve** » Sun Nov 09, 2003 1:51 am

Ive just bought a 170 ragwing and Ive found the heater is disconected because of the posibility of a backfire in the carbie. As the box is used for carb heat as well and a dept requiment in Australia was to have them blanked of. Is this also the same in America? Is there an "off the shelf" alternative. The aircraft was bought in the north of the country were its allway hot but I live in the south were winter gets quite cold.
regards Steve.

Tom Downey · Post by **Tom Downey** » Sun Nov 09, 2003 6:49 am

Item 110 on the US type certificate authorises the Hanlon And Wilson carb and cabin heaters, they can be purchased from Knisley aircraft exhaust in Loomis Ca. us phone number 1-916-652-5891

Those will bolt right up no problems.

zero.one.victor · Post by **zero.one.victor** » Sun Nov 09, 2003 7:06 am

I don't understand the problem. If the heater (don't know if you refer to carb heat or cabin heat) is disconnected,why can't you just reconnect it? Carb heat & cabin heat should be completely separate--one muffler shroud (heat muff) should be used to provide carb heat to the carberator airbox,the other provides cabin heat to the heat valve mounted on the firewall.

Eric

N2540V · Post by **N2540V** » Sun Nov 09, 2003 3:52 pm

Eric,
Review Figure 47 (Page 86) of the 1948 IPC.
The funny "Y" (Carburetor Heater Union)has the following setup:
Forward connection- Carburetor Air Box
Left and Right side connections - 1 to each muffler
Aft (with flapper valve) cabin heat.

The flapper valve is to stop any backflow.

The altered designed used for your aircraft is used in several aircraft. We installed that on my wife's experimental Avid Magnum.

I do have two spare Carburetor Heater Unions if anybody needs one.
Jim

zero.one.victor · Post by **zero.one.victor** » Tue Nov 11, 2003 5:59 am

Jim,my 170 does have the early (figure 46) cabin heater set-up,but it does not have the "cabin heater union"--which is actually identified by p/n on figure 34 (item 34-83). Like I said,mine has the carb heat suppled by one muff,and the cabin heat supplied by the other-- maybe not per IPC,I now discover,but simpler & therefore better (IMHO).

Eric

Steve · Post by **Steve** » Wed Nov 12, 2003 11:30 pm

Gentlemen this is fasinating but confuseing. I only have one muffler shroud for both carbHeat and heater. Are you saying that it has a devider in the middle? and is it a solid divider or one with some kind of valve. so no blowback can occure? can someone be kind enough to email me a picture if posible as I dont have a manual as yet.
Regards Steve

R COLLINS · Post by **R COLLINS** » Thu Nov 13, 2003 1:44 am

Guys,
My plane has a heater set up for the back seat mounted on the same heat muff as the carb. The system was made by Sorenson's, and has a pull cable through dash with placard that says to close cabin heat before applying carb. heat. Thats to ensure ample air to carb. The front seat is supplied conventionly by a muff on left side of the engine. This has me wondering now because I recently removed the hoses for maintenance and the one to rear seat had been stopped up with aluminum foil and then the hose had been put back on. I discarded this since it was getting close to winter. What is the anomaly with this and carburetor back-firing?
Randal N1745D

mrpibb · Post by **mrpibb** » Thu Nov 13, 2003 4:04 am

Steve,
what I think there trying to say is like my 48 I have a hanlon wilson exhaust system with a shroud around both mufflers, on my left stack the hose goes to the airbox which when closed (no carb heat ) continues to a y on the right side. On the right stack I have a larger shroud around the muffler which also goes to the y adapter. when carb heat is selected the left side supplies the heat to the carb while the right will supplements while still providing heat to the cabin. Keep in mind early 170's like the ragwing
the heat was marginal at best, so cessna had to design a better mousetrap which is evident in the later models. I'd take a picture for you but I sent the system out to knisely during the annual in which the system is not repairable so I got a whole new system coming ( looks like santa's going to be a little cheap this winter

)
I got a question, If you look at your mufflers are they kinda flat? Also know as the pancake mufflers?

zero.one.victor · Post by **zero.one.victor** » Sat Nov 15, 2003 6:55 am

steve wrote:Gentlemen this is fasinating but confuseing. I only have one muffler shroud for both carbHeat and heater. Are you saying that it has a devider in the middle? and is it a solid divider or one with some kind of valve. so no blowback can occure? can someone be kind enough to email me a picture if posible as I dont have a manual as yet.
Regards Steve

Steve,I'm confused--must be cuz you're down under & I'm up over! You say you only have 1 muffler shroud for both carb heat & cabin heat. Do you have one muffler with shroud & one without? Or do you perhaps have a Lycoming or other engine which has only one muffler?

Eric

Steve · Post by **Steve** » Sun Nov 16, 2003 2:47 am

To zero one victor You got it right the first time mate. one manifold with shroud and one without. The firewall now has ownly a blanked off round hole and all the center consule vents have been blanked off and the heater control removed. I dont think the confusion lies with were we live but with out a picture of an original system it is a little bit difficult.
P.S I think I have the ownly rag wing in Austalia Although there are quite a few As and Bs But all of them at least 300 to 400 miles from my loctation so that makes cheching there system difficult.
Regards Steve.

zero.one.victor · Post by **zero.one.victor** » Sun Nov 16, 2003 6:20 am

Sounds like a solution would be simple. First of all,get an Illustrated Parts Catalog for the 1948 ragwing,I think Aircraft Spruce & Univair both sell them. Second,buy a shroud for the muffler that doesn't have one.Third,buy a heat valve that mounts on the firewall,and the cable to control it. Fourth,buy some scat hose & hook it all up. The biggest problem (beside the price of all the parts!) is gonna be finding a shroud to fit the original 1948 pancake (flat) muffler,if that's what you have. A shroud for the later (round) Hanlon-Wilson muffler should be a little easier to find. A suitable heat valve should be easier to find,in fact Aircraft Spruce sells a few different ones but they might be only for experimentals.
You can try some of the aircraft salvage outfits here in the US. I've found that Surprise Valley Aviation (530-279-2111) in California & Specialty Aircraft (800-500-6786) in Oregon to both have a lot of early cessna stuff on hand. There are quite a few others,you can find them advertised in Trade A Plane.

Eric

Steve · Post by **Steve** » Sun Nov 16, 2003 9:13 am

Eric I was thinking along those lines too but the comments of one shroud for both and the Y valve with an anti blowback had me a little confused. My engineer told me it had been disconected in the past because of posssible blowback problems Thank you for the information I think I desperatly need a manual.
Regards Steve.

zero.one.victor · Post by **zero.one.victor** » Sun Nov 16, 2003 4:50 pm

steve wrote:Eric I was thinking along those lines too but the comments of one shroud for both and the Y valve with an anti blowback had me a little confused. My engineer told me it had been disconected in the past because of posssible blowback problems Thank you for the information I think I desperatly need a manual.
Regards Steve.

Yeah,a parts catalog is a huge help in working on these old airplanes. Like I said above,I discovered that my airplane's arrangement of one muff for carb heat & one for cabin heat (completely separate) is not exactly per the book,but is simpler & works well. You might consider hooking yours up in a similar fashion.

Eric