Duchess Janitrol Heater (Bunson Burner)

rdsoxpilot

rdsoxpilot

Well-Known Member
So if anyone's flown the Duchess you'd remember the sequence you've gotta do for the heater controls.

Question is: When you have the cabin air full blast, the heater going & everything... is there a flow control valve that limits how much fuel goes into the janitrol system when you move the actual heater knob. Or does it come in at a constant rate, and the heater knob you move just controls the mixture of hot/cold air..?

Thanks in advance-
:beer:
 
From my days flying Seminoles with Janitrol heaters, I remember it being the latter rather than the former. Man, those things had enough umph to cook a christmas ham, watch out! :laff:
 
Old Dominion Flyer said:
From my days flying Seminoles with Janitrol heaters, I remember it being the latter rather than the former. Man, those things had enough umph to cook a christmas ham, watch out! :laff:
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:yeahthat: Been a while for me too, but I think it was a constant flow at .5 gph off the left tank. There was no way to change it.
 
shdw said:
:yeahthat: Been a while for me too, but I think it was a constant flow at .5 gph off the left tank. There was no way to change it.
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It's 3/4 gph off the right tank. at least in ours it is, don't remember what the seminole burns.

And yea, we made some scrambled eggs this morning enroute to akron, kinda overcooked em though.
 
the fuel burn rate..is based on full blast, and thats how it should be figured for fuel calculations. If you have it on a lower setting you will find it uses less.The regulator and temp switches within the system turn the fuel on and off as the temp in the combustion chamber changes. If its really cold out the "flame thrower" will be working more to keep constant temp. If it isnt too bad out, it will "fire"up less, and use less fuel. Remember..they are all about CYA on the published numbers.
 
jeepthrills said:
the fuel burn rate..is based on full blast.
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At least in the seminole, there is no such thing as not full blast. It runs at a set speed, the flame that is. You control where the warm air is directed, not the intensity of the flame.
 
seminole:

top lever: amount of air
second lever: temp
bottom lever: defrost or floor

its been a while..but do you agree with that?

if the second lever is more to the right...then more heat ie, the flame will run more often to maintain output temp (constant OAT)
if it is more to the left you are telling it i dont want such a high cabin temp, so it will run less often.

I agree you are not changing the intensity of the flame, just how often the flame is on.
 
The baron as the same system and I use .5/hr of fuel use out of the left tank. So every ten flight hours I add 5 additional gallons to the left tank to even it out. And no, that heater does not keep up in the baron. I honestly think that there it has issues with the higher speeds (180+ knots). After about 200 knots at an OAT of -15 to -18C it has trouble keeping up and in about 15 mins will be cold inside the airplane. (*take with a grain of salt because I fly a cargo aircraft not a passenger one*)
 
jeepthrills said:
just how often the flame is on.
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No:

POH 7-30: Operation of the combustion heater is controlled by a three-position switch located on the instrument panel and labeled CABIN HEAT-FAN.

You are right about the other three levers. But it doesn't turn itself on and off automatically with the temp control. It is either on and at .5 gph or it is off and at 0. You can turn off burner by putting it on off or on fan. But when it is on the "cabin heat" selection it is a constant flame regardless of the other 3 levers.

PS it is 0.5 gph out of the left tank. I have no clue how I remembered that.
 
Some of the new heaters actually do the on/off/on flame now. Had a mechanic tell me that in the fall when they replaced a heater on one of the barons that I fly.
 
braunpilot said:
Some of the new heaters actually do the on/off/on flame now. Had a mechanic tell me that in the fall when they replaced a heater on one of the barons that I fly.
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I will have to research that, I am unfamiliar. Do you know if it uses a pilot light? I thought I remembered seeing something with regards to them not going on and off because of the wear to the starting system.
 
http://www.kellyaerospace.com/articles/Heater_AMT.pdf
page 2 left side half way down

Temperature control in the cabin is
maintained by the adjustment of a duct
switch. Besides the duct switch inputs,
temperature control in the heater
includes a cycling switch and an overheat
switch. The cycling switch maintains
optimum combustion temperatures​

by controlling the fuel solenoid.
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no pilot light..a sparkplug! And it will carbon foul just like the ones in your piston engine. The link above should answer alot of questions about gasoline powered aircraft heaters.
 
no worries!!

I made sure all of my multi commercial students had a copy of that before their systems stage check. Helps a bit with the theory and understanding.

remember you cant teach it, if you dont understand it yourself:D
 
great stuff jeepthrills. thanks for putting that up, no clue it ran on a spark plug.

pretty sure on the duchess it's a pilot light.. when our heater overheats again (prob tomorrow) i'll check for it.
 
shdw said:
Sweet, thank you. Wonder why our crappy seminoles didn't have this. Maybe .5/hr just doesn't warrant the cost of a more complex system.
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Seminoles need it for sure, those things are soooo hot I think it would heat my house!!
 
rdsoxpilot said:
great stuff jeepthrills. thanks for putting that up, no clue it ran on a spark plug.

pretty sure on the duchess it's a pilot light.. when our heater overheats again (prob tomorrow) i'll check for it.
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Nope, spark plug.
 
Roger said:
Nope, spark plug.
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exactly right. checked it this morning and sure enough there it was.

it kept on popping the reset switch in the back, and we got the dredded orange heater overheat light in the pit. getting it looked at now.
 
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