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01-18-2011, 12:08 PM
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#1
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Bus Crazy
Join Date: Nov 2007
Location: vancouver island bc
Posts: 1,028
Year: 1965
Coachwork: thomas
Chassis: chevy
Engine: 350
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furnace qs
hey guys and gals ive hooked up my furnace,it has 4 wires coming out of it,2 blue for the thermostat and a red for + and yellow for -.So thats what i did odd that the thermo has 2 blues and has a black and white coming out of it.Anyways hooked it up and nuthin.Think I should turn the thermostat wirea around will that make a diff? Also do you fuse your furnace? 12v...On the bright side the fridge is working fine so I can sit by the fire and drink beer if it all goes to hell!Do you guys fuse yer fridge from the battery? cant have that failing...... anybody know if these have fuses in them? This is a typical rv furnace,i think suburban
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01-18-2011, 03:22 PM
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#2
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Bus Geek
Join Date: Jun 2004
Location: Roswell, NM
Posts: 3,588
Year: 1986
Coachwork: BlueBird
Chassis: 40 ft All American FE
Engine: 8.2LTA Fuel Pincher DD V8
Rated Cap: 89
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Re: furnace qs
You need to look at your installation instructions. My suburban is really old. Probably almost as old as my 30+ year old RV. So I'm not sure if this will help you. If not let me know and I will find the troubleshooting links for the suburban furnaces that I have booked maked on the computer.
From my furnace. I have two blue wires, a red, a yellow. One of the blue wires comes out of the same connection as the red wire.
The blue wire that comes out with the red wire is connected the lightweight wire (red) which goes to the mechanical thermostat (yellow wire at top left hand side of thermostat in pic). The other blue wire goes to the white wire that runs to the thermostat (ground screw at bottom left hand side of thermostat pic). The red wire goes to the blue RV 12vDC (+) wire and the yellow wire goes to the white RV 12vDC (-)
I have a White-Rodger brand thermostat that is a Heat Only mechanical thermostat (I think I bought the thermostat in GA at Home Depot but not sure). We did replace the older thermostat because it wasn't working right.
Our furnace was working great until we headed down to TX (Nov 2009) I blew a rear outside tire (I have rear duallys on the Class C) that was under the furnace. Got the tire fixed and headed on down the road. Got to TX and the furnace wasn't working. We halfheartedly fiddled with it over that winter but really wasn't that into getting it fixed because the electric heat was cheaper than the propane. Once we got back to NM, we tore into the furnace (pulled it completely out of the RV). I was in need of a good cleaning so we did that. Turned out the flat tire beat the wheel well that the furnace sits on hard enough to beat rust that was inside the tubing loose and the little flecks of rust was blocking the orifice to the burner. The furnace would try to light but it would go right back out. Now it works great again. But we only use it as a back up to the electric heater since our electric is included in our site rental.
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01-18-2011, 04:30 PM
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#3
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Skoolie
Join Date: Aug 2009
Posts: 187
Year: 1963
Coachwork: Grumman
Chassis: Chevrolet
Engine: Chevy 292 I-6
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Re: furnace qs
I was able to find a manual for my old furnace after a bit of searching.
If your furnace is like mine, 2 wires will come from a photoelectric eye that generates a voltage when the pilot light is lit. One side voltage is sent to the thermostat which switches it on/ off according to the temperature setting. The other wire from the PE eye goes to the gas valve. When the circuit is complete, the gas valve opens and the furnace heats.
The other wires may be for a manual "fan only" switch. Mine doesnt have that, but does have a 12VDC/120VAC selector for the fan power.
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01-18-2011, 04:49 PM
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#4
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Bus Geek
Join Date: Jun 2004
Location: Roswell, NM
Posts: 3,588
Year: 1986
Coachwork: BlueBird
Chassis: 40 ft All American FE
Engine: 8.2LTA Fuel Pincher DD V8
Rated Cap: 89
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Re: furnace qs
I have a thermocouple. IF it was replaced when a previous owner replaced the AC unit, then my furnace could be as new as 1984. When I said my furnace is old, I really meant it!
http://bryantrv.com/docs.html Lots of old manuals for RV appliances, heaters, etc.
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01-19-2011, 12:34 AM
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#5
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Bus Crazy
Join Date: Nov 2007
Location: vancouver island bc
Posts: 1,028
Year: 1965
Coachwork: thomas
Chassis: chevy
Engine: 350
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Re: furnace qs
thanks very much gang i can hear it clicking down there when i turn on the stat but nuthin else. besides the neg(yellow) and +(RED) only 2 blus and they are both headin to the thermostat.Ill muck about tomorrow and if nuthin i guess ill pull it out.argh! Im gonna look for my manual online
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01-19-2011, 08:45 PM
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#6
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Bus Geek
Join Date: Jun 2004
Location: Roswell, NM
Posts: 3,588
Year: 1986
Coachwork: BlueBird
Chassis: 40 ft All American FE
Engine: 8.2LTA Fuel Pincher DD V8
Rated Cap: 89
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Re: furnace qs
So you hear it sparking but no ignition? Did you have it working? What has happened since it was last operating? Have you pulled the burner tube out and cleaned it ? Getting it back in is a PITA as you have to turn it about a quarter turn or so just right and the straighten it back up just to get it replaced. Have you cleaned the contacts? What does your igniter look like?
When you trip the thermostat, the blower kicks on. Then the sparking (clicking) starts. It should be a very rapid ticking sound. The ticking stops and then the blower shuts down. Is that what's happening?
Let me know. Tomorrow (when it's daylight) I can take some pics and post them on my photobucket page and pm you thru here if you want.
Most of the time it's mostly cleaning. We have cleaned our burner/igniter every fall before having to crank it up. I generally clean out a dead spider or wasp. I can take pics and post them on how we clean it.
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01-20-2011, 01:29 AM
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#7
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Bus Crazy
Join Date: Nov 2007
Location: vancouver island bc
Posts: 1,028
Year: 1965
Coachwork: thomas
Chassis: chevy
Engine: 350
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Re: furnace qs
no sparking just a click down ther im gonna pull it out again and have a look ill post pics you knoe how it goes worked when opulled..i want this type heater cause it draws fresh air in and exhaust outside as you know my bus is full of wood so besides electric i dont want to run unvented heat.pull,service,make good reinstall.thanx!
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01-20-2011, 06:15 AM
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#8
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Bus Crazy
Join Date: Nov 2010
Location: Andrews,Indiana
Posts: 2,458
Year: 1991
Coachwork: Bluebird
Chassis: AARE
Engine: 3116 Cat 250hp
Rated Cap: Just the two of us.
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Re: furnace qs
Since no one has answered the 12v question, yes you should fuse them. More or less everything should be fused. It's better to blow a fuse than see your appliance let the smoke out and quit working, or your whole bus go up in flames.
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01-20-2011, 07:01 AM
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#9
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Skoolie
Join Date: Aug 2009
Posts: 187
Year: 1963
Coachwork: Grumman
Chassis: Chevrolet
Engine: Chevy 292 I-6
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Re: furnace qs
Is your system lit by a pilot light, or a spark ignitor?
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01-20-2011, 11:49 AM
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#10
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Bus Geek
Join Date: Jun 2004
Location: Roswell, NM
Posts: 3,588
Year: 1986
Coachwork: BlueBird
Chassis: 40 ft All American FE
Engine: 8.2LTA Fuel Pincher DD V8
Rated Cap: 89
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Re: furnace qs
Spark Ignitor on mine. You may need to clean your spark ignitor if you have one. A light sanding is all you need (I use a 220 fine Sandpaper or the fine side of a nail file). Do not try to force the contacts closer together. Lightly sand the exterior connections to the ignitor as well. If spark, make sure the ceramic isn't cracked. Next thing pull your burner tube out and Use a straightened paper clip or similar thin wire to clean out the little honeycomb metal in the burner. Tap it gently on a hard surface and then dump the junk out the rear of the tube. Replce and try again. If that doesn't work, then you need to pull your furnace. Remove the gas pipe (wraps from the side around to the back) make sure the tube is emptied of junk. Check the orifice the tube hooks into at the rear of the furnace. make sure it is clean and no rust. While you have it pulled out, get one of those swiffer duster things and dust the interior of the burn chamber. Dusting will brush any soot that may have accumulated along with any little buggy carcasses. Make sure the gas lines are all free of debris and put back together. re install and try again. It may take 3 or 4 tries to get all the air out of the lines and the LP flowing good. If still no go... then you may have a bad circuit board (you can take a peek at the the board while the furnace is pulled out. It is on the side where the gas line enters the furnace. We popped ours out and flipped it over to look to see if there was any cracks or "hot" spots on the board.
Pics will be here when I get them up
http://s570.photobucket.com/albums/s...nske/Our%20RV/
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01-20-2011, 12:43 PM
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#11
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Bus Geek
Join Date: Jun 2004
Location: Roswell, NM
Posts: 3,588
Year: 1986
Coachwork: BlueBird
Chassis: 40 ft All American FE
Engine: 8.2LTA Fuel Pincher DD V8
Rated Cap: 89
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Re: furnace qs
Pics are up. Hope it helps.
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01-20-2011, 05:29 PM
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#12
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Bus Geek
Join Date: Jun 2004
Location: Roswell, NM
Posts: 3,588
Year: 1986
Coachwork: BlueBird
Chassis: 40 ft All American FE
Engine: 8.2LTA Fuel Pincher DD V8
Rated Cap: 89
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Re: furnace qs
I used a soft small paint brush to brush the rust dust off the orifice on our furnace. As for the term "igniter". I'm not sure of the correct name but it's the thingy that makes the sparky thing that lights the metal thingy that the LP comes out of. Now which makes more sense? My previous post or this one? And if you say this one Smitty, It will be proof positive that you have been in the cold too long!
The wire is to clean the honeycomb metal in the burner
This is my "sparky thingy"
The pics are in one of my photobucket albums. I did not want to post them all here. A little more info is on the pics under "description".
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01-20-2011, 11:38 PM
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#13
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Bus Geek
Join Date: Jun 2004
Location: Roswell, NM
Posts: 3,588
Year: 1986
Coachwork: BlueBird
Chassis: 40 ft All American FE
Engine: 8.2LTA Fuel Pincher DD V8
Rated Cap: 89
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Re: furnace qs
Quote:
Originally Posted by Smitty
... They do some funky stuff in RVs
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Oh yes they do! Drives us nuts. It's a short trip.
Quote:
Originally Posted by Smitty
... Matter of fact, from best I can tell from your pics, your furnace doesn't have a pilot light, does it?
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No, the furnace does not have a pilot light. While I have no problems with LP and have cooked/heated with LP for most of my life, I do not like pilot lights. To me, LP is not dangerous, but PILOT LIGHTS are. Happily, my furnace is direct spark which was dumb luck... just like after we painted the interior of the RV blue, yellow with white trim, the awning (with a metal weather shield) was unrolled to reveal... blue, yellow and white stripes! Which just reinforced my daughters decision that I am a witch (lots of coincidences in my life... and they think I can read their minds ). We replaced the water heater with one that has a direct spark. and of course the RV range has no pilot light on cooktop but the oven does (which I turn on and light the pilot when ever I have to use the oven). My oven for the bus, which is sitting inside the bus right now... it was my oven from home, has no pilot light (piezo-electric). Requires 110vAC to light the oven but if need be, I can light the cooktop with a match (handy during a power outage).
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01-27-2011, 03:36 PM
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#14
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Bus Crazy
Join Date: May 2010
Location: Farmington Hills, Mi (Detroit area)
Posts: 1,968
Year: 2000
Coachwork: Eldorado Aerotech 24'
Chassis: Ford E-450 Cutaway Bus
Engine: 7.3L Powerstroke
Rated Cap: 19
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Re: furnace qs
Sounds like you're not getting propane into the combustion chamber.
I had a similar problem with an Atwood Everset Star furnace recently. When bench testing it, I could hear the fan running then, a few seconds later would hear the snap, snap, snap of the spark ignitor working. No heat though. Turned out there are two solenoid coils on the front of the gas valve and one was bad so the gas valve wouldn't open. I'm assuming you've actually got propane in the tank and the regulator is working properly. To test that, take the tank outside and open the valve a bit. You should hear a low hiss and be able to smell the propane gas.
You don't mention which furnace you have but on the atwood there are two black, cylindrical parts on the lower front of the gas valve (solenoids). There are wires attached to both of the soleniods and if one solenoid is bad the valve won't open. To test the solenoids unhook the wires (marking where each goes) and check both with an volt meter set on continuity. If one is open (no continuty) there's your problem.
The newer furnaces have a computer board that controls the combustion process. In general, if you hear the ignitor snapping you can be fairly sure that everything up to that point is OK. I.E. you have 12v power, the t-stat is calling for heat, the combustion fan is working, the PC board is OK, and the ignitor is working. The snapping sound you hear is the spark jumping across the electrodes.
What should be happening after the ignitor snaps is 1) propane gas ignites 2) the flame sensor signals a good flame and 3) the high limit sensor reports combustion chamber temps are within range.
From what you've said, I'm betting on the gas valve as the culprit.
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01-27-2011, 08:53 PM
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#15
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Bus Crazy
Join Date: May 2010
Location: Farmington Hills, Mi (Detroit area)
Posts: 1,968
Year: 2000
Coachwork: Eldorado Aerotech 24'
Chassis: Ford E-450 Cutaway Bus
Engine: 7.3L Powerstroke
Rated Cap: 19
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Re: furnace qs
Quote:
Not exactly, it's simply a switch that opens on a temp rise (overheat) to cut-off the gas valve (burner). This prevents a burner from continuing to burn in the event of say a blower motor failure, and the furnace going into melt-down.
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Picky, picky, picky (but accurate).
BTW Smitty, great catch on your recent battery connections post.
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