I have a 45,000 BTU Bryant hanging propane furnace in garage. I have exhaust venting out at right angle to 6 inch stove pipe from wood burner and then vertical thru roof. I install it several years ago and it worked nice until this winter when barometric pressure would make the fan run constantly with the burners unlit until I push reset button. this is happening at least once a day. what is the cause and what is the remedy? thanks!!!

what does code 31 represent

it could be condensation. or poor seal at roof. probably the seal at roof. also check the larger copper line is it sealed good? if any spot is not this will cause leaking when in cooling mode. maybe dripping from line onto vent.

This is possible, however it is possible they are missing something simple. I hope you can follow along.
1) Is this a Sealed Combustion Furnace, meaning you cannot get to the burners even after you remove the Door Panels?

2) If yes, is this furnace vented with pvc/plastic piping?
3) If yes, do both pipes go outside?
4) If yes then try this.

1) Turn the main power off to the furnace
2) Remove the Door Panel to the burner section.
3) Turn Furnace back and turn the thermostat all the way up.
4)Look into the burner compartment and tell me if the igniter glows red. If it does and the goes out with the burners not coming on.

5) If you feel comfortable or know of someone that is.
6) Turn the furnace off, remove the panel that conceals the burner compartment.

7) Turn the furnace on, if the igniter glows red and the burners ignite. Your problem is in the venting system. Most likely the intake pipe if it goes outside. It could be plugged or something is blocking it. If the burners do not ignite the next thing to make sure that is happening is that the Exhaust blower is operating and you can feel air outside where the pipe terminates. If you it is but no very strong, then your problem could be the inducer motor or to small of vent pipe.

If you could, send me some information about how it starts up
1) Main blower may come on and shut off, make sure the blower runs in on position 1st then back to Auto position. If it does not, you have another problem.

2) The Exhaust blower should come on next
3) About 17secs. later the igniter should glow red.
4) You will here the gas valve make a click
5) The Burners will ignite
6) The flame sensor rod on the far left hand side of the burner will keep the burner lit. If it is dirty the burners will shutdown.
7)About 90secs. later the main blower will come on.

Hi,
Probably your ignitor is bad...

Here is a tip that will help you try to figure out why your furnace is not working.

Basic Furnace or Heating System Troubleshooting

heatman101

Be sure you turned the Control knob from Pilot to ON. Without doing that the heater will not turn. If that's not the problem, the Thermopile may need replacing. Also, check the volume of gas at the heater. It should be a minimum of 5 to 7 water column inches. If it has a wall thermostat, be sure the wires are correctly installed at the heater and the wall thermostat and the it's turned up higher than the ambient air temperature in the garage. If this is an older installation, be sure the exhaust vent piping is not blocked.

If it's operating properly, is T-Stat controlled and is properly vented to the outside, it should be safe to operate all night. I suggest that you set the Wall Thermostat no higher than 50 degrees, though.

It should have a two part chimmney with a 4 inch inner exhaust section and a larger 6 inch outer section that goes over the flange on the top of the furnace. If your existing chimmney does not have this you may have to buy a chimmney kit for a mobile home application.

generally speaking a sealed combustion system is inherently more safe than a system that draws it's combustion air from it's ambient location. however, it cannot be considered 100% safe in a potentially hazardous location. The actual system that would be used in a "code compliant" installation would be a 100% outside air unit.
That being said, you can install this in a garage, the vent that you are referring to (if it is a standard mobile home system) is generally directly above the unit and usually no longer than about five feet. It also requires a listed and labeled termination "cap" If you install 90 degree angles or extend the vent too far you will have issues with condensation in the piping that will cause the pipe/ heat exchanger to fail prematurely.
If the system is a 90+ efficeint unit then the PVC venting is generally allowed to be about 30 feet long, with a 1/4 inch per foot pitch back to the unit for condensation, also the general mfg. instructions allow either 2- 90 degree or 4 45 degree fittings in the line. hope this helps

No, Exhaust vents on heaters should always maintain vertical orientation because heat rises and creates a natural drafting drawing the fumes out. You have a monoxide poisoning situation otherwise.

furnaces must be vented EXACTLY as specified by the mfr or you WILL have problems - they spend a lot of time and money coming up with those specs. then design the furnace based on them.