I have a 9 year old Bryant 90 Plus Gas Furnace. The hot surface ignitor was replaced today, probably due to the excessive cycling of the equipment. The furnace was locked out and now for the problem. If the temp is 63 in the house and I have the thermostat set at 70, the furnace cycles at least 7 to 10 times to achieve temp. The code is 31, indication is a problem with venting. I verified no restrictions in vent or combustion air with tech on site. He is not sure what the problem could be, and I am no hvac expert. Anyone had this problem before. At least the house is warm again after the cracked ignitor was replaced, but it can't be good to cycle on and off so many times. Thanks for any suggestions. Marty

Temporary jump RH or R and W on the terminal strip. This shoulf cause the furnace to run forever until the jumper is removed. This test will eliminate the thermostat and the thermostat wiring and allow you to isloate the problem. Now if it still cycles it is a furnace problem. Naturally ALL return airs have to be open and ALL registers have to be open for proper furnace operation. Just thought I would mention this fact since many people are closing registers in unused rooms to try to save energy dollars.

Try this: with furnace operating in the heating mode, gently wiggle the wires connected to the pressure switch. If the main burners snuff out & status light starts blinking, the pressure switch is defective. If not, follow other suggestions for code 31 on the service label.

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Originally Posted by hvac1000

Temporary jump RH or R and W on the terminal strip. This shoulf cause the furnace to run forever until the jumper is removed. This test will eliminate the thermostat and the thermostat wiring and allow you to isloate the problem. Now if it still cycles it is a furnace problem. Naturally ALL return airs have to be open and ALL registers have to be open for proper furnace operation. Just thought I would mention this fact since many people are closing registers in unused rooms to try to save energy dollars.

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I will pass on this troubleshooting technique to the tech when they return.

The owner of the business came out on Thursday and had me open all vents in home, remove the inside filters. He rerouted the AC and Furnace drain to get an angle to enable the water to drain more efficiently. He thought maybe the water was backing up, as he has seen this before, there was a lot of water in the lines as the conduit run was slightly higher in elevation than the outlet of the drain where the pipes leave the equipment (although it has been this way since installation). Today I tested the furnace to achieve 5 degrees and the unit shut down 3 or 4 times with code 31 again. Pretty frustrating since even the experts are unaware what the problem is. I have already taken off 2 days of work to allow them to enter the attic and to describe what the symptoms are, even to help verify the vent is clear on the roof, helped with the drain lines, etc. One of the replies I had recently was that maybe the pressure switch is bad. Maybe this is the next part to be replaced. Any other ideas out there would be appreciated.

Here is what code 31 states on my furnace:
Pressure Draft Safeguard Aux Limit Switch(when used) or Blocked Vent Switch(when used) did not close or reopened.

Check for:Proper venting sizing, defective inducer motor, restricted vent, excessive wind, low inducer voltage, defective blower motor or capacitor, defective pressure switch, inadequat combustion air supply, disconnected or obstructed pressure tubing.

If it appears after trial for ignition period, blower will come on for 90 second recycle delay.

Thanks for any replies in advance. Marty

The Carrier repair tech replaced the pressure switch on my furnace but the same problem still exists.
So far, they have spend several hours troubleshooting my issue. Not to sure what else cam be done. All registers open, vent and combustion air lines clear, drain lines relocated for easier draining of water, blower motor tests good, cleaned flame detector, hs ignitor replaced, etc. Any other ideas from the members out there? Could this possibly be a bad circuit board? Thanks, Marty

Did you do the jumper test??

Temporary jump RH or R and W on the terminal strip. This shoulf cause the furnace to run forever until the jumper is removed. This test will eliminate the thermostat and the thermostat wiring and allow you to isloate the problem. Now if it still cycles it is a furnace problem. Naturally ALL return airs have to be open and ALL registers have to be open for proper furnace operation. Just thought I would mention this fact since many people are closing registers in unused rooms to try to save energy dollars.