Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Needing help with propane furnace.

Imminer2
Imminer2 Member Posts: 3
in Gas Heating

My house furnace will only start up with the inducer fan inlet line disconnected at the fan. Once started, it will continue to operate when the line is reattached. I've had the inducer fan inlet and outlet lines cut open, inspected and cleaned, flame sensor replaced, gas valve replaced, inducer fan/motor/capacitor replaced, pressure switch replaced, all tubing checked, condensate pump cleaned and tested. The control board is next. The system is not new. I've had a professional technician work on it and they were not able to find the root cause. Any help would be appreciated.

Comments

  • mattmia2
    mattmia2 Member Posts: 12,777

    tee a monometer in with the pressure switch on the inlet and outlet and see what is happening. which switch does the control say it is faulting on?

    Big Ed_4
  • 109A_5
    109A_5 Member Posts: 2,410

    Make and model of the furnace may help us help you.

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • Imminer2
    Imminer2 Member Posts: 3

    Make and model information: Bryant 90 Plus HVAC system model 350MAV036080 serial number 350MAV036080ADKA. Code 34 ignition proving failure.

    HVACNUT
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 10,489
    edited May 18

    NEW SYSTEM? has it operated properly at any time after installed? This ia a multi position furnace. As a result, the condensate lines may need to be reconfigured to accommodate the removal of condensation from the secondary HX. If not properly configured the pressure switch may not operate when required. You will need to use a manometer in line with the pressure switch tube to see what is happening when the actual failure is happening.

    Or you can just keep shooting the parts cannon and hope for the best.

    Have you paid for these repairs? Did you use a credit card? Perhaps you can dispute the charges. You paid to get the heat operating. It is not operating. You did not get what you paid for. You have a case to have the credit card company charge back the vendor.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • mattmia2
    mattmia2 Member Posts: 12,777

    what were the results of the combustion analysis? what does the flame around the flame rod look like? what were the gas pressures? is the bonding from the burner back to the control good? is the wire to the flame rod good? does the inlet and exhaust piping meet the instructions in the manual?

    the error you are getting is "ignition proving error" so it is locking out because it isn't proving flame. that probably means it is changing how it is burning when you remove the additional resistance of the outside inlet piping. it could be whoever adjusted the combustion didn't do it properly, it could be the gas pressure is low, it could be the content of the gas changed, it could be that the inlet and exhaust piping doesn't follow the instructions.

    EdTheHeaterMan
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 10,489

    Code 34 can be a result of the flame never igniting or it can be that the flame ignited and the sensor did not sense the flame. Can you see if there is a flame or not? Usually the error code would be different if the pressure switch were the problem.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • JUGHNE
    JUGHNE Member Posts: 11,417

    I assume you are talking about the PVC, 2 or 3" inlet.

    Show a picture of the piping of the furnace with the door off please.

  • Imminer2
    Imminer2 Member Posts: 3
    20250520_084437.jpg

    The inlet line is to the left and just above the gas valve. To restate the issue: the system will start up with the line disconnected. Once it starts up I can put it back in place and it will continue to operate.

    Several comments regarding my approach about replacing parts… I found a supplier that accepts free returns with no restocking charge. To date no real expense incurred. I've been doing the work myself.

    I have a replacement control board which I will replace next.

  • SuperTech
    SuperTech Member Posts: 2,585

    That looks like one of the Carrier/Bryant furnaces that are notorious for the secondary heat exchangers failing. I would suggest getting a combustion analysis performed on the furnace before you sink any more money into buying replacement parts for it. It's possible that the parts are doing their job and the faults are an indication of a greater problem with the heat exchanger.

    mattmia2
  • mattmia2
    mattmia2 Member Posts: 12,777
    https://forum.heatinghelp.com/discussion/comment/1855967#Comment_1855967

    Who did the combustion analysis after the gas valve was replaced?

    Look at the flame when the blower starts, there should be no change, if there is the hx is definitely bad. Even if it doesn't is could still be the hx.

  • pedmec
    pedmec Member Posts: 1,210

    You really can't tell a cracked heat exchanger on a 90 plus furnace by looking at the flame. The combustion side of the heat exchanger is in a negative pressure zone so it really just mixes the blower air that is getting into the combustion side with the combustion gases. the one way to tell is if your O2 numbers keep increasing during your combustion analysis. It will keep creeping up when the blower runs.

    mattmia2
  • HVACNUT
    HVACNUT Member Posts: 6,772

    Can you post a pic of the wiring diagram? I can't find one that used the GP relay.

    Screenshot_20250521_061239_Samsung Internet.jpg

    The only diagrams I found show the pressure switch wired directly into the board.

    Does the serial number on the evaporator start 4688? Is it as old as the furnace?

    pecmsg

Categories