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Problem: Furnace main burner ignites, the main burner stays on for 8 to 10 seconds, then shuts right back off

Problem: Your furnace main burner ignites, the main burner stays on for 8 to 10 seconds, then shuts right back off. Your furnace tries this ignition sequence again, and the same thing happens. After 3 times the furnace goes into lock out, and the only way to get it out of lock out is to turn the power switch off and on. Everything starts over again without ignition of your gas burners.

Solution: First, turn off the power to your furnace. Check all wires and ground wires to make sure they have good tight connections and are not burnt. Next, remove the screw or screws that hold your flame sensor in. Please do not confuse the flame sensor with an Ignitor. We do not want to touch the ignitor at all. If you touch an ignitor it will shorten the life of the ignitor or it will break. Below this paragraph we have a picture comparing an ignitor with a flame sensor. Clean your flame sensor with steel wool or emery cloth (fine sand paper). You might need a new flame sensor, but most of the time they can be cleaned and your furnace will work well after cleaning. I have seen flame sensor go out. Most of the time when they go out the white porcelain is cracked. You might want to have a spare flame sensor on hand. Here is a link to our Flame Sensors Page: Please click hear to go to our Flame Sensors Page or you can click on the flame sensor picture below. Near the bottom of this page we have a YouTube video on how to troubleshoot, clean and change-out a flame sensor.

Thanks! We would Love to Have Your Business!

Below is a picture to help you identify what a flame sensor looks like and what an ignitor looks like. Below is a picture comparing flame sensors on the top with an ignitor on the bottom. We do not want to touch the gray glass part of the ignitor or it will shorten the ignitor’s life or it might break.


flame sensor

Please click here to go to our furnace ignitors page.

Below we have a YouTube Video on how to troubleshoot and clean a flame sensor:

54 thoughts on “Problem: Furnace main burner ignites, the main burner stays on for 8 to 10 seconds, then shuts right back off

  1. Hi Steve.

    We have a 10 year old Pennco model 15045 Series boiler. It provides supplemental baseboard heat to our basement. The boiler has an intermittent (spark) type pilot ignition system, a UT 1003-600A controller and a Honeywell VR8204H1006 valve.

    The problem started about a month ago. When the thermostat calls for heat, the igniter sparks and the pilot ignites after a second or two. The main burners ignite for several seconds before the main and pilot valves drop out.

    Thinking bad flame sensor I replaced the combined pilot / igniter / sense unit.
    The problem persisted.
    I discovered the problem is with the pilot flame not reaching the flame sense after main burner ignition – and – it happens only when the inspection covers are in place. If I remove the inspection covers the pilot remains lit and the boiler will run until the thermostat stops calling for heat.

    Further investigation shows that the with inspection covers in place, the majority of the combustion air enters the firebox through an opening in the lower right corner of the inspection plate. This opening is used for the blowback switch. The concentrated air flow through this opening is enough to pull the pilot flame away from the sense probe. The pilot appears to remain lit on the opposite side (the main burner side). The controller, sensing loss of pilot, shuts off the main and pilot valves.


    1. Hi Pat! I am sorry, I am not very familiar with boilers. If the flame on the pilot is being blown off target I would like to suggest that you clean the heat exchanger and vent to make sure the heat exchanger and vent or unobstructed. Please make sure the boiler is venting properly. I know that a stopped up or leaking heat exchanger will cause the furnace burners to light properly then after 5 or so seconds the burners will start burning back (not burning at all on part of the burner) causing raw gas to enter the heat exchanger, soot the heat exchanger up and cause more restriction in the venting of the furnace. The pilot should burn straight up if the vent and heat exchanger are not blocked. Best of luck in finding and correcting the problem. Steve

  2. My gas furnace (don’t know make/model… i’m at work!) has been having cycling issues, and three repair techs later, I am told that it needs a new circuit board, or I need to replace the entire system. I am curious because the first tech did some routine maintenance (change the filter, cleaned the flame ignitor), tested the voltage, temperature of the air flow, and then he skipped off with my $104 “diagnostic” fee (on top of my service contract). The second tech did some of the same things, tightened up some connections, and skipped off without charging anything (3 days after the first tech), but advised me that the thermostat would need to be changed because it doesn’t go with the furnace I have (the thermostat came with the house when I bought it 10 years ago, so maybe that’s true…?). The third tech gave me the bad circuit board/replacement news (2nd and 3rd tech, same tech). He said that he left the house with “some heat, but not much” and that he would get some numbers for me from his home office and contact me tomorrow for financing options.
    I’m not sure I can trust the 2nd/3rd tech… would it be possible that the thermostat does need to be replaced, since my dual stage furnace seems to be igniting and staying on for a good while? I’m not sure when it ‘craps out’, but the house goes from being warm to fairly freaking cold in an overnight situation when it is 20 degrees out… i’m in the Atlanta area. Love to have your advice on this before I commit to a furnace replacement. Thanks!

    1. Hi Karen! Sorry that you are having trouble with your furnace. The only reason why I would recommend replacing a furnace would be if the heat exchanger is cracked of if the furnace presents a dangerous condition to the home owner. I would suggest replacing the flame sensor. Sometimes just cleaning the flame sensor does not fix the problem. Most of the time when furnaces have trouble lighting is when they are cooled down and cold. So maybe during the middle of the night the furnace or flame sensor cools down and does not sense the flame then this sends the furnace into lock out mode until the switch on the side is reset. The next time the furnace goes out please reset the on/off switch on the side of the furnace and watch to see if the furnace lights or not. It would not hurt to replace the thermostat. Most of the time when a furnace messes up there will be a blinking code on the control board that tells what problem the furnace is having. Most of the time what the blink code means is located inside the furnace blower door on a label or somewhere on the furnace. The next time your furnace messes up I would suggest trying to read the blink code on the control board. Most of the time furnace manufacturers will place a viewing window in the furnace blower door so you can see the blinks. It sounds like you have a real nice two stage furnace. Most of these high efficiency furnaces have at least a 20 year heat exchanger warranty and most have a life time warranty. I would hate for you to waste your money on a new furnace when you really do not need one. If you would like for me to look up parts please send your furnace’s model number. If it is a Bryant or Carrier I will need the product number. Best of luck! Steve

      1. Steve,
        Thanks so much for your prompt response, and for helping those of us who are not literate in the world of heating and cooling! The process of just reviewing your Q&A sessions makes me feel much smarter about HVAC – a great help to all who come here, I am sure. I am scheduled to be home this weekend, so I will take a look at the furnace and troubleshoot as you have suggested. My parents are living with me, so they are dealing with the weekday cold front, but hopefully the electric heaters will get them through until I can arrive.

        Thanks again, and I will certainly come back to report what I have found. Have a great day!

      2. Hi! If the code flashes are right then it sounds like the furnace is over-heating and going off on limit. This can be caused by a dirty air filter, dirty or stopped up AC evaporator coil, slow blower motor (might need a new capacitor), or a furnace that has too much gas input or pressure (might need to adjust gas valve). Below is a parts list for your furnace model. Here is what I found when I searched for the control board part number online: Tech seems to think the circuit board is dropping the draft inducer out. So he thinks it is the circuit board sounds like to me. If he suggests the dual stage thermostat then I would probably go with the two stage even though most two stage furnaces will work on a one stage thermostat and allow the circuit board to determine after running in low stage heat to kick into high stage heat after 10 minutes. I hope the tech can get it fixed without anymore expense. Steve
        Total: 77 Parts Model#: GUIV115CX50 Mfg#: P1230207F
        Part Number Description Type Substitution
        A4568804 GROMMET-D
        B1370818 INTERLOCK SWITCH 0130M00243
        B1392104 UNIVERSAL BUSHING UB 875
        B1410310 PRESSURE SWITCH HOSE B1410310Q
        C6121806 BLOWER CUT-OFF
        C6349703 TRANSFORMER F
        C9443701 MOTOR MOUNT BRACKET R9900181
        D6723303S BLOWER WHEEL F
        M0221461 TC SCREW
        M0282015 KEPS NUT
        0151F00000P GAS VALVE – WHITE-RODGERS 2-STAGE F 0151F00000PS
        0231K00013A MOTOR 3/4 HP PROGRAMMED F
        10568804 MANIFOLD OBSOLETE
        10690002 DOOR CATCH ASSY
        10690301 FILTER ANGLE OBSOLETE
        10716003 ORIFICE F 0163F00018
        10728336 PRIMARY LIMIT F
        10734413 BURNER BOX OBSOLETE
        10734504 BURNER BOX TOP OBSOLETE
        10734609 BURNER BOX FRONT
        10735003 IGNITOR F 10735003A
        10735102S BECKETT BURNER F
        10735201 FLAME SENSOR F
        10736102 HIGH VOLTAGE BOX 0161F00012S
        10736201 COVER, HIGH VOLTAGE BOX
        10759617S USERS MANUAL F
        10764320 ROTATING PLATE
        10764601 ROTATING PLATE GASKET
        11034809 BLOWER DECK
        11072204 ORIFICE SHIELD
        11094104 HEAT EXCHANGER ASSY 5B
        11094903 CORNER BRACKET
        11118705 WIRING HARNESS 16-PIN F
        11142203 COLLECTOR BOX/ID GASKET
        11177105 PRESSURE SWITCH F
        11177202 ID BLOWER
        11185804 BLOWER HOUSING ASSY 11185817
        20006603 INSULATION
        20024603S VENTING MANUAL F
        20158901 INTERFACE BOARD
        20159002 WIRING HARNESS F
        20213106 NAMEPLATE S
        20214001 BOARD PLATE
        20218901 COIL-INDUCTOR F 0130M00142
        20242801 FILTER RAIL
        20243502 SIDE INSULATION 20243503
        20272803 BLOWER DOOR
        20272903 ACCESS DOOR
        20273203 BACK PANEL OBSOLETE
        20273309 FLUE COVER
        20273405 BASEPAN
        20273701 SIDE PANEL RH OBSOLETE

      3. Hi Steve,
        I have gathered some more information, and a snapshot of the 3rd technician’s diagnosis and recommendation from yesterday’s invoice:
        Brand Model Serial #
        AMANA GUIV115CX50 9906220939
        Circuit board is dropping out induce draft motor when igniter comes
        on. Will price the component. Unit has single stage Tstat that needs
        to be a two stage thermostat
        Cost of these components will be emailed. Please reply to email to
        get parts ordered

        I have read that a two-stage thermostat is not a necessity, but if I need to replace the thermostat anyway, should I opt for the two-stage model? Also, my father seems to remember the tech counting 4 flashing lights on the circuit board, and from what I can gather in the operating manual, that could be one of four things:
        1. a faulty limit or rollout switch
        2. an open auxiliary limit
        3. improper air flow or distribution
        4. cycling on limit

        After further reading the manual, it looks like a remedy for this situation (since I do get heat, just not sufficiently or consistently) might be to replace the induced draft blower, which looks like what the tech is sort of referencing. Could he be leading me in the right direction with a replacement of the circuit board, in that case?

        Thanks in advance for your advice, again!

    2. Just wanted to thank you for your help. Our furnace was not putting out hot air. I read your advice as to what it might be to my husband. He than watched your video about cleaning the flame sensor. He tried it and now we have a warm house again. THANK YOU THANK YOU THANK YOU.

      1. Hi Karen! Thank you so very much for taking your time to write us back with the great news! Congratulations on repairing your furnace! I am glad to hear that it was an easy fix and we were able to help you out! I hope you and your family have a blessed and happy 2016! Steve

    3. Hello, my heater brand is York, and is like 15 years old .
      When I turn on the heater, the ignite turns red for a few seconds and then turn off.
      I dont see any fire on at all.
      Thank you!
      Alma Garza

      1. Hi! This could be anything from a control board problem to a gas valve problem. Normally the ignitor will glow for 20 to 30 seconds so this makes me feel that it might be a relay on the control board that sends power to the ignitor. I would suggest that you go through our furnace trouble shooting flow chart to determine where the problem is. Here is a link to our furnace troubleshooting flow chart page: Please send me your furnace’s model number if you would like for me to look up parts. I hope you can easily find and fix the problem. Steve

  3. I have a carrier heater on natural gas. It is the original heater in the house from 1977. My pilot light stays lit, lights the burners the blower motor will kick on and blow hot air. It will run for about 10 minutes and all flame goes out even the pilot.

    1. Hi Jeff! Sorry to hear your furnace is not working right. What we would need to find out is… what control or what problem is causing the furnace to cut off prematurely. I would suggest that you test with a volt meter set to “Volts AC” the W and C wires on your furnace’s control board to make sure the thermostat is supplying a constant 24 to 24 volts AC to the control board when the furnace burner and pilot goes off. If the thermostat is cutting the furnace off then you might have a thermostat or heat anticipator problem. We have a basic furnace troubleshooting page with a furnace troubleshooting flow chart on the following page: This could be something as simple as a thermostat problem. This could also be a limit or rollout switch which is causing the furnace to go out. I know a lot of the old Carrier furnaces have the 3 wire pilot burner that if the pilot is not good and blue of if the pilot is dirty it will cut everything off. You might want to clean the 3-wire pilot burner. We sell the 3 wire pilots on the following page: I hope you can easily find and fix the problem. Steve

      1. The pilot flame is bright and blue. The thermostat will kick on and eventually activate the blower motor. The main flames will run about 6 minutes and turn off leaving the pilot light lit with the blower blowing. It will cycle the main burners again and run for about 6 minutes again and this time when it goes out it’ll take the pilot light with it. My thermostat is battery operated by two AAs. Should I change those?

      2. Yes, I would check the batteries. Really about the only way to be sure what is causing the problem is to test the controls with a volt meter when the burners kick out. This will tell you if it is the thermostat or another control causing the problem. Best of luck in finding the problem. Hope you have a blessed day and a Happy New Year! Steve

  4. I have a goodman 2 burner furnace that the main burner will light but the secondary only lights if I run a wire through the jet. I’ve taken the jets off and cleaned them, they are wide open, I’ve blown compressed air through the tube that holds the jets, the burner when both light are burning nice and the crossovers seem clean, the problem is only with the second burner.

    1. Hi Jim! Since you have cleaned the burner orifice and blown the tube out that goes to the orifice jets…the next thing that I would try would be adjust the gas pressure up a little bit on the gas valve. You might not be getting enough gas to light the second burner. If you do not feel comfortable in doing this then I would recommend calling in a professional. I suggest to not turn the gas valve regulator screen more than 1/4 turn at a time. There is a good YouTube video on the following page that discusses this: I explain how to do this in number 6 on the following page: I hope that adjusting the gas pressure fixes your problem. Steve

  5. My furnace main burner ignites, the main burner stays on for 3 to 5 seconds, then shuts right back off. It tries this ignition sequence again, and the same thing happens. After 3 times the furnace goes into lock out. I replaced the flame sensor, but it has the same problem. I called a bad technician who told me that the ignition part needed to be replaced, which I doubt because the flames start. Could this be the problem? Like I said, the flames fires up for a few seconds, so I consider that this part is OK. The technician also told me that the electronic board was bad, and that need it to be replaced.

    Rheem Criterion II Model Number RGPH-12NARJR

    1. Hi Omar! If the furnace continues to have a flame proving problem then I would suggest that you check all wire connections to make sure they are good, tight and not burnt. Please make sure the ground on the furnace is good and tight. Please make sure the flame sensor is sitting in a good blue flame. Yes, If this does not fix the problem then you might need a new control board. Please send me your model number and serial number if you would like for me to look up the part number for the control board. I will need the first two letters of the serial number. Thanks! Steve

      1. Steve,
        I check the voltage across the flame sensor (chassis and the end of the flame sensor). I got 106V with the door switch off, as soon as I press the switch to turn the circuit board, the voltage across the flame sensor drops to .4 V, as soon as I turn on the thermostat, the voltage moves up to 0.6, when the igniter turns on, voltage moves up again to 1.01V, when the flames fires voltages moves up again to 1.4. When the igniter turns off and the gas valve shuts off, the voltages drops again to .4v. Could the circuit board be bad? Why the voltage across the flame sensor drops to 0.4v as soon as I turn on the circuit board?
        Rheem Criterion II Model Number RGPH-12NARJR
        Control board: rheems 62-24084-02

      2. Hi Omar!
        This sounds like you have a short in your wiring somewhere. You should not be getting any voltage across the flame sensor. This could be a short in the control board. The 62-24084-02 control board that you have has been updated to control board 62-24084-82. I do not understand why you are getting voltage to the flame sensor with the door switch off. Sounds like a shorted wire or shorted control problem somewhere. You might want to get a professional to troubleshoot this. Sorry that I can not be much help. Steve

  6. We have replaced the ignitor 3 times within 2mos. Any ideas why it keeps going bad? The first time it was an after market part and thought it just might not be a very good brand. 2nd time we got a better brand so we thought, lasted about a week. 3rd time we have bought a sodium nitride ignitor which we thought would be more durable well after one week it has stopped sparking again and thus, no heat again. We have a Goodman furnace model #GPD075-3. Thank you

    1. We have an article listed on the following page that describes why an ignitor might go out prematurely under the section: “Below are listed some reasons that might cause your ignitor to go out prematurely” Here is a link to our page where we discuss this problem: Our Goodman parts program shows that your furnace uses the B1401018s ignitor. You might consider purchasing the 0230K00001 ignitor kit that we sell on the following page: This kit is a more durable ignitor. You might want to make sure that your ignitor is not staying on after the gas on the furnace is ignited. If the ignitor is staying on more than 15 seconds after the gas ignites then this could cause the ignitor to burn out prematurely. The ignitor timing is controlled by the furnace control board so you might need a new control board. Our parts program shows that your furnace uses the B1809913S control board that we sell on the following page: Please make sure all wire connections, plug connections and ground on your furnace are good and tight. A loose connection can cause high amp draw and burn out electrical parts. Best of luck in finding the problem. Steve

  7. Steve,

    Question I have a carrier furnace number 58pav111-13112

    I have noticed that when it starts up the flames sometimes does not evenly start across the orifices. could it be a dirty flame sensor?

    1. Hi Robert! This sounds like your furnace burners might be dirty or you are not getting enough gas pressure to the burners. I would suggest turning the furnace off then taking the burners out and blow them out with compressed air or use a vac on them. We show how to adjust gas pressure on the following page: About half way down the page. If you do not feel comfortable in doing this I would suggest calling in a professional. The burners should light completely across all burners so the flame sensor can pick up the flame. Your furnace uses the LH680014 flame sensor that we sell on the following page: If the burners are lighting all the way across the flame sensor is not the problem. Please see the following screen shot picture that shows critical parts for your furnace: Best of luck in finding the problem. Merry Christmas! Steve A.

  8. My furnace started having problems out of no where (10 year old unit).

    Furnace flu fan kicks on ignitor glow for a sec at times then shut down. Sometimes it would ignite the pre flame for a couple seconds then shut down. Sometimes it would light completely, all three shoots, then shut down Completely. Led light on gas valve always blinked like nothing wrong.

    Replaced flame sensor and hot ignitor and started up fine…. For a little bit. Shut down early then fire up and work for a bit. Now it is back to the beginning problem. All these times it never tripped any of the reset sensors and one one time did the led flash for multiple start up failure.

    Is it time for a new board? Honeywell

    1. Hi Brian! Your problem sounds like a relay on the control board that provides power to the ignitor is failing. Sometimes when the little relay contacts on the control board become pitted and worn out the furnace will act the way you describe. Sometimes the ignitor will light and glow and other times it will not. Please make sure that your pressure switch is staying closed all the time during the ignition sequence and please check all the wires and connections on the furnace to make sure they are good and tight and not burnt. Sometimes a pressure switch will open and close during ignition especially on a windy day or a loose wire connection will cause the problem you are having. This sounds like a control board issue to me. If you would like for me to look up parts please send me your furnace’s model number. If you have a Bryant Carrier furnace I will need the product number. I hope you can easily find the problem. Steve

  9. I have a Trane / American Standard model #ycc042F1MOBA. I’m having trouble with my furnace lighting and then kicking off after a few seconds. I cleaned my flame sensor and it got better than it started acting up again. One thing I’ve noticed is when the unit shuts down my purge fan stays running. I’m having trouble finding a flame sensor using this model number. The closest sensor number I could find was Sen0233. Any ideas would be appreciated.
    Thank you
    P.S. These are the numbers that were on my sensor “929643P01”, “PSE TR4”, “9233”

    1. Hi! Our Trane parts program shows that your furnace uses flame sensor part number SEN00297 which we sell on the following page: Please see the following screen shot picture that I took from our Trane parts program: Please make sure all your wire connections and ground connections are good and tight. We have the flame sensor in stock. I hope this solves your problem. Steve

  10. Burners light for a few seconds then go out. I cleaned the flame sensor and it worked only a couple times, and problem returned. I replaced the sensor with a new one, it worked then problem has now returned again. Could it be another issue?

    1. Hi Anthony! Please make sure that the ground is good on your furnace and all connections are good and tight. A burner flame that is not good and blue and not touching the flame sensor can cause the flame sensor to not sense a good flame. Please make sure the flame sensor is sitting in a good hot blue flame when the burners come on. Sometimes the problem can be in the control board. Best of luck in finding the problem.

  11. Thanks, this tip on cleaning the flame sensor kept my thanksgiving warm!

    1. Awesome! Glad to hear you fixed your furnace by cleaning the flame sensor! Thanks so much for letting me know our page helped you out! Hope you and your family have a blessed Thanksgiving and Christmas Holiday! Steve

  12. My burners work fine while the cover is off but they go out soon after I put it back on. I can feel it pulling air through when it is cracked. When the cover is on it will burn out then ignite Every minute or so. What could be wrong.

    1. Hi Jesse! This sounds like an air fuel mixture problem. Please check to make sure that your pressure switch is staying closed when the gas burners go off. If you have an obstruction in the vent or a leaking heat exchanger the furnace will act like you are describing. You can test a pressure switch the same way that I show how to test a rollout switch on the following page: The rollout switch testing is a little more than half way down the page. I Googled pressure switch testing and came up with the following: I hope you can easily find the problem. Steve Arnold

    2. I’ve had this very same issue with a Bryant high efficiency unit. It turns out the air intake pipe from the roof was blocked and the unit could draw clean/cold air into the combustion chamber. Remove a wasp’s nest and all was good.

      1. Thanks so much for telling us about the wasp’s nest in the vent pipes blocking the furnace vent. I hope you have a great day! Steve

  13. I have a comfort maker main burner kicks on for about 15 seconds (3 times) then the second one kicks on for about 30 seconds and the both go out. I have replaced the flame sensor, gas valve ( smart valve) ,pressure switch . I don’t know what else to try.

    1. Hi Mr. Ralston! Since that you say one burner kicks on for about 15 seconds and the second burner kicks on for about 30 seconds this tends to make me believe that you do not have enough or you have too much gas pressure coming out of your gas valve. Normally, both burners should light at the same time and burn continuous until the wall thermostat is satisfied. Your furnace gas is probably cutting off because the flame sensor is not sensing the flame on the burners so it tells the control board to cut the furnace off. Adjusting gas pressure can be dangerous. I would suggest leaving this to a professional who has a Water Column gage. Here are some links to some YouTube videos if you feel comfortable in trying yourself: Best of luck in fixing this problem. I hope you have a great day! Steve Arnold

  14. I got a 2yr old Goodman…its goes through the cycle properly….after the blower comes on for maybe 30-40 seconds…the burners goes out…..I change the pressure switch…flame sensor and control board…..and its still cutting out early….I check the flute pipe…and voltage…….still cuts out…..I’m all out of ideas as to what is happening..

    1. Hi Dante! About the only way to find out for sure where the problem is would be to use a volt meter. If you do not have a volt meter it will be a guess as to where the problem is located. I would suggest that you purchase a low cost multi-meter at Home Depot, Radio Shack or other electronics store. When you get the meter I would suggest sitting it on “Volts AC”. Tape the furnace blower door safety switch down so you can get power to the furnace with the blower door open. Turn the thermostat up for heat and test between the thermostat wires W (white) and C Com (usually purple or blue on Goodman). You should get a constant 24 to 28 volts AC between the W and C terminals when the thermostat is calling for heat. If the voltage cuts out when the furnace goes off then you probably have a thermostat problem. Please make sure the batteries are good on your thermostat if your thermostat has batteries. Next, I would check all the safety controls, the pressure switch, limits and rollouts to make sure they are all closed when the furnace flame goes out. I know that on Goodman there is a somewhat hidden limit control that sits on the bottom of the blower housing. Please make sure this limit is checked out and not missed. I have missed seeing it before. If all of these safety controls are closed when the furnace gas goes off then I would check the gas valve. If you are getting 24 volts to the gas valve and it is not opening then this could be a gas valve problem. We have a furnace troubleshooting flow chart on the following page: I hope this will help you find the problem. God Bless you and your family. Steve Arnold

  15. mine does this and has no sensor. its just a spiral ignitor with a hot surface ignitor box. Changed the spiral ignitor and still same problem. Do I change the gas valve or the HSI??

    1. Hi Joe!
      It is very unusual for a furnace to not have a flame sensing device. Please send my your furnace’s model number and I will try to look up the parts for your furnace. You would need to determine what device is causing the gas to cut off prematurely. I have seen safety devices (pressure switches, limits) cut off the gas burner’s prematurely. You would need to test with a volt meter to make sure all your safety devices are staying closed when the furnace cuts off including the thermostat connections between W and C on the control board. You should get a constant 24 to 28 volts between W and C on your control board. The hot surface ignitor should not be the problem. The purpose of the hot surface ignitor should only be to ignite the natural gas at the furnace burners. Since the gas is staying on for a short time I would think that the Gas valve is not the problem. Best of luck in finding and fixing your problem.

      1. Steve – Similar to Joe N, our furnace also does not have a flame sensor. I’ve looked at every spot and cannot locate anything that resembles one. I’ve followed all wires and there aren’t any that lead into a location where a sensor might be hiding.

        I’ve tried checking the web for information on our furnace, but cannot seem to find much info. The furnace we have is… Rheem RGDG-07NAUER.

        I’ve read that not all furnaces have flame sensors. If that is the case, and mine doesn’t, what would be causing the furnace to power off before getting to the temperature set on the thermostat?

        Thanks in advance.

        Mike T

      2. Hi Mike! Please send me the first two letters of your serial number and I will be able to tell you if your furnace has a flame sensor or not. I hope you have a great day!

      3. Steve

        Serial Number begins with CD


      4. Hi Mike! Our Rheem, Ruud parts program shows that your furnace uses flame sensor part number 62-23543-01 that we sell on the following page: If your furnace is cutting off before it reaches temperature on the thermostat I would suggest that you check your limit on the furnace to make sure it is staying closed all the time. If the limit opens it will cut the gas off until the furnace cools down. Also test between terminals W and C (com) and make sure your thermostat is not cutting the furnace off early. Please make sure if your furnace has batteries that the batteries are in good shape. Best of luck in finding the problem. Steve

      5. Steve

        Thank you for your time and assistance.

        I’ve checked the links you provided, and read through 92-23651-01-01 Installation Instructions. I’ve gone through the furnace again, but cannot locate the flame sensor.

        Here is a picture of my furnace…

        Are you able to see it?

      6. I should have caught this earlier, Sorry. Our program shows that your furnace uses the 62-24084-82 control board and if your furnace was built before the 32nd week of 1994 it might not have a flame sensor and the only way to add a flame sensor that I know of is to upgrade to the new board and purchase the flame sensor kit 62-24044-71. You should be able to tell if your furnace was built before F3294 by the serial number on your furnace. I should have asked for the full serial number. Please see the following screen shot from our parts program: We sell the control board on the following page: We sell the flame sensor kit on the following page: If the burners on your furnace are staying on longer than 15 seconds then more than likely the flame sensor is not the problem. If you have a flame sensor problem the furnace burners only stay on from 1 to 10 seconds. Best of luck in finding the problem. Steve

      7. No worries Steve. I truly appreciate the help.

        My full serial number is CD5D302 F4792 0623

        I’m wondering if this unit does not have a flame sensor, perhaps the Rollout Limit Switch is going bad, which I see is #47-22861-01 on your site.

        I’ll keep an eye on this since it doesn’t happen each and every time I run the heater.

        Thanks again for your help. I hope you have a wonderful holiday.


      8. Hi Mike! Yes, according to your serial number your furnace was made the 47th week of 1992 so yes, you would need to purchase the new board and the flame sensor kit to add a flame sensor to your furnace. When the furnace acts up you should be able to test the rollout switch and the limit switch with a volt meter to see if the circuit is opening on the rollout or limit. A pressure switch that opens up can also cause the gas to cut off. I show how to test rollouts with a meter on the following troubleshooting page we have: I hope you have a blessed day and weekend! Steve

  16. thanks for the info and the video it gave me the confidence to have a second look at the problem . sure enough it was the sensor and it was not much debris on it , a cleanup and it was fine

    1. Great! Awesome glad to hear that you were able to fix your furnace problem. Thank you so very much for taking your time to tell us the great news! Hope you have a blessed day! Steve

  17. This is our first blog posts. I will be happy to try and answer any questions you have. Thanks so much for your interest and support in our website! Hope you have a blessed day! Steve

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