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what can happen when a 120v igniter is installed where an 80v igniter should be?

I just bought a house and had the furnace serviced and inspected. The HVAC tech said that someone had replaced the igniter with the wrong one. That they put a 120v igniter in where an 80v igniter should be. He explained that is why sometimes the furnace would not kick on when the thermostat called for heat and that when it did kick on after trying several times it made a noise because of pressure build up. They did not have the parts available so now I am waiting and I am worrying about the furnace. What can happen when a 120v igniter is installed where an 80v igniter should be? Can the pressure build up get so bad that the furnace blows up? I am concerned and want to find out more.
Any information on what could happen would be greatly appreciated. Thank you!

Comments

  • STEVEusaPASTEVEusaPA Posts: 3,341Member
    edited February 2018
    What make/model number of the furnace? Gas, I assume?
    Let's make sure we're talking about the right part and get the right nomenclature before you worry.
    Are you sure it's not a contactor he mentioned?
    I assume it's not running.
    I don't know about pressure build up in a furnace.
    Post some pictures if you can, and provide some more detail.
    steve
  • HomerJSmithHomerJSmith Posts: 617Member
    edited February 2018
    If the ignitor doesn't get hot enough to lite the gas, the furnace's induced draft motor will do a post purge before a re-light attempt is made. No company would allow a re-light with the combustion chamber filled with gas. However, the 120 V ignitor might be tricking the control board. There is a flame sense that allows the gas valve to stay fully open.

    Is that a Trane, American Standard or Ameristar furnace? They are manufactured by Trane.
  • unclejohnunclejohn Posts: 1,420Member
    This here is America, we go 110v & 220v for residences.
  • HomerJSmithHomerJSmith Posts: 617Member
    Actual AC voltages can vary between 110 V to 125V with the corresponding 220 V. My household voltage is 122 V.
  • JUGHNEJUGHNE Posts: 6,051Member
    The term "nominal voltage" is the correct term.....120/240 volts is the recognized nominal voltage for most of this country.
    Measurement would vary by many factors.
    "2 X 4" is also a nominal number, but go measure one.

    So are there HSI's that run on 80 volts?
    I have only seen 120 or (what I assume) the 24 volt ones on HW Smartvalves....though never had the need to check for 24 volts.
  • olvchelleolvchelle Posts: 2Member
    edited February 2018

    If the ignitor doesn't get hot enough to lite the gas, the furnace's induced draft motor will do a post purge before a re-light attempt is made. No company would allow a re-light with the combustion chamber filled with gas. However, the 120 V ignitor might be tricking the control board. There is a flame sense that allows the gas valve to stay fully open.

    Is that a Trane, American Standard or Ameristar furnace? They are manufactured by Trane.

    HomerJSmith,
    It is an American Standard. What you said seems similar to what I was told during the service call.
    The igniter that is in there now is not the original. It looks like it was replaced just before I bought the house; the old igniter was laying on top of the furnace.

    STEVEusaPA
    I will need to see if I can find the model number of the furnace.
    It is Gas.
    The piece was not a contactor, he said igniter. The American Standard Mnemonic part number is ING0017 (from the owners manual) it is also 768A-15, which is apparently no longer available and 768A-815 is what I am told is the OEM replacement number now.
    The furnace is running. There are many times when it tries to kick-on but doesn't, then tries again and again then finally kicks-on, usually with a noise that, the first time I heard it I thought a chuck of ice had fallen off my roof.

    I will see what I can do about pictures, although hopefully the part number will help you know what it is I am talking about.
    You are correct; I don't really know my furnace nomenclature...yet.
  • JUGHNEJUGHNE Posts: 6,051Member
    A picture of the igniter and the number on it would be good.
  • Matt_67Matt_67 Posts: 173Member
    Your tech is right - the control board on the furnaces that use those igniters reduces the voltage to the igniter. I believe the board went through a routine where it would step down the voltage until the furnace wouldn't light to determine what voltage to send to the igniter - the goal being to extend igniter life. It should have the correct igniter installed.
  • JUGHNEJUGHNE Posts: 6,051Member
    So that is not an "old school" furnace HSI.
    I have installed those with the "HSI ignitor saver system" as you described. But have never had to replace a HSI for those units.
    So there must be a method to the madness of doing it that way as some of these units are several years old and still lighting.
    Thank you.
  • ch4manch4man Posts: 146Member
    listen to Matt, in addition to Trane, Lennox has 80 volt silicone nitride HSI's.

    a big issue is after an update kit has been installed that changes the 80 volt hsi and board to a 120 volt system. now after that if an ignitor is needed and ordered with the model/serial the tech may end up with the wrong hsi as the model/serial doesnt know there has been an update!

    such fun
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