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  1. #14
    Join Date
    Dec 2004
    Posts
    441
    If all else fails we can alway trim a wire and replace the HSI on a G20! I learned something new today!

  2. #15
    Join Date
    Jun 2004
    Location
    Orange County California
    Posts
    63
    Pipedope -
    quote:
    "The lennox g20 is spark ignition!!!!!!!!"
    Yea, you are absolutely correct. I was so focused on doubleshot's thread that I totally missed that.
    Thanks!


    [Edited by rcrainman on 03-01-2005 at 07:25 AM]

  3. #16
    Join Date
    Oct 2003
    Location
    west chester pa
    Posts
    343
    no Sweat!!

  4. #17
    yea, i noticed it was a spark ignition, hence the clicking, and hence why trimming the wire to make a better connection for electricity helped.

    The pilot now lights every time heat is asked for, where before it acted like it didn't have enough electricity to send a spark and no ignition occured...

    as for it shutting off sometimes after a few minutes before desired temp is recieved, the burner shuts off then the blower shuts off about a minute after. This sounds like the flame sensor, I just haven't had time to take it apart.

    I'm not an hvac guy, actually a computer engineer, however there are certain things that are just common since...

  5. #18
    Join Date
    Oct 2003
    Location
    west chester pa
    Posts
    343
    i Would suggest if problem continues have a hvac guy change control.

  6. #19
    Join Date
    Mar 2005
    Location
    burlington county n.j.
    Posts
    9,743
    if it was my house i would install 53l90 as stated by others just because johnson blue box was a true P O S
    i have probably replaced 100 of these in last 5yrs.
    replacement is honeywell. have not had one fail yet.
    ted

  7. #20
    Join Date
    May 2005
    Posts
    1
    doubleshot:

    I think the furnace is designed so that the blower fan remains on for a while after the burner has stopped because there is still hot/warm air in the ventilation system. It operates a little while longer to push the rest of the warm air into the house.

  8. #21
    Join Date
    Dec 2004
    Posts
    76

    Lennox G20 with spark ignition

    Just worked on one with the same exact problem. After cleaning the fame sensor. Sometimes it would spark up and fire and sometimes it would spark up, pilot would lite and drop out. Check the pilot flame and make sure that the flame is strong and hitting the flame sensor. I ended up removing the pilot assembly...took it apart washed it then reassembled....it worked perfect.

  9. #22
    Join Date
    Mar 2005
    Location
    Suppy NC
    Posts
    4,513
    the G20 also has a damper door spring witch is a saftey keeping the burners from coming on if the damper does not open. after time this spring looses its tension and needs to be replace noraly ever 4 year. if this happens it can cause the unit to shut off mid cycle
    order the proper control and the spring and fix it correcty

  10. #23
    Join Date
    May 2004
    Location
    Canada
    Posts
    317

    Lightbulb


    The g20 is the whisperheat which has direct spark ignition and at one time standing pilot.I would have the heat exchanger checked on that my friend because ignition is the least of your problems.........DURACURVE>>>>>>>>snap CRACK pop.Have a nice day

  11. #24
    Join Date
    Sep 2001
    Location
    Vancouver Canada
    Posts
    996
    Make sure your pilot burner is clean and pilot flame is a nice blue, not yellow. Lennox is famous for dirty pilots, look like a big candle burning in there. As for not reaching temperature, I don't believe it will be the flame sensor, check the anticipator setting on the Tstat. As mentioned also check that the tstat is mounted level. Check to make sure that the unit is not shutting down on high limit. Filters clean? Return air grills big enough and not blocked? Registers all open? A lot of jobs I see people close half the registers to force more heat upstairs or downstairs, problem is it quite often overheats the furnace due to lack of air across the heatexchanger. Try turning the tstat up right after the burner shuts down and if the burner lights again right away you will know that the low voltage circuit is complete (no open limits.)

  12. #25
    Join Date
    Jul 2002
    Location
    St Paul, Minnesota
    Posts
    3,468
    Originally posted by doubleshot
    yea, i noticed it was a spark ignition, hence the clicking, and hence why trimming the wire to make a better connection for electricity helped.

    The pilot now lights every time heat is asked for, where before it acted like it didn't have enough electricity to send a spark and no ignition occured...

    I'm not an hvac guy, actually a computer engineer, however there are certain things that are just common since...
    (Time to look up and understand flame rectification. It is very important to know this for the Whisperheats.)


    Lot of blue Johnson ignition controls have been changed out, some too early when the problem is actually a too low signal thru the pilot assembly. (In which case the I.C. is doing it's job, but the ignition control would have failed eventually. Cleaning the underside of the pilot hood and insuring the pilot oriface is clean helps increase the voltage signal but if you go to all the trouble of removing it, you are better off replacing it, cause it will carbon up in a year or so and you are back to intermittant operation.


  13. #26
    Join Date
    Jun 2005
    Posts
    285
    Forget the crap Lennox over priced part. Just replace it with a standard Honeywell universal spark ignition control which is basically all the Lennox replacement is anyway.

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