Results 1 to 8 of 8
  1. #1
    Join Date
    Dec 2006
    Location
    Salem
    Posts
    47

    Hmm LENNOX G40 gas furnace question.

    I am an apprentice doing installs and I recently installed a Lennox G40 gas furnace with air conditioning at my mothers house. I am trying to figure out how to bump up the fan speed. On the board, there is sort of a dip switch that reads 60 80 120 160. Is that the CFM switch for fan speed or is that the defrost timer for a heat pump? Install manual is not that helpfull. Want to get advise first before I mess with it so I dont fry something on the bored. Any info would be helpfull.
    Last edited by rickwm228; 03-02-2007 at 08:30 PM. Reason: misspelled word.

  2. #2
    Join Date
    Jan 2007
    Posts
    332
    60 80 120 160 is the fan off delay settings after burner shuts down.
    Change speeds at control board by selecting either the black, yellow, blue or red blower wires for speeds. Black for Air Conditioning(cool terminal), and your choice of yellow, blue or red for heat(heat terminal). One wire will be parked(if four speed) and the other will go to circ fan terminal. Two wires will be parked if the circ fan terminal is not on the board.
    Believe none of what you hear and half of what you see.

  3. #3
    Join Date
    Dec 2006
    Location
    Salem
    Posts
    47
    I dont really get what parked means? that mean just capped? so what do i do to just bump it up to more cfm?

  4. #4
    Join Date
    Dec 2006
    Location
    Salem
    Posts
    47
    do i just change the terminals around on the bored? I also installed a honeywell vision pro 8000 and set it to blow the fan 90 seconds after the call for heat ends. Do i do something different with that?

  5. #5
    Join Date
    Jan 2007
    Posts
    332
    Parked will be labeled on the control board for the left over speed wires. It is a terminal that doesn't connect to anything, just a termination for the extra wire. The heat speed is usually set with a blue wire from factory and if it is then you really can't increase it anymore. Leave the black on the cool terminal. Why does it need to be increased?
    Believe none of what you hear and half of what you see.

  6. #6
    Join Date
    Dec 2006
    Location
    Salem
    Posts
    47
    Needs to be increased because she has a fairly large duct system and would like to get more aiflow since ac needs more cfm.

  7. #7
    Join Date
    Jan 2007
    Posts
    332
    I would let the furnace end the blower cycle and not the stat. If you apply for a pro membership then a lot more information can be given to you.
    Really not allowed to give DIY advice in the residential forum. So for now, this is the best I can do. If you have an installation book you might be able to find how to adjust fan.
    Believe none of what you hear and half of what you see.

  8. #8
    Join Date
    Jan 2007
    Posts
    332
    If you turn AC on at stat the blower will be running at full CFM and if it still isn't enough CFM then the furnace may be undersized for the duct and house. The black wire is the highest speed available for the blower rpm.
    Believe none of what you hear and half of what you see.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event