Page 1 of 2 12 LastLast
Results 1 to 13 of 14
  1. #1
    Join Date
    Oct 2005
    Posts
    12
    I have a Lennox G20Q2E that appeared dead. The 2 amp glass fuse was blown. I replaced it and the fuse remained good with no call for heat. Stat called for heat and the electric damper started to open then the fuse blew and the wall stat started to smell of smoke. I dont see many Lennox products and have seen none with a motorized damper. Is the relay board causing the fuse to blow or is one of the devices hooked to it loading it down? Why did the stat heat up so fast? Why does this natural draft unit have a motorized damper? thanks for any help!!!

  2. #2
    Join Date
    Mar 2004
    Location
    SE Michigan
    Posts
    17,995
    You have a short somewhere on the 24vac side.
    Behind the ostensible government sits enthroned an invisible government owing no allegiance and acknowledging no responsibility to the people.

    Theodore Roosevelt

  3. #3
    Join Date
    Sep 2002
    Location
    I don't know
    Posts
    2,903
    Lennox used a motorized damper to get away with selling a conventional furnace as a mid efficiency unit. (rated efficiency - 78% AFUE)

  4. #4
    Join Date
    Mar 2005
    Location
    burlington county n.j.
    Posts
    9,748
    better call for service before anything else lets the smoke out

  5. #5
    Join Date
    Nov 2001
    Location
    east kansas
    Posts
    8,032
    seen a lot of theese units with bad heat exchangers. Could still be under warranty for the heat exchanger only.
    Beware of advice given by some guy on the Internet.

  6. #6
    Join Date
    Mar 2005
    Location
    burlington county n.j.
    Posts
    9,748
    Originally posted by lynn rodenmayer
    seen a lot of theese units with bad heat exchangers. Could still be under warranty for the heat exchanger only.

    never saw bad heat exchanger on small one like this. never saw bad heat exchanger blow fuse either.LOL

  7. #7
    Join Date
    Oct 2005
    Posts
    12
    thanks for you input. I have isolated the board but the fuse still blows with a flash of a dead short even tho I checked every wire in the furnace and disconnected all the stat wires. The fuse protects the 24 volt supply but only blows when the R and W is jumpered. The relays switch the 120 volt devices so they should not be causing any trouble. Can the board fail internally in a way that it only pops the fuse when R W make? Does the relay board have a history of this on the lennox?

  8. #8
    Join Date
    Mar 2005
    Location
    Suppy NC
    Posts
    4,513
    it could be the board. i tend to think there is a short to ground on w

  9. #9
    Join Date
    Oct 2005
    Posts
    68
    It most likely is a short on the 24V side. Some of those are difficult to find and can take quite a bit of time. You might also check to see if the damper is getting stuck and the motor is pulling high amperage. That probably isn't the case but I would still check it.

  10. #10
    Join Date
    Oct 2005
    Posts
    12
    the damper motor is 120 volt switched from a relay so it shouldnt load the 24 volt supply. The fuse pops so fast that its got to be a virtually dead short. But there are no dead or low ohms readings anywhere. thanks for the feedback. May have to get the board.

  11. #11
    Join Date
    Nov 2001
    Location
    east kansas
    Posts
    8,032
    Originally posted by t527ed
    Originally posted by lynn rodenmayer
    seen a lot of theese units with bad heat exchangers. Could still be under warranty for the heat exchanger only.

    never saw bad heat exchanger on small one like this. never saw bad heat exchanger blow fuse either.LOL
    First thing I'd do on this service call is inspect the heat exchanger. Just because you haven't found many cracks doesn't mean they weren't there. Read into that anything you want.

    Then if the heat exchanger was good, I'd look for the short.

    First things first.
    Beware of advice given by some guy on the Internet.

  12. #12
    Join Date
    Oct 2005
    Posts
    12
    thanks for the help. unit has been scrapped due to age and low efficiency. never did find the short, removed all wires in and out of board, must have been the board

  13. #13
    Join Date
    Mar 2005
    Location
    burlington county n.j.
    Posts
    9,748
    Originally posted by vapourman
    thanks for the help. unit has been scrapped due to age and low efficiency. never did find the short, removed all wires in and out of board, must have been the board

    what replaced it??

Page 1 of 2 12 LastLast

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