Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > HVAC

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 01-14-2013, 02:53 PM   #1
Newbie
 
Join Date: Jan 2013
Posts: 7
Share |
Default

lennox furnace wont stay lit


I have a model lf24 that runs for about 2-3 min then shuts down and starts over will not stay lit though the fan blows constantly.I have changed the heat sensor the flame sensor the board the gas valve. The first time it comes on it runs for about 2.5min then as it warms up it gets down to running only about 30 sec any ideas?

adamsqh is offline   Reply With Quote
Old 01-14-2013, 03:18 PM   #2
Member
 
Join Date: Sep 2011
Location: western Ny
Posts: 1,243
Default

lennox furnace wont stay lit


Well, since you have changed out almost everything accept possibly the high limit or the filter I would start there. Sounds like the furnace is shutting down on overtemp. How is the airflow in and out of the furnace?

danpik is online now   Reply With Quote
Old 01-14-2013, 07:25 PM   #3
Member
 
Join Date: Oct 2009
Location: Nebraska
Posts: 2,362
Default

lennox furnace wont stay lit


About all you have left is inducer and pressure switch.
Marty S. is offline   Reply With Quote
Old 01-15-2013, 05:33 AM   #4
Member
 
Join Date: Jan 2013
Location: Atlanta
Posts: 122
Default

lennox furnace wont stay lit


Quote:
Originally Posted by adamsqh View Post
I have a model lf24 that runs for about 2-3 min then shuts down and starts over will not stay lit though the fan blows constantly.I have changed the heat sensor the flame sensor the board the gas valve. The first time it comes on it runs for about 2.5min then as it warms up it gets down to running only about 30 sec any ideas?
Sounds like a tired gas valve to me. Throw a voltmeter on the GV leads and see what comes first; loss of fire or loss of voltage. If voltage stays then your GV is at fault. Voltage goes first, then maybe overheat sensor?
64pvolvo1800 is offline   Reply With Quote
Old 01-15-2013, 10:02 AM   #5
Newbie
 
Join Date: Jan 2013
Posts: 7
Default

lennox furnace wont stay lit


Ok I changed the high limit and the pressure switch and got good air flow through he vent and still wont stay on and it wont give me a blinking code it blinks everything normal. Im getting ready to swap the whole thing out.
adamsqh is offline   Reply With Quote
Old 01-15-2013, 10:05 AM   #6
Member
 
Join Date: Jan 2013
Location: Atlanta
Posts: 122
Default

lennox furnace wont stay lit


Gas valve test.?
64pvolvo1800 is offline   Reply With Quote
Old 01-15-2013, 10:07 AM   #7
Newbie
 
Join Date: Jan 2013
Posts: 7
Default

lennox furnace wont stay lit


didnt check voltage on gv just changed it.
adamsqh is offline   Reply With Quote
Old 01-15-2013, 10:12 AM   #8
how
Member
 
Join Date: Feb 2011
Location: Vancouver BC
Posts: 1,489
Default

lennox furnace wont stay lit


If your gas valve is shutting off without a code on the board either the
thermostat circuit is being interupted (pigtail R & W on the furnace) or the board is bad.
how is offline   Reply With Quote
Old 01-15-2013, 10:18 AM   #9
Newbie
 
Join Date: Jan 2013
Posts: 7
Default

lennox furnace wont stay lit


Ok I changed the board already but have not changed the thermostat I wired it constant so it should have ran nonstop and it still shut down.
adamsqh is offline   Reply With Quote
Old 01-15-2013, 10:45 AM   #10
how
Member
 
Join Date: Feb 2011
Location: Vancouver BC
Posts: 1,489
Default

lennox furnace wont stay lit


Jumpering R & W where the stat wires connect to the furnace eliminates the chance its a partial break in the thermostat line. Make sure to disconnect the stat wires before you jump R to W.
A faulty thermostat circuit won't get picked up by the board diagnostics. Beyond that, the board should be giving you a fault led reading.
how is offline   Reply With Quote
Old 01-15-2013, 10:58 AM   #11
Newbie
 
Join Date: Jan 2013
Posts: 7
Default

lennox furnace wont stay lit


ok I just replaced the stat and still no bueno I am at a loss I think I am going to have to change the unit out with another one that I have if no other sugestions.
adamsqh is offline   Reply With Quote
Old 01-15-2013, 11:00 AM   #12
Newbie
 
Join Date: Jan 2013
Posts: 7
Default

lennox furnace wont stay lit


could it be that im not getting enough gas pressure?
adamsqh is offline   Reply With Quote
Old 01-15-2013, 03:54 PM   #13
how
Member
 
Join Date: Feb 2011
Location: Vancouver BC
Posts: 1,489
Default

lennox furnace wont stay lit


Pigtail the R & W stat wire connections inside the furnace, Not at the thermostat. Turn off furnace power/ detach stat wires from R & W inside the furnace/ connect a wire between the R & W/ put furnace doors back in place/ turn power back on.
If it still shuts itself off...Thermostat circuit is OK but Board is suspect!
If it runs continuously...thermostat wiring or thermostat is the problem.
how is offline   Reply With Quote
Old 01-15-2013, 04:21 PM   #14
Newbie
 
Join Date: Jan 2013
Posts: 7
Default

lennox furnace wont stay lit


Thanks for all the advise i found out the inducer vent that goes to the pressure switch was plugged. Thanks
adamsqh is offline   Reply With Quote
Old 01-15-2013, 05:39 PM   #15
how
Member
 
Join Date: Feb 2011
Location: Vancouver BC
Posts: 1,489
Default

lennox furnace wont stay lit


Hey adamsqh
I hope all is now well.
Anyone have an idea why the board diagnostic led didn't give a code for a pressure switch shut down?


Last edited by how; 01-15-2013 at 05:42 PM.
how is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Smoke and Vent on a New Lennox Furnace Handymannabee HVAC 3 04-13-2011 03:46 PM
Lennox furnace misbehaving gbwillner HVAC 15 01-24-2011 02:02 PM
Lennox Elite Series Furnace Will not Light xchvyragtopx HVAC 2 01-10-2011 07:36 PM
Lennox Elite Series Furnace Problem steges HVAC 7 11-06-2010 02:49 PM
Olsen furnace won't stay running DaleB HVAC 1 10-16-2010 09:22 PM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.