Lennox Gas Furnace - HVAC - DIY Chatroom Home Improvement Forum


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

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

Reply
 
Thread Tools Display Modes
Old 01-17-2012, 11:39 PM   #1
Newbie
 
Join Date: Jan 2012
Posts: 1
Rewards Points: 10
Default

Lennox Gas furnace


My Lennox gas furnace tries to come on but burners won't stay lit?

Advertisement

THeavrin is offline   Reply With Quote
Old 01-17-2012, 11:49 PM   #2
Member
 
Houston204's Avatar
 
Join Date: Oct 2009
Location: Texas
Posts: 594
Rewards Points: 514
Default

Lennox Gas furnace


Clean the flame sensor.
It will have a single wire connected to it.
Avoid the ignitor, it is easy to break and will also be located in front of the burners.


Advertisement

Houston204 is offline   Reply With Quote
Old 01-18-2012, 12:01 AM   #3
how
Member
 
Join Date: Feb 2011
Location: Vancouver BC
Posts: 1,545
Rewards Points: 606
Default

Lennox Gas furnace


Age and model would help.

Look on the furnace through a grill or inspection port for a flashing led light. That flashing light sequence will match a legend on the door that will point to what the furnace problem is. Tell us what you find.

Last edited by how; 01-18-2012 at 12:13 AM.
how is offline   Reply With Quote
Old 01-18-2012, 12:10 AM   #4
I'm Your Huckleberry
 
Join Date: Mar 2011
Posts: 5,884
Rewards Points: 2,220
Default

Lennox Gas furnace


Quote:
Originally Posted by Houston204 View Post
Clean the flame sensor.
It will have a single wire connected to it.
Avoid the ignitor, it is easy to break and will also be located in front of the burners.


this. happens on all (older) gas furnaces from time to time. that little rod is inolved with flame rectification, dc voltage to ground through the flame. let's the furnace know that there is a flame so the call for heat (gas valve) remains on. once sut and corrosion builds up on the flame sensor it interferes with the sensing of the electrical signal the board needs to keep the call for heat on. It's telling the control board there is no flame so to cut the gas off.

anyways, hvac flame senser 101 over and out. easy monkeys. clean it and you will have heat. GoOd lUck.
__________________
Thanks.
Doc Holliday is offline   Reply With Quote
Old 01-18-2012, 08:16 AM   #5
Member
 
Houston204's Avatar
 
Join Date: Oct 2009
Location: Texas
Posts: 594
Rewards Points: 514
Default

Lennox Gas furnace


Modern furnaces still use flame rectification.
Since the flame sensor requires a good ground, it is also a good idea to remove power and wire brush the ground connection entering the furnace and the ground connection on the burner area.

I always get a lower microamp DC reading with Lennox furnaces than other brands. I get 5uAdc with Carrier using OEM boards and 2uAdc with Lennox.
.5uAdc is all that is required with the models I usually service.

I have seen ICM replacement boards for Carrier ask for more and get less.

Last edited by Houston204; 01-18-2012 at 08:26 AM.
Houston204 is offline   Reply With Quote
Old 01-18-2012, 09:40 AM   #6
I'm Your Huckleberry
 
Join Date: Mar 2011
Posts: 5,884
Rewards Points: 2,220
Default

Lennox Gas furnace


I know. What I meant is with older furnaces that have older flames sensors the cleaniing is not an uncommon thing. I'm not going to need to clean a brand new flame sensor in a brand new furnace in other words.

Advertisement

__________________
Thanks.
Doc Holliday is offline   Reply With Quote
Reply


Thread Tools
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
Possible Lennox Furnace ignitor problem Paulg1 HVAC 4 11-26-2010 05:38 PM
Lennox Furnace Model #: 90UGFA3-75-6 GauravJ HVAC 3 10-30-2010 09:24 PM
Lennox Furnace Model #: 90UGFA3-75-6 GauravJ Electrical 0 10-29-2010 07:52 PM
Lennox ghr26 furnace problems wayfis HVAC 8 01-05-2010 06:51 PM
Lennox G11Q3E-110V-6 gas furnace neato5oh HVAC 1 10-07-2006 07:43 PM




Top of Page | View New Posts