Lennox WhisperHeat G20 burners only working part of the time


  #1  
Old 02-17-14, 03:04 AM
S
Member
Thread Starter
Join Date: Feb 2014
Posts: 14
Upvotes: 0
Received 0 Upvotes on 0 Posts
Lennox WhisperHeat G20 burners only working part of the time

We have a Lennox WhisperHeat G20 Q2E50-4 furnace from approximately 1994, when the house was built. For a couple of days, we've noticed the furnace will kick on and run for about 2 minutes, then shut off, then five minutes later do it again. When it kicks on, we can see the pilot light is on but not the burners, and the air that comes out isn't warm. However, after anywhere from two to five hours of this, the furnace will work properly and the burners will come on.

So far we've checked the ducts and flue for blockages, none found. The furnace filter is new (but we only use the thinnish "rock catcher" type which are thin enough that I can't imagine they obstruct air flow at all) and we used the vac to suck up dust inside the furnace in case there was a blockage, but it didn't change anything. The damper door works fine, the flame on the pilot is blue. The furnace itself doesn't get hot during these short runs, so I don't think it's shutting down from overheating. We reset the flame rollout switch a couple times, but no luck. Every time the furnace would click on, the pilot light would go, but the burners just wouldn't catch and it would shut down.

About an hour after we stopped troubleshooting the few things we knew how to do (and after at least six two-minute runs from the furnace) it turned on and this time worked, hot air coming from the vents, burners all lit with nice blue flame. Coming on after hours of not working has happened twice since Saturday night.

We're thinking it might be a gas valve issue. Hopefully not a control panel issue; we replaced that back in 2008 and it's just out of warranty as of last November.

Any thoughts? The service tech can't get out here until Tuesday afternoon, and though it's not supposed to get that cold (~35F at night) we'd like to try to get this fixed a little sooner. Thanks!
 
  #2  
Old 02-17-14, 10:36 PM
S
Member
Thread Starter
Join Date: Feb 2014
Posts: 14
Upvotes: 0
Received 0 Upvotes on 0 Posts
Looks like the repair place can't get out here until Wednesday morning - any thoughts you have would be most welcome! The furnace will work for hours but then goes out again, and takes all night to "fix itself," so it gets kind of chilly in here. Thanks!
 
  #3  
Old 02-18-14, 07:14 PM
M
Member
Join Date: Dec 2004
Location: San Jose,Ca
Posts: 1,277
Upvotes: 0
Received 3 Upvotes on 3 Posts
Does your furnace have a Johnson ignition module, blue and grey in color? They were a problem after a few years and would act as you described.
 
  #4  
Old 02-19-14, 09:53 AM
S
Member
Thread Starter
Join Date: Feb 2014
Posts: 14
Upvotes: 0
Received 0 Upvotes on 0 Posts
I completely forgot to ask which module it was -- sorry! But the repair place came out this morning and verified it IS the ignition control panel.

Johnson is the original brand that this came with, right? If so, then the one we had wasn't the Johnson module, the original ignition went out in 2008. We had it replaced, but I don't recall what the brand was (and I can't see it at a glance when looking in there).

This guy told us the type of ignition module the furnace uses isn't made anymore -- I assume he means the Johnson -- but he went on to say any replacement ignition modules will be "temporary" and the entire furnace should be replaced. I'm not convinced in the least, not after what I've read online. Whatever he says, we're not getting a new furnace.
 
  #5  
Old 02-19-14, 10:27 AM
M
Member
Join Date: Dec 2004
Location: San Jose,Ca
Posts: 1,277
Upvotes: 0
Received 3 Upvotes on 3 Posts
Thanks for the reply, it is nice to hear the results. As you probably guessed it can be difficult troubleshooting remotely.
 
  #6  
Old 02-21-14, 08:25 AM
S
Member
Thread Starter
Join Date: Feb 2014
Posts: 14
Upvotes: 0
Received 0 Upvotes on 0 Posts
We just had the ignition control panel replaced. The one they installed in Nov 2008 was a Honeywell, which was working off and on -- it hadn't completely gone bad and had just run for 26 hours without conking out, so we held on to it as an emergency backup. This new replacement is also a Honeywell, this time with a diagnostic light on it, and a sheet of codes to check if the furnace ever stops working. (Blinks twice means aliens are approaching, or something, lol.) This repair guy said our furnace was really solid, the quietest one he's ever worked on, and his experience with the Honeywell ignition control panel he just installed is that they have a really long lifespan.

Just wanted to post a final update in case anyone does a 'net search with the same problem. Thanks all!
 
  #7  
Old 02-21-14, 09:18 PM
user 10's Avatar
Member
Join Date: Mar 2004
Location: NA
Posts: 1,821
Received 56 Upvotes on 49 Posts
The lennox G20 is known for bad heat exchangers which split open right where they curve. It's not a solid or efficient furnace, and if you have any more problems, don't put more money into it -> just replace it.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: