Home Repair Forum
Go Back   Home Repair Forum > Indoor Home Repair > HVAC
Register Chat FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Display Modes
  #1 (permalink)  
Old 10-15-2003, 07:53 PM
New Member
 
Join Date: Oct 2003
Location: .
Posts: 3
vlink55
Lennox G12

Hi all,

I'm new and stumble upon this great forum. Hopefully I'll get my heater back on w/ the help from all of you

Well I have a Lennox G12 Gas furnace, 24+ yrs. , The pilot lights up fine, I can see the gas flame, but there's no HEAT. All it blows is cold air. I dont have AC, this is just a gas furnace.
I changed the Thermocouple and nothing. Still no heat All it kicks out is cooooldddd air. Any ideas as to what is wrong? Oh yeah I can't determine where the blower is or what it is. I have some pics that I've taken, maybe somebody can help me on this.

thanks alot
vlink55
Reply With Quote
  #2 (permalink)  
Old 10-16-2003, 01:06 PM
Troy's Avatar
Moderator
 
Join Date: Jul 2002
Location: USA.
Posts: 523
Troy is an unknown quantity at this point
Welcome to the forum!

Here are some pictures that might help someone answer:







Reply With Quote
  #3 (permalink)  
Old 10-16-2003, 04:53 PM
Handyman
 
Join Date: Jul 2003
Location: Milford, OH, USA.
Posts: 120
16x80 is an unknown quantity at this point
vlink55

You could have a couple problems.

You have already ruled out the thermal couple, It is possible that you are getting less than 24v to the gas valve which would allow it to keep the pilot light lit but not enough to open the gas valve!

You could also have a bad main high limit (located on the heat exchanger area with two wires going to it) (one of them is the red one on top of the gas valve) This limit should be normally closed (reading continuity) with no wires hooked to it!

Question is the pilot light getting bigger when you make a call for heat or does it stay the same size regardless?

16x80

Reply With Quote
  #4 (permalink)  
Old 10-16-2003, 11:22 PM
New Member
 
Join Date: Oct 2003
Location: .
Posts: 3
vlink55
16x80

Do you mean the red and yellow wires running to the block shown in picture #1?

Now w/ the "bad main high limit", Is there a way to repair/replace just that? and where is this? I'm sorry for asking too much- I just want the heat back and running.

The pilot light appears to stay the same. I could hear the fan spining but no heat.

Reply With Quote
  #5 (permalink)  
Old 10-17-2003, 03:52 AM
Handyman
 
Join Date: Jul 2003
Location: Milford, OH, USA.
Posts: 120
16x80 is an unknown quantity at this point
Get me a picture of the wiring diagram shown in pic 4, I will be able to help you more with the eletrical road map.

16x80
Reply With Quote
  #6 (permalink)  
Old 10-23-2003, 10:01 PM
New Member
 
Join Date: Oct 2003
Location: .
Posts: 3
vlink55
Hey you guys...

So no one can help me out here w/ the Lennox G12? I am clueless as to what is wrong w/ it. No heat and winter is near.
Reply With Quote
  #7 (permalink)  
Old 10-25-2003, 09:43 AM
New Member
 
Join Date: Oct 2003
Location: Fair Haven, MI.
Posts: 17
a46geo
The gas valve is not opening to allow for the main burner(s) to ignite.
Thermostat, low voltage wiring, transformer, and the gas valve are all common problems that result in what you discribe.

A less common but possible problem could be a gas regulator or the gas pressure itself.

There isn't room here to explain all of the hows & whys, but before you start trial and error replacement, it might just be cheaper to call in a expert.

An expert can also make sure that the thing is operating safe. Carbon monxide leaks can and do occure with age.

At 24 years of age, I wouldn't spend a whole lot of money on it. Ask the utility company to do a return on inverstment analysis for you. If a new furnace will substantually cut your heating bill, that may indeed be your best choice.[?]
Reply With Quote
  #8 (permalink)  
Old 10-26-2003, 06:20 PM
Troy's Avatar
Moderator
 
Join Date: Jul 2002
Location: USA.
Posts: 523
Troy is an unknown quantity at this point
Here are some more pics:







Reply With Quote
  #9 (permalink)  
Old 12-08-2003, 12:02 PM
New Member
 
Join Date: Dec 2003
Location: .
Posts: 1
rkelder
Hope it's OK to jump on this thread as my problem is about the same.

I've got the same system, pilot light kicks up when the thermostat calls to it, ignitor clicks away and then resets. But not all the time, system works in the morning every day, but hit and miss in the evenings. Did first step and put a new thermostat in, what should be my second step?

Thanks in advance

Ray

Reply With Quote
  #10 (permalink)  
Old 12-30-2003, 09:55 PM
New Member
 
Join Date: Dec 2003
Location: tor, Canada.
Posts: 1
Muggle
I know its a little bit off topic, but it appears that you have no filter in that unit. In the long run, that can lead to damage. That frame in the blower compartment should have filter media in it.
Reply With Quote
Reply



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
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

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

» Forum Navigation
     > Forum News
     > Illustrations
     > You Gotta Laugh!
     > Catch All
     > Plumbing
     > Electrical
     > Flooring
     > Wall Coverings
     > HVAC
     > Stenciling
     > Appliances
     > Audio & Video
     > Projects
     > Faux Painting
     > Painting
     > Gardening
     > Decks & Fences
     > Outdoor Projects
     > Garage Doors
» Links

» Search

Home Repair Forum
Google   
» Online Users: 30
1 members and 29 guests
Psycho0124
Most users ever online was 388, 07-01-2007 at 01:54 AM.
Powered by vBadvanced CMPS v2.2.0

All times are GMT -5. The time now is 01:13 AM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2008, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.1.0