Miller Nordyne Furnace - Induced Draft Blower thermal cutoff


  #1  
Old 12-16-10, 01:16 PM
J
Member
Thread Starter
Join Date: Dec 2010
Location: USA
Posts: 4
Upvotes: 0
Received 0 Upvotes on 0 Posts
Miller Nordyne Furnace - Induced Draft Blower thermal cutoff

Hi, I have a Miller Nordyne furnace model G5RC100C-16. The thermal cutoff on the induced draft blower keeps on tripping. I thought at first it was the cutoff itself as it didn't feel like it was resetting (no definative click) but it still does it after i replaced the cutoff. Could it be that the blower itself is faulty? its a Magnetek model JE1C003NS. Or are there likely other causes?
 
  #2  
Old 12-16-10, 01:25 PM
lawrosa's Avatar
Super Moderator
Join Date: Dec 2010
Location: Galivants Ferry SC USA
Posts: 15,993
Received 85 Upvotes on 77 Posts
Is the blower working?

Mike NJ
 
  #3  
Old 12-16-10, 01:56 PM
SeattlePioneer's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Jul 2007
Location: Seattle, Wa
Posts: 4,469
Upvotes: 0
Received 1 Upvote on 1 Post
The inducer motor is shutting off on a thermal limit --- is that right? What is it you replaced? Most motor thermal limits are an integral part of the motor and can't be replaced.

Unfortunately, most of what you did and found isn't very clear from what you wrote.
 
  #4  
Old 12-16-10, 01:56 PM
J
Member
Thread Starter
Join Date: Dec 2010
Location: USA
Posts: 4
Upvotes: 0
Received 0 Upvotes on 0 Posts
yes, and continues to run when the thermal cutoff activates
 
  #5  
Old 12-16-10, 02:01 PM
SeattlePioneer's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Jul 2007
Location: Seattle, Wa
Posts: 4,469
Upvotes: 0
Received 1 Upvote on 1 Post
When a motor overheats the thermal limit "activates" by opening a switch and shutting the motor off.


Please describe what you are calling a thermal limit.
 
  #6  
Old 12-16-10, 02:01 PM
J
Member
Thread Starter
Join Date: Dec 2010
Location: USA
Posts: 4
Upvotes: 0
Received 0 Upvotes on 0 Posts
to clarify, in the housing of the draft inducer assembly there is a thermal cutoff that is part of the limit switch loop and is replaceable. When the cut off activates the draft inducer motor continues to run but the furnace shuts off (no heat)
 
  #7  
Old 12-16-10, 02:25 PM
SeattlePioneer's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Jul 2007
Location: Seattle, Wa
Posts: 4,469
Upvotes: 0
Received 1 Upvote on 1 Post
Thank you for the explanation.

Can't say that I've seen that kind of limit control before. I would presume the purpose is to shut off the furnace burners if the combustion gasses are too hot, implying a blockage in the furnace or venting system that is preventing the combustion gasses from passing freely into, through and out the furnace and vent.

(If the combustion gasses don't flow freely, they would wind up being too hot. With enough air flow, they would be diluted by the additional air and cooler)

That would be my assumption and reasoning, anyway.

Is there a pressure switch that's a part of the furnace? Usually a pressure switch would check for that kind of condition.
 
  #8  
Old 12-16-10, 06:53 PM
Grady's Avatar
Forum Topic Moderator
Join Date: Jan 2005
Location: Delaware, The First State
Posts: 12,682
Received 41 Upvotes on 39 Posts
S/P,
Much of the equipment on which I work has switches like the one the OP described & yes, your reasoning is correct.
 
  #9  
Old 12-16-10, 07:00 PM
SeattlePioneer's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Jul 2007
Location: Seattle, Wa
Posts: 4,469
Upvotes: 0
Received 1 Upvote on 1 Post
Hey Grady,


Thanks for the benefit of your experience. Is that a recent development in practice?

Do such furnaces use that thermal limit as a substitute for a pressure switch or as an additional safety check?
 
  #10  
Old 12-16-10, 07:10 PM
Grady's Avatar
Forum Topic Moderator
Join Date: Jan 2005
Location: Delaware, The First State
Posts: 12,682
Received 41 Upvotes on 39 Posts
I know some furnaces have used them for years (makes & models I don't recall). I believe the inducer limits are usually a supplemental saftey.
 
  #11  
Old 12-17-10, 06:52 AM
J
Member
Thread Starter
Join Date: Dec 2010
Location: USA
Posts: 4
Upvotes: 0
Received 0 Upvotes on 0 Posts
Thanks for the information and advice. I'll check the venting system for bockages or restrictions.
 
 

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