Lenox WhisperHeat SP745 - Damper door will not fully open

Reply

  #1  
Old 01-02-10, 06:07 PM
J
Member
Thread Starter
Join Date: Jan 2010
Location: Iowa
Posts: 1
Received 0 Votes on 0 Posts
Exclamation Lenox WhisperHeat SP745 - Damper door will not fully open

Hello!

I am a new home owner of a year, and have rencently been having furnace problems. It is a WhisperHeat SP 745 (maybe 13 years old...)

I believe, what is called, the damper door (automatic door right infront of the pilot light) will not stay open. It will slowly open on its own, clicking and jumping back a few times. Then right as the pilot light starts to burn, it will slam closed, turning off the pilot. If I assist the door but not letting it snap closed, it will light up and run correctly, until the next time the furnace needs to turn on, it starts this problem all over.

I would guess that a tech could solve this problem right away, but I am hesitant to have some one come out till I am familiar with the problem. They tend to find other 'things' that need replaced, when I could get by with a simple solution.

Any input would be greatly appreciated!
 
Sponsored Links
  #2  
Old 01-02-10, 07:34 PM
SeattlePioneer's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Jul 2007
Location: Seattle, Wa
Posts: 5,503
Received 0 Votes on 0 Posts
If you have an AC voltmeter I'd check to see if the thermostat is shutting off the furnace.

Another way to test that would be to connect the R and W terminals on the circuit board together with a wire, which is what the thermostat does when it calls for heat.

If the thermostat is the problem the furnace will operate normally when the jumper wire is connected.
 
  #3  
Old 01-03-10, 10:36 AM
Skip4661's Avatar
Member
Join Date: Dec 2008
Location: West Michigan
Posts: 298
Received 0 Votes on 0 Posts
I would suspect the damper drive motor has stripped its gears.
Until the motor can be replaced you can carefully remove the damper and jump the damper open proving switch to get you some heat. The purpose of the door is to gain 2% efficiency so the furnace could be sold legally as an 80% efficient furnace.
 
  #4  
Old 01-03-10, 11:50 AM
SeattlePioneer's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Jul 2007
Location: Seattle, Wa
Posts: 5,503
Received 0 Votes on 0 Posts
Skip's suggestion that the door opening mechanism is defective is probably right. That would account for the erratic operation described.

However, it could be that the thermostat isn't staying on properly. Jumping out the thermostat to check on that is a cheap way to eliminate that as a problem.
 
Reply
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


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