furnace not starting

Reply

  #1  
Old 01-07-10, 01:58 PM
sgull's Avatar
Member
Thread Starter
Join Date: Nov 2007
Location: AK
Posts: 2,889
Received 1 Vote on 1 Post
furnace not starting

I noticed one of our oil-fired furnaces isn't starting. The motor doesn't even begin to start. The red reset button on the primary control isn't popped out. The breaker isn't tripped. We have one of those programmable on-the-wall electronic thermostats like this one http://i207.photobucket.com/albums/b...1/IMG_1293.jpg
which is the Honeywell model RTH230B. It's set so that this furnace should turn when a particular area gets below 68 degrees, but like I said the furnace never starts and the room gets cold. The primary ignition control unit at the furnace is a Honeywell model R8184 G 4009 like this one http://i207.photobucket.com/albums/b...1/IMG_1295.jpg. I took a hand-held electrical current indicator tool like the one in the picture and held at each of the four terminals along the side of the control, but at only one of the thermostat terminals (out of the two) will any current be indicated by the tool. The other two terminals on the control are for the flame sensor, and no current is indicated at those terminals either.
We have another identical furnace with an identical primary control which will indicate current (using the tool) at all four terminals even when the furnace motor is not running. (This identical furnace heats a different area and uses a different thermostat.)
I'm wondering if someone might be able to tell me with this information whether I may have a bad primary control or maybe the thermostat gave out, or what further I might need to check to troubleshoot the issue.
 
Sponsored Links
  #2  
Old 01-07-10, 03:41 PM
P
Member
Join Date: Feb 2007
Location: Brantford Ontario Canada
Posts: 117
Received 0 Votes on 0 Posts
Start by jumpering the two "T" terminals. If the burner still doesn't start, remove one of the "F" wires while the jumper is still attached and see if it will start. You should only have 24 volts on one of the t terminals. If you trip the reset does the red light come on?
 
  #3  
Old 01-07-10, 04:14 PM
sgull's Avatar
Member
Thread Starter
Join Date: Nov 2007
Location: AK
Posts: 2,889
Received 1 Vote on 1 Post
Originally Posted by pfd27 View Post
Start by jumpering the two "T" terminals. If the burner still doesn't start, remove one of the "F" wires while the jumper is still attached and see if it will start. You should only have 24 volts on one of the t terminals. If you trip the reset does the red light come on?
Okay, I jumpered the two "T" terminals and the burner started. Then, while the jumper was still attached, I removed one of the "F" terminals, and it still would start but then in 15 seconds or so the reset button tripped, and the red light would come on. What might this mean, what further should I do next? thanks
 
  #4  
Old 01-07-10, 04:26 PM
P
Member
Join Date: Feb 2007
Location: Brantford Ontario Canada
Posts: 117
Received 0 Votes on 0 Posts
Originally Posted by sgull View Post
Okay, I jumpered the two "T" terminals and the burner started. Then, while the jumper was still attached, I removed one of the "F" terminals, and it still would start but then in 15 seconds or so the reset button tripped, and the red light would come on. What might this mean, what further should I do next? thanks
Jumpering t&t simulates a call for heat. Removing the f while t was jumpered eliminates a shorted flame sensor. Since the control locked out with the f removed it looks like all is well at the furnace end.
Hook the f back up and reset the control. You likely have a bad thermostat, but before you replace it I would pop the stat off the wall and jumper R & W at the stat. If the burner starts you have something wrong with the stat, if not you have a break in the wires going to the burner.
 
  #5  
Old 01-07-10, 04:47 PM
sgull's Avatar
Member
Thread Starter
Join Date: Nov 2007
Location: AK
Posts: 2,889
Received 1 Vote on 1 Post
Originally Posted by pfd27 View Post
pop the stat off the wall and jumper R & W at the stat. If the burner starts you have something wrong with the stat, if not you have a break in the wires going to the burner.
I popped the stat off the wall and saw that the terminals there include W and not an R but actually an Rh (I believe for heating power supply) and an Rc (for cooling power supply probably, but we have no cooling system here). The red wire was connected to the Rh but nothing connected to the Rc. Anyway I jumpered between the W terminal and both the Rh, but the burner never started. So I suppose that means I have a break in the wires going to the burner? Fun! How do I find where it's broken?
 
  #6  
Old 01-07-10, 05:25 PM
P
Member
Join Date: Feb 2007
Location: Brantford Ontario Canada
Posts: 117
Received 0 Votes on 0 Posts
Originally Posted by sgull View Post
I popped the stat off the wall and saw that the terminals there include W and not an R but actually an Rh (I believe for heating power supply) and an Rc (for cooling power supply probably, but we have no cooling system here). The red wire was connected to the Rh but nothing connected to the Rc. Anyway I jumpered between the W terminal and both the Rh, but the burner never started. So I suppose that means I have a break in the wires going to the burner? Fun! How do I find where it's broken?
Rh and w... my mistake Disconnect the wires from the stat and twist them together just in case you didn't have a good connection and see if the burner starts. If not it looks like you're running a new stat wire

You could try cutting the cable in the basement where it comes through the floor and cross the wires going to the furnace. You might get lucky and the break is in the basement and not the wall.

Pulling a new cable isn't as hard as it sounds as long as someone hasn't stapled it to a stud inside the wall .
 
  #7  
Old 01-08-10, 04:28 PM
P
Member
Join Date: Feb 2007
Location: Brantford Ontario Canada
Posts: 117
Received 0 Votes on 0 Posts
Let us know if you got the furnace working
 
  #8  
Old 01-08-10, 05:04 PM
sgull's Avatar
Member
Thread Starter
Join Date: Nov 2007
Location: AK
Posts: 2,889
Received 1 Vote on 1 Post
Originally Posted by pfd27 View Post
Let us know if you got the furnace working
Yes, got the furnace working. Traced the thermostat wires from the furnace and found that they went to ANOTHER thermostat which monitors the temperature inside the ductwork leading to the area the furnace heats. That thermostat was turned down, and when I turned it up the furnace started. The programmable thermostat in the area the furnace heats is apparently disconnnected or otherwise non-functional for an unknown (to me) reason.

Thanks for all your helpful input pfd27
 
  #9  
Old 01-08-10, 09:00 PM
P
Member
Join Date: Feb 2007
Location: Brantford Ontario Canada
Posts: 117
Received 0 Votes on 0 Posts
Originally Posted by sgull View Post
Yes, got the furnace working. Traced the thermostat wires from the furnace and found that they went to ANOTHER thermostat which monitors the temperature inside the ductwork leading to the area the furnace heats. That thermostat was turned down, and when I turned it up the furnace started. The programmable thermostat in the area the furnace heats is apparently disconnnected or otherwise non-functional for an unknown (to me) reason.

Thanks for all your helpful input pfd27
That's really weird. Glad you got it working
 
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: