furnace keeps shutting down mid cycle - electrodes appear sooted

Reply

  #1  
Old 02-09-13, 10:15 PM
Member
Thread Starter
Join Date: Nov 2011
Location: USA
Posts: 97
Received 0 Votes on 0 Posts
furnace keeps shutting down mid cycle - electrodes appear sooted

heres an older pic I took of the electrodes inside. I've since re-adjusted them a bit so they sit higherName:  IMG_0476.jpg
Views: 774
Size:  23.2 KBName:  IMG_0477.jpg
Views: 846
Size:  27.3 KB

I question the condition of them, as well as the curve in their tip, all of the images I've seen online so far have straight bends as up posed to the curve, and they angle towards each other upposed to pointing like these do.
the soot is allways generally hanging between the two tips.
 
Sponsored Links
  #2  
Old 02-10-13, 06:56 AM
hvactechfw's Avatar
Member
Join Date: Jan 2011
Posts: 6,245
Received 0 Votes on 0 Posts
Those look WAY to far from the nozzle to me. I don't do a lot of oil though. Wait for Grady to chime in.
 
  #3  
Old 02-10-13, 04:22 PM
Grady's Avatar
Forum Topic Moderator
Join Date: Jan 2005
Location: Delaware, The First State
Posts: 13,928
Received 0 Votes on 0 Posts
Grady, the old oil burner geezer is here. Electrode tips should be NO more than 1/2" above the nozzle. I prefer to keep them around 7/16". They should also be no more than 1/8" in front of the nozzle face & 1/8" apart.

That is an OLD burner. What make? Electrodes look like a Nu-Way.
If that burner is in a furnace (not boiler) I'd have the heat exchanger checked.
 
  #4  
Old 02-10-13, 10:58 PM
Member
Thread Starter
Join Date: Nov 2011
Location: USA
Posts: 97
Received 0 Votes on 0 Posts
the burner is a bottom firing. the electrodes are about 3/8 away from the nozle, 1/8 above it , and about 1/8 gap currently.

I have been suspicious of the heat ex changer given the furnace vibrates/rattles in that area when it's first starting up.
Guess after I force it through this year I'll have to retire it.

What is a good price/reliability balanced brand for a lowboy furnace ? I want to adapt it to my current duct work.

the furnace is in the basement, and the house has two Upper stories. The plenium currently has 5 branches out of it.
 
  #5  
Old 02-11-13, 06:51 PM
Grady's Avatar
Forum Topic Moderator
Join Date: Jan 2005
Location: Delaware, The First State
Posts: 13,928
Received 0 Votes on 0 Posts
You may be getting the electrodes into the spray pattern of the nozzle. Set the electrodes as follows & try it. 7/16" above the nozzle center, 1/16 to a max of 1/8" ahead of the nozzle face, & a fat 1/8" gap.

There are several decent oil fired lowboys out there. Top of the heap is Thermo-Pride. Boyertown Furnace makes good stuff as well (Rheem is now made by Boyertown). Armstrong or Ducane aren't bad nor is Heil or Tempstar.
 
  #6  
Old 02-11-13, 10:29 PM
Member
Thread Starter
Join Date: Nov 2011
Location: USA
Posts: 97
Received 0 Votes on 0 Posts
I should probably note that this furnace fires oil upwards out of the bottom of the chamber as upposed to the burner itself.
I adjusted the electrodes so they are 1/16 (also tried 1/8) above the nozzle height/face 7/16 away from and 1/8 apart.

when the electrodes were 1/8 above the nozzle they sooted very fast and the furnace refused to restart until I cleaned them.

also furnace seemed to run longer when I had the tips gaped at 1/4th apart

The furnace is still shutting off the burner after running approx 5 -10 minutes.
the electrodes still appear sooted but the furnace restarted with the reset 19/20 times.
the airflow (house side blower continues to run till the unit is cool)

The unit appears to be burning when It trips the stack reset.

could the electrodes be setup so their tips are flush height with the nozzle?
 

Last edited by kiyolaka; 02-11-13 at 11:16 PM.
  #7  
Old 02-12-13, 07:37 PM
Grady's Avatar
Forum Topic Moderator
Join Date: Jan 2005
Location: Delaware, The First State
Posts: 13,928
Received 0 Votes on 0 Posts
Once the flame ignites, the ignition system (electrodes), should be out of the picture. With most OLD equipment and all new burners the ignition drops out after flame is proven. You have another problem besides the electrodes. Without being able to spend time with it & see first hand what the burner is doing, it's going to be darned tuff to trouble shoot. Do you have a volt meter & know how to use it?
 
  #8  
Old 02-12-13, 08:41 PM
Member
Thread Starter
Join Date: Nov 2011
Location: USA
Posts: 97
Received 0 Votes on 0 Posts
Yes, I do electronics repair as a bit of a hobby/cheap way to fix stuff and get it for my house.
I also happen to own a cheap Endoscope.

before we go too much further could a restricted/failing heat ex changer be the issue?
When I vaccumed the stack duct it was absolutely filthy, had about 3/8 of an inch of slit throughout the entire thing, and the stack control spring was sitting almost directly on the stuff.
so it would not surprise me if the heat ex changer is full of it too.

Other than that my uneducated guess is perhaps the stack control unit is malfunctioning?
 
  #9  
Old 02-13-13, 05:37 AM
Member
Join Date: Jan 2010
Location: Maryland
Posts: 415
Received 0 Votes on 0 Posts
Just checking. Have you checked you oil supply. If the furnace comes on and rumbles that may be your problem. You need a nice clean oil supply with no air in the line and the pump pressure should be between 90 and 100 psi.
 
  #10  
Old 02-13-13, 11:39 AM
Member
Thread Starter
Join Date: Nov 2011
Location: USA
Posts: 97
Received 0 Votes on 0 Posts
Psi is approx 97 when I last checked. I've bled the system quite a bit at the pump as well as at the filter. as well as replaced the tubing between the pump and nozzle (old flare had small crack in it.
pump strainer,nozzle and filter cartrige are all new.

It does still occasionnaly rumble though, especially if I turn down the burner airflow (currently its at approx 80% of its max)
 
  #11  
Old 02-13-13, 04:31 PM
Member
Thread Starter
Join Date: Nov 2011
Location: USA
Posts: 97
Received 0 Votes on 0 Posts
I gave up and have a pro coming to look at it on Friday. If I spend much more time with it I am likely to snap and rage on it.
 
  #12  
Old 02-13-13, 05:05 PM
Member
Join Date: Nov 2011
Location: USA
Posts: 699
Received 2 Votes on 2 Posts
Sounds like you need the complete vac. and brush,clean and restep stack stack relay if not a new one,adjustments of electrodes and burner. Your better off, it looks like a mess.
 
  #13  
Old 02-15-13, 06:36 PM
Member
Thread Starter
Join Date: Nov 2011
Location: USA
Posts: 97
Received 0 Votes on 0 Posts
stack control was toast, replaced and have not had an issue since.

also appearantly with this particular furnace being a one of a kind bottom vortex burner design, it has a bit of a unique gaping for the electrodes. Closer to 1/2 from nozzle center (it fans out more than 80* due to the vortex airflow) Flush with the nozzle height wise, and slightly more than 1/8 gap.
 
  #14  
Old 02-15-13, 06:50 PM
Member
Join Date: Nov 2011
Location: USA
Posts: 699
Received 2 Votes on 2 Posts
Hi Kiyolaka, did you have it brushed and vac.? Sounds like you made out pretty good.Save up for that new one though.
 
  #15  
Old 02-16-13, 03:42 AM
Member
Thread Starter
Join Date: Nov 2011
Location: USA
Posts: 97
Received 0 Votes on 0 Posts
Yeah, atleast its not an urgent matter now.
I vaccumed out the stack
+ bottom of chimney. What sort of brush would one use?
 
  #16  
Old 02-16-13, 02:51 PM
Member
Join Date: Nov 2011
Location: USA
Posts: 699
Received 2 Votes on 2 Posts
Depends on how wide and long your passages from flame to smoke pipe are.The softer the bristles the less in your eye.Maybe get the gray furnace cement too.Good luck.
 
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
Display Modes
 
Ask a Question
Question Title:
Description:
Your question will be posted in: