Another burner question

Reply

  #1  
Old 01-29-03, 02:42 PM
jevoman
Visiting Guest
Posts: n/a
Another burner question

This is another question similair to ones previously posted. I have a Comfortmaker Model # NDN6075FBA1 Gas Forced Air Furnace with an electronic ignition system. A few days ago the burners stopped igniting. I turned the gas valve switch off and then back on and it worked properly for a few days and then the same problem. The first blower starts, the pilot comes on, no burner ignition, then the main blower starts. I removed the senson rod and sanded it clean, but the problem remains... Any suggestions would be appreciated...thanks!!!
 
Sponsored Links
  #2  
Old 01-29-03, 04:14 PM
bigjohn
Visiting Guest
Posts: n/a
Check these things:

1. Are you getting voltage to the gas valve terminals?

2. Does the pilot flame envelop the flame rod?

3. Check for O continuity from the flame rod tip to the sense terminal on the ignition module.

4. Check for infinite resistance from [no continuity] from the flame rod to ground.

5. Ensure that ALL the ground connections in the furnace are clean/tight.

6. What is the brand and model # of the ignition module?
 
  #3  
Old 01-29-03, 06:11 PM
jevoman
Visiting Guest
Posts: n/a
Thanks for your help Big John.

The Ignition Module is a Honeywell SV9501M.

I will check for those things when it stops working again. It seems to be very touchy though. This morning (when the burners weren't working, I pulled the cover off and it shut down (safety switch) I then held the switch in by hand and when it kicked back on, the burners lit. I have the switch taped now so I can pull the cover off without disturbing anything. I checked the sensor rod to 24v common when off and it was 0 and held it on when the pilot lit and it rose to about 119v. I will recheck it when its not working. Thanks again.
 
  #4  
Old 01-30-03, 07:29 AM
bigjohn
Visiting Guest
Posts: n/a
Your furnace has the Honeywell Smart Valve Gas Control System. Notice how the pilot buner assembly is wired back to the gas valve? The ignitoin module is built into the housing atop the gas valve. This system uses a Hot Surface Igniter to lite the pilot. It also uses the pilot burner gas tubing for grounding. Here are some things to check that are specific to the SV system:


1. See the hood over the pilot burner assembly? Make that it IS NOT touching the flame rod. Don't bend it too far away, .05 inches is the minimum clearance. [.05 is like 50/1000. If you have one of those tools for gapping spark plugs- the kind with the round feeler guage- you could use that to check it or just eyeball it.]

2. The pilot flame wants to envelop the flame rod tip and the hood. Like other furnces, the SV system uses flame rectification to prove the pilot flame.

3. The spot where the pilot burner assembly attaches wants to be clean. IOW- underneath the pilot burner assembly bracket as well as the underside of the bracket. Clean both surfaces with a wire brush and ensure that the assembly is securely attached.

4. Shut the furnace off and let everything cool down to room temperature. Check the resistance of the Hot Surface igniter. At room temp it sould be 10 ohms or less.

5, Ensure that the flame rod and hood are clean.

6. Check the resistance from the flame rod tip to ground. You should get infinite resistance. [this verifies the integrity of the ceramic insulator on the flame rod]

7. Ensure that ALL ground connection sin the furnace are clean/tight.
 
  #5  
Old 02-07-03, 03:57 AM
jevoman
Visiting Guest
Posts: n/a
I was out of town for a week and came back to find my furnace not working again. I cleaned (twice) the sensor rod and all the brackets as you suggested. When I arrived back, it was still doing the same problem. The inducer fan turns on, the pilot lights, and the blower kicks on (after a few seconds), but no burner ignition. I checked the voltage across the proper terminals at the 'smart valve' and it is getting the call to send the gas to the burners (approx 25v across black/white at all times-----0 volts across orange/white when the furnace is not on and approx 26 v across the same terminals after pilot ignition) While cleaning the sensor rod, I noticed that is slightly loose inside its ceramic 'boot', I was going to replace it, but the guy at the parts store looked at it and said it was OK (the ceramic is intact, but the rod will turn slightly, if you try--resistance was OK when checked to ground) Should I assume it is the gas valve??

Thanks in advance !!
 
  #6  
Old 02-07-03, 06:07 AM
jevoman
Visiting Guest
Posts: n/a
I should add that turning the valve off for about 10 minutes and turning it back on will make everything work properly for a few days. I also noticed in another post, the issue of having a Honeywell programable thermostat came up (I have one) but, since the call for heat is occuring, the blowers are turning on, and the voltage is getting to the valve, I would have to guess that it is not a thermostat problem.
 
  #7  
Old 02-07-03, 02:05 PM
bigjohn
Visiting Guest
Posts: n/a
The terminals you're reading aren't exactly at the valve operator. The ones for the operator are under the cover and may inaccessible. I believe I would change that loose flame rod unless maybe the parts guy invites your family to sleep over at his warm house? What if the rod is turning away from the flame when it's hot? That might interrupt the flame proving circuit.
 
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