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  #1   IP:
Old December 8th, 2005, 08:48 PM
Chilly Willy Chilly Willy is offline
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Location: CANADA
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Default Armstrong Ultra SX 80 – Intermittent Burner Control

Armstrong Ultra SX 80 – Intermittent Burner Control

I am looking to you for help on this one. It has me and the service tech scratching our heads. I have a 6 year old Armstrong Ultra SX 80 force air gas furnace that intermittently does not ignite the main burners.

Service History:
Oct 2005 – turned on the furnace for the first time, the ventilator turned on, the hot surface ignition lit the pilot and that was it. Technician came out verified the complaint took out the flame sensor and cleaned it with sandpaper reinstalled it and it fired up (system – operational or so we thought).

Nov 2005 – furnace was cycling but intermittently would not ignite the main burners once again. Tech came out cleaned flame rod sensor again, replaced pilot envelope assembly (390686-4) and the system worked once more.

Nov 2005 – furnace intermittently cycled and would not ignite main burners. Replaced the flame rod sensor and system was up and running again.

Nov 2005 – a week later, same problem. Tech says it is most likely the smart valve but if it was the smart valve it would not operate at all. (I have a Honeywell SV9502H 1706)

Oddly enough every time the tech worked on the furnace I would turn it off at the thermostat. In checking the flame rod sensor, pilot envelope and the operation if I were to turn the system off and let it sit for 10 minutes and turn it back ON the furnace would cycle through the sequence and the main burners will ignite and the furnace will operate (for a little while, anyways). Is it the smart valve??? Is the new flame rod sensor defective?? I don’t have a micro-Amp circuit tester to test it.

One more piece to the puzzle. . . Sometimes when the furnace is “operational” it ends the sequence (say at 66’F) before the house reaches the set temperature on the programmable thermostat (70’F).

As I write this posting the furnace just cycled and the main burners did NOT ignite. The ventilator motor runs, the pilot is lit, and the main furnace blower motor and air cleaner is running BUT NO main burner.

I look forward to all responses and your help in solving this problem.
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  #2   IP:
Old February 20th, 2006, 06:58 AM
helpme helpme is offline
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Join Date: Feb 2006
Posts: 1
Default I have the same exact problem

As I was searching the internet for a solution to my furnace problem, I came across your thread. I have the exact same furnace and vlave and have been experiencing exactly the same problems you have described. We had our unit serviced and the ignition assembly replaced and still we have the same intermittent problems. We have also been told that it could be the valve so that was going to be my next step but it's so expensive. Did you ever find a resolution?
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  #3   IP:
Old February 23rd, 2007, 01:16 PM
heatinept heatinept is offline
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Default same problem

Did you ever get a reply. If not maybe someone will see this and reply.
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Old February 23rd, 2007, 02:19 PM
sloooo sloooo is offline
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Join Date: Oct 2006
Location: Redlands, California
Posts: 789

I have seen this problem way to many times. The smart valve isn't very smart. When you have problems with them, you will continue to have problems. Here is a link to buy a new one, if you need it.


But, before you do, go to your thermostat and jumper together the red and white wire. This will take your thermostat out of the loop. If it still does it, then your themostat is OK. If it stops your problem, your thermostat relay is chattering. You'll need to replace the thermostat.

When the technician was out before, did he check all the safety switches to make sure one isn't triped?
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  #5   IP:
Old October 17th, 2009, 08:16 AM
chuckz01 chuckz01 is offline
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Default Did you replace the Smartvalve?

Hey Chilly Willy or Helpme. I have the same problem and am at the point where the Smartvalve is next. Did either of you fix your problem by replacing the Smartvalve? Thx, Chuck Z.
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  #6   IP:
Old November 1st, 2012, 03:00 PM
siggyd siggyd is offline
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Default Ultra SX 90 No Main Burner

I have the exact same problem as Chilly Willy, main valve SV9502H 1706
Ignition ok,flame ok,but no main burners, it's intermittent !
Switch OFF all power...it may work ok for a day or more.
Sometimes the main burner shuts OFF before the target temperature is reached.
The main filter is CLEAN, HEAT blower fan is set to LOW (red wire).
The Igniter Q3400A 1016 has been replaced 6 months ago.
Like I said before,the problem is very intermittent,calling a technician is
useless,because it will most likely work.
HELP, Siggy

Last edited by siggyd : November 1st, 2012 at 08:00 PM.
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  #7   IP:
Old November 18th, 2012, 07:06 AM
CapeFear CapeFear is offline
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Location: Wilmington NC
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Was there any flash sequence from the valve?
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Old November 19th, 2012, 02:23 PM
CJC CJC is offline
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Posts: 1
Default Can I just replace the circuit board on the smart valve

I have the same problem with my furnace , sometimes after pilot ignites and I tap on the smart valve after I hear the click the main burners will ignite. I have heard it is a faulty board (common problem). Can I just replace circuit board ? If I do have to replace Smart Valve is it factory set for gas pressure or will I have to have a tech install it ? Thanks in advance.
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