Robertshaw Ignition Problems
#1
10-06-04, 09:15 AM
Robertshaw Ignition Problems
Hi, can someone help me out. I have a Robertshaw furnace that won't light.
Here's what I do know...
I have spark from the ignition to the pilot light nozzle but the pilot light won't ignite.
The exhaust fan is running
The ignition sequence continues to throw and arc repeatedly eventually timing out.
The gas is ON, the valve on the gas regulator is ON but still no ignition flame.
It's a Robertshaw 7100DER series gas valve and "S" series pilot. I did clean the end of the ignitor and have visually confirmed it has spark.
Any suggestions?
Here's what I do know...
I have spark from the ignition to the pilot light nozzle but the pilot light won't ignite.
The exhaust fan is running
The ignition sequence continues to throw and arc repeatedly eventually timing out.
The gas is ON, the valve on the gas regulator is ON but still no ignition flame.
It's a Robertshaw 7100DER series gas valve and "S" series pilot. I did clean the end of the ignitor and have visually confirmed it has spark.
Any suggestions?
Last edited by ACE&D; 10-06-04 at 10:17 AM. Reason: more detail...
#2
10-06-04, 12:41 PM
Check to see that when it's calling for heat (i.e., when the inducer fan is running and the control is sending the spark) that you have 24VAC across the common (MV/PV) and PV terminals of the ignition control module. If you do, and if you are sure there is sufficient gas pressure going to the gas valve and that the pilot orifice is properly situated relative to the spark, you may have either a broken wire connection or a bad gas valve. You said this control locks out after trying to light the piolt. Is your furnace propane? If so, are you sure you have gas?
#4
10-07-04, 09:56 AM
If while the unit is sparking (which means you are getting 24V to the ignition control) you are not getting 24V across the MV/PV and PV terminals there is either a bad wire or connection, or the ignition control itself has gone south.
#5
10-07-04, 10:00 AM
To clarify, my response refers to the MV/PV and PV terminals on the control module, not the gas valve. If (while sparking) you get 24V across these terminals on the module but not across the C and P terminals of the gas valve, there is fauly wiring between the module and the valve. If you are getting 24V across the C and P terminals of the gas valve but no gas is coming out of the pilot orifice, the gas valve is bad.
#6
10-08-04, 06:05 AM
Okay, thanks for the help. I measured both and I wasn't getting a reading at all from either the MV/PV terminals or the C/P terminals on the gas regulator. Still no gas. So I'll work on replacing the ignition control.
Thank you for your help. You've saved me a lot of money.
Thank you for your help. You've saved me a lot of money.
#7
10-08-04, 06:56 AM
Make sure you have checked everything thoroughly before you buy another ignition control. It seems to me that failure of the ignition control to supply 24V across the MV/PV and PV terminals when sparking would be an unusual failure. What type of control module do you have?
#8
10-11-04, 10:08 AM
I have a Robertshaw Ignition Control. I had a buddy come over and we called for heat and then checked again on the gas regulator. I had 24V across the Pilot terminal (P), but nothing across the Main (M). Upon his expertise we bridge the two and gas started flowing but not out of the pilot light, only out of the main valve. We quickly shut it down.
Interestingly enough I got a quote from the dealer for a new ignition control for $ 169.00. I then called a parts dealer and he quoted me the same ignition control for $ 85.00.
I'm holding out on replacing it (we had a warm weekend). The furnace is 18 years old. Perhaps its time for a replacement, some rust and mineral build up on my heat exchangers and these continuing problems lead me to believe the $ 600 investment might be a good idea.
Your thoughts? Thank you again for your expertise.
Interestingly enough I got a quote from the dealer for a new ignition control for $ 169.00. I then called a parts dealer and he quoted me the same ignition control for $ 85.00.
I'm holding out on replacing it (we had a warm weekend). The furnace is 18 years old. Perhaps its time for a replacement, some rust and mineral build up on my heat exchangers and these continuing problems lead me to believe the $ 600 investment might be a good idea.
Your thoughts? Thank you again for your expertise.
#9
10-11-04, 01:07 PM
Before relegating the gas valve to the trash can, check the pilot orifice and line for obstructions (spiders love to nest in these) that might be preventing gas flow. If the line and orifice are clear, the gas valve is probably bad. Also, deliberately energizing the main valve in the absence of a means to ignite the gas (by jumping the pilot solenoid voltage to the main valve solenoid voltage, as you described) is not recommended.
#10
11-28-10, 06:07 PM
I have a robertshaw ignition control module 780-910......when my heater calls for heat everything works and the furnace comes on but after a couple of second it go out....my control module indicator light flashes one time every couple of second.........can someone tell me what that means? and how do I fix it?
#11
11-28-10, 07:08 PM
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