Does anyone know what the resistance should be on the igniter? My heater quit working and was getting an open, so I installed a new igniter and it’s not working either. I failed to check the resistance before installing, but after failing to light the resistance is open again. I measured the voltage and got a reading of 135ac. Could that be blowing the igniters? Suggestions?
JXI 400 Igniter Resistance
- Thread starter Nkepmkep
- Start date
swamprat69
Well-known member
Not sure about the specific ignitor used in the Jandy, but the Supco round (spiral style) ignitor used in residential furnaces is ~ 40-100 ohms cold and operates at ~ 120V.
Thank you. Do you think the 135ac at the terminals could be breaking the ignite? The manual states a range up to 130, so I would think it should still be ok.
swamprat69
Well-known member
Most parts specs allow a differential of + or - 10%. This would put max voltage at 132 volts. This would put the variance from max voltage at just over 2%. While this would definitely shorten the life of the ignitor somewhat, I don't think that it would be a cause for repeated catastrophic failures. Silicon carbide ignitors are both somewhat fragile physically ( from a physical shock like accidentally bumping it against a hard surface) and also prone to fail from surface contamination before installation (like touching the ignitor surface with your hands).
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If you measure any connectivity at all on your ignitor, chances are it is working. When they fail, they crumble apart.
You can check the amperage going to the ignitor with a clamp ammeter or an inline ammeter.
If the amperage is exceeding 5 amps, then the ignitor might be getting too hot from excessive voltage.
You might need a true RMS meter to get a good read on the voltage because of how the 120 volt voltage is supplied when the unit is connected to 240 input supply.
If the amperage is exceeding 5 amps, then the ignitor might be getting too hot from excessive voltage.
You might need a true RMS meter to get a good read on the voltage because of how the 120 volt voltage is supplied when the unit is connected to 240 input supply.
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Thank you all. I’ll check the amperage. Definitely not getting any connectivity on the ignite, so did order another one.
Put in new igniter today, and it's working! This time I checked the ignitor's resistance before installing. Unfortunately, I'm not sure if I received a bad igniter the first time, or I damaged it when I installed it.
I didn’t have an ammeter, so I just decided to give it a shot. I put one on order and will check it when it comes in. Hoping the first replacement igniter was just bad.