Heater Ignition Problem

Old 10-20-02, 05:54 PM
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Angry Ignition partially working for gas furnace (heater)

Got a Trane home central heater. When turned on the air blower works and a little later some clicking sound leads to the right ignition coil turning into red. Hower, the on on the left remains "cold". The one on the right has 2 black wires connecting to a Fenwal "automatic ignition system" box and the left one has one white wire connected to the box. The right one is big and looks complex while the left one is just a thin metal stick (nothing else). At this time I guess the gas valv didn't open due to not detecting the left ignition lighted?

Any advice appreciated.
Old 10-20-02, 06:34 PM
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Hello billcai and Welcome to the Do-It-Yourself Web Site.

Not sure what you mean by the one on the left remains cold?
Are there two glow hot surface ignitors? The one on the right is connected to a box? What box? Confused

The glowing bar or coil is the hot surface ignitor. If this is glowing a brit yellow orange color, most likely it's functioning properly.

The thin stick rod must be the flame sensor element, if I presume correctly. If there isn't any flame comming into contact with it, it will shut the gas valve off.

If flames are comming into connect with it but the burners do not lite or remain on, most likely the sensor is dirty, there is a poor electrical connection or contact at the terminal ends.

Clean the flame sensor {thin rod element} with fine grit sand paper or steel wool. Unscrew the screws that attach the terminal ends of the wire terminals that are grounded to the furnaces metal frame.

Clean the surfaces and reattach exactly as you find them and retest the furnace operations. Be sure to unplug or turn off the electrical power before attempting any repairs.

An excellent source for orginal replacement parts is your local retail appliance parts store, the local heating dealers and agents retail part stores. Bring the make, model and serial numbers. The info will help to determine the possible problem causes. These businesses test and carry replacement parts. There Locations are listed in the phone book.

Read the RECENT postings within this forum on heater topics and the replies offered. Doing so will provide additional information.

If you need further assistance, use the REPLY button to add any additional information or questions. Using this method also moves the topic back up to the top of the list automatically.

Regards & Good Luck, Forum Host & Moderator.
TCB4U2B2B Company Enterprises. Energy Conservation Consultants & Gas Appliance Diagnostics Technicians.
Old 10-20-02, 08:59 PM
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Hi Tom,

Thanks for the quick and informative reply. I also went through the recent posts from the forum before I posted the last one.

It looks like, what you described, the one on the left is the sensor.

The system has 2 gas outlet. There is an ignition bar in front of the right gast outlet and the left outlet has the sensor (looks like). Both the sensor and the ignition have wires connected to the "box" - Fenwal Automatice Ignition System.

I had followed your advice in taking out the sensor and cleaned it with a piece of sand paper. Put it back in there and it still not working. The symptom is that the right ignition bar will turn to bright orange color a short moment after the furnance was turned on. It seems like that the sensor is not getting a signal from the ignition bar on the right so that there is no gas being allowed to flow to the outlets?

Is the sensor supposed to detect the hot ignition bar?

Like you suggested I might go to a local appliance store to check things out...



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