Brrrr! No Heat! Please Help!

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  #1  
Old 10-11-07, 10:59 AM
J
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Exclamation Brrrr! No Heat! Please Help!

Hello- I'm hoping someone may be able to help me out?

I have an older model commercial Carrier
58SE Deluxe Gas-Fired Forced-Air Furnace with Intermittent Pilot Ignition Device.

Everything seems to be working in proper sequence i.e., thermostat calls for heat, relay turns on blower, automatic pilot light ignites, but the main burners never fire. After a few minutes the pilot light kills itself because there is no gas to the main burners. Is there a sensor that releases the gas when it acknowledges the pilot is lit. I know like in my gas stove there is a "flame ignitor" but they didn't start putting those in furnaces until 1992 and this is a 1984 model. Is there some kind of thermocouple that has failed or pilot sensing probe. If anyone has information on this old dog I would greatly appreciate it or if you know somewhere I might find info that would be great too!


Thanks-Joe
 
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Old 10-11-07, 11:18 AM
J
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Sounds like the old spark box. I don't care for those too much.
OK, when the pilot lights, the flame sensor tells the controls to open the main gas valve. Some units have two rods, one for the spark and one for flame sensing. In others, the same rod does both jobs. If the rod is dirty, or coated with dust, carbon, corrosion, etc., the flame will not be sensed. The controls will shut down.

Solution: clean the flame sensor with fine steel wool or just replace it. Make sure all connections are clean and tight. Also, the grounding is critical. remove the pilot bracket mounting screws and clean all surfaces. Remember, we are talking about microamps. It doesn't take much to throw things off.

In most cases the above will solve the problem. In other cases, the control module or gas valve can go bad.
 
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Old 10-11-07, 11:23 AM
J
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Thanks Jim

Hi Jim,

Is there a flame sensor even on that old model? Do you know where it is located? Is
it like a long thin rod?

Thanks for your feedback!

Joe
 
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Old 10-11-07, 11:46 AM
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The flame sensor is a long thin metal rod with a ceramic insulator at the base. It's located at the pilot.
 
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Old 10-11-07, 01:29 PM
D
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pick and hold system

Originally Posted by joeraccio View Post
Hello- I'm hoping someone may be able to help me out?

I have an older model commercial Carrier
58SE Deluxe Gas-Fired Forced-Air Furnace with Intermittent Pilot Ignition Device.

Everything seems to be working in proper sequence i.e., thermostat calls for heat, relay turns on blower, automatic pilot light ignites, but the main burners never fire. After a few minutes the pilot light kills itself because there is no gas to the main burners. Is there a sensor that releases the gas when it acknowledges the pilot is lit. I know like in my gas stove there is a "flame ignitor" but they didn't start putting those in furnaces until 1992 and this is a 1984 model. Is there some kind of thermocouple that has failed or pilot sensing probe. If anyone has information on this old dog I would greatly appreciate it or if you know somewhere I might find info that would be great too!


Thanks-Joe
Carrier furnaces from that era used a thermal sensing pilot safety switch which has 2 or 3 wires going to a switch that is actually part of the pilot burner assembly. Most of them have 3 wires and are coloquially known as the 3-wire pilot. Look very closely at the pilot burner. Do you see a small switch looking device there with 3 wires, yellow, white and green? If so, the most common failure is the switch won't switch from the cold to the warm position when the pilot flame heats it up. You can buy a replacement pilot burner/switch assembly online. Be careful to not lose the pilot burner orifice when you replace the assembly. Arnold's hvac parts online has them, about $70 plus tax and shipping.
 
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Old 10-11-07, 01:53 PM
J
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Thanks for the feedback Daddyjohn. It's pretty old furnace! Probably not too energy efficient? I'll check it out tonight.
 
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Old 10-11-07, 02:10 PM
J
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Hey DJ-Are there any points I can check voltsges with a mutlimeter to verify if this switch is functioning?
 
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Old 10-12-07, 05:50 AM
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Originally Posted by joeraccio View Post
Hey DJ-Are there any points I can check voltsges with a mutlimeter to verify if this switch is functioning?
Did you look to see if the pilot does in fact have a pilot safety switch? if yes, how many wires? 2 or 3?
 
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Old 10-12-07, 06:26 AM
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Hey Daddyjohn. Just wanted to say Thanks!
It's a 3-Wire switch and I checked it out with my meter last night and it's NOT functioning properly. I called the local supply shop this morning and they have one for $65 bucks. Hopefully by late this afternoon heat will be flowing!

Thanks for everyone's help!

Joe
 
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Old 10-13-07, 01:00 PM
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Originally Posted by joeraccio View Post
Hey Daddyjohn. Just wanted to say Thanks!
It's a 3-Wire switch and I checked it out with my meter last night and it's NOT functioning properly. I called the local supply shop this morning and they have one for $65 bucks. Hopefully by late this afternoon heat will be flowing!

Thanks for everyone's help!

Joe
Sounds good! Let us know how you make out. Thanks.
 
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