Carrier Flow Sensing Switch


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Old 02-13-09, 10:25 AM
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Carrier Flow Sensing Switch

http://www.xpedio.carrier.com/idc/gr.../58ss-6sic.pdf


As I've been replying to questions about Carrier furnaces, it occurs to me that I'm not exactly clear as to how the Carrier flow sensing switch (Part7V) operates on furnaces like the Carrier 58SS, Payne BAW and other similar furnaces that have a separate inducer control circuit board.

This isn't the pressure switch on these furnaces. It's a switch of some kind that energizes the hold coil of the gas valve at the time the inducer motor is switched on, or perhaps at a slightly later time.

But there is no way apparent to me that the inducer relay circuit board can verify that the inducer motor has started.

So who can describe just what this switch is sensing and how it's turned on?

I'm guessing that it's simply energized when the inducer motor is energized, but perhaps I'm wrong.
 
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Old 02-13-09, 11:07 AM
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It works off of negative pressure through the HX...inducer comes on and sucks it closed
 
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Old 02-13-09, 11:31 AM
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Oh, yes, Dun11. I was thinking that one of the other switches was the pressure switch, but you are correct.


I've been away from doing furnace repairs in the field for several years now, and my memory of that detail had faded, or failed.

Thanks for the reminder.
 
 

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