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Mercury Flame Sensor ( 3-Spade Terminals) * OBSOLETE - SEE DETAILS TO UPGRADE YOUR SYSTEM!

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SKU: FLS30493
(See Product Details Below for Manufacturers Part Numbers)

* OBSOLETE - See Related Products Below to UPGRADE YOUR SYSTEM

White Rodgers Flame Sensor Mercury Switch inserts next to pilot found on many brands of heating equipment.

Capillary (Sensing Bulb) comes in various lengths.
When ordering make sure number of spades 2 - 5 match when ordering new mercury switch.
Capillary Length: 26".

Rating @ 120VAC: 125VA.
Rating @ 240VAC: 125VA.
Rating @ 30VAC: 90VA.
Size: Flame Sensor Mercury Switch inserts next to pilot found on many brands of heating equipment.
Capillary Length: 26"
Used in Older Equipment Models: 42/110 YAC-102AK.

Replaces Part Numbers: 3049-3, F77-3891, CAR30493.


The mercury flame sensor is a mechanical device that proves the existence of an acceptable pilot flame. It converts the heat of a pilot flame to motion which is used to open and close a set of electrical contacts, and consists of a bulb, capillary, diaphram, snap-switch mechanism, and mercury-filled bulb. When the bulb is heated by a pilot flame, the mercury is vaporized causing pressure in the capillary and diaphram. Movement of the diaphram causes the snap-switch to open one set of contacts and close a second set. These contacts control the pilot and the main valve.

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