Help with wiring mercury switch

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New Member
Nov 15, 2021
Vancouver, WA.
I have a Comfortec CDV36RP gas fireplace on which I recently replaced the gas valve. The gas valve is a Robertshaw as shown in the attached picture. The fireplace also has a mercury switch which is similar to the one shown in the attached picture.

My situation that requires assistance is regarding the two wires that come off the mercury switch. In my haste to replace the gas valve, I didn't pay close attention to the connection of the two wires from the terminals of the mercury switch. I have everything else wired back up.

I'm pretty sure one attaches to the top terminal. Where does the other connect? Middle or bottom terminal?

Thank you in advance.

Pilot Assembly.jpg


Full Time RVer
Staff member
Dec 2, 2008
Wherever we're parked
Any switch connected to a millivolt type has valve should be connected to the TH & TH-TP labelled terminals. TH = THermostat (which is a switch). TP = ThermoPile.
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