you should find near-zero resistance between terminals 1 and 2 (normally closed)

Can I use a different pitch if 26 degrees is unavailable

this SPST (Single Pole Single Throw) switch ensures the inducer motor is generating the exact negative pressure required to vent flue gases safely before the ignition sequence begins

Durable Construction: High-quality internal contacts designed to manage interlock switch electrical loads without premature carbon tracking or pitting

you should never replace a longer lead with a shorter one if it creates tension on the connections

Maxitrol TD121 Temperature Selector 30067439-890 you should find near-zero resistanceThe Maxitrol TD121 Temperature Selector is a critical control component designed for Selectra Series 21 and 31 electronic gas modulation systems. Specifically engineered for make up air heating and indirect fired units with atmospheric burners, this remote selector provides precise setpoint management within a 55 90 degrees F range. Unlike standard thermostats, the TD121 functions as a remote setpoint adjuster, communicating directly with the A1010 or