Rheem-Ruud 42-106257-01K Pressure Switch

The Rheem-Ruud 42-106257-01K Pressure Switch Kit is the current OEM furnace air pressure switch (also called a draft pressure switch or vacuum switch) for Rheem and Ruud gas furnaces. Its job is to prove that the inducer motor (combustion blower) is pulling a real draft through the heat exchanger and flue before the ignition sequence is allowed to continue. The 42-106257-01K is the replacement for 42-101225-81, which in turn replaced 42-101225-01, 42-101468-01 and 42-101082-01, so a single part number now covers that whole line of earlier switches. This is a single pole single throw (SPST), normally open switch: it sits open with the furnace off and closes only when the inducer pulls enough negative pressure, which completes the 24 VAC safety circuit to the gas valve.

The listed set point for the 42-106257-01K is -0.30 inch water column (WC). The previous 42-101225-81 was published at .35 inch WC, so the trip point is not identical between the old and new numbers. Inside, a flexible diaphragm senses the vacuum through a 1/4-inch barbed port and moves the contacts, and the wiring lands on standard slip-on terminals. Applications include the UGPN series, 80PS models, MXA models, the R801CA, R801PA, R801SA and R801TA series (for example R801CA-075-4-17-MSA). The related 42-106257-01 is the switch listed on its own, while the 42-106257-01K is the kit version of the same number family.

Replacement is simple, but diagnosis comes first. A tripped or failed switch shows up as an inducer motor that runs while the igniter never glows, often with a diagnostic LED flash code for an open pressure switch circuit. Before condemning the switch, check the vacuum hose for cracks, kinks and trapped water, look for a blocked flue, vent termination or heat exchanger restriction, and confirm the inducer wheel is clean and up to speed. A manometer on the hose tells you whether the furnace is actually reaching the set point. Never jumper the switch to force a call for heat; it is a primary safety device, and a bypassed switch can hide a dangerous venting problem.

Key Benefits

• Current OEM Number: The 42-106257-01K is the up-to-date Rheem-Ruud number for the 42-101225-81 pressure switch, so the same part is findable by the new or the old designation.
• Draft Safety Protection: Stays open until the inducer proves -0.30 inch WC of vacuum, which blocks ignition when the flue or heat exchanger is restricted.
• Drop-In Retrofit: Takes the place of 42-101225-01, 42-101468-01, 42-101082-01 and 42-101225-81 with the same 1/4-inch barb hose connection and slip-on wire terminals.
• Genuine Factory Part: Built to Rheem-Ruud specification so the trip point matches what the control board and combustion sequence expect, which cuts down on nuisance lockouts.

Common Questions

• Does the 42-106257-01K replace the 42-101225-81? Yes. The 42-106257-01K is the replacement for 42-101225-81, and that number already covered 42-101225-01, 42-101468-01 and 42-101082-01, so all of them lead to this kit.
• Is the set point different from the old 42-101225-81? The 42-106257-01K is listed at -0.30 inch WC, while 42-101225-81 was published at .35 inch WC. Match the part number to the furnace parts list or rating plate rather than guessing from the old switch alone.
• What does a failing pressure switch look like? The inducer motor runs but the igniter does not glow, usually with a pressure switch open flash code. Check the hose, flue and inducer first, then test whether the switch closes under vacuum.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.