42-105601-29 – FURNACE PRESSURE SWITCH (-0.20PF)

If your furnace is short-cycling (turning on and off repeatedly), a failed pressure switch may be the cause. This is a Rheem OEM pressure switch at -0.20″ WC that also cross-references to the Carrier HK06WC090 — making it a useful part to stock if you work on both brands.

Specs: -0.20″ WC setpoint, OEM Rheem replacement, cross-references to Carrier HK06WC090

Replaces: 42-105601-29, HK06WC090

Fits: Rheem and Ruud gas furnaces; also cross-references for some Carrier, Bryant, and Payne models

Need help? See our Furnace Short Cycling Guide.

In stock at Open To Public HVAC Parts in Dallas. We test parts at the counter before you buy. Call or text (214) 340-9421.

Specs

• TypeFurnace inducer pressure switch (single-stage)
• Trip Pressure-0.20" WC
• Connector1/4" spade terminals
• ResetAutomatic (closes when pressure returns to normal)
• OEM CompatibilityUniversal

Cross-reference numbers

This part replaces the following OEM and aftermarket numbers:

• HK06WC090
• 42-105601-29

Not sure if your number matches? Call (214) 340-9421 or bring the old part in — bench-testing is free.

Fits these models

• Universal aftermarket furnace pressure switch — direct replacement for inducer draft-proving switches on residential gas furnaces
• Common applications: Rheem RGRA/RGFD/RGLE, Goodman GMS/GMSS, Trane / American Standard XV/XR, Carrier / Bryant Performance/Preferred, York / Coleman TG9S/TM9V, Lennox EL/SL series, Nordyne / Intertherm
• Match the negative pressure rating (-0.20 / -0.27 / -0.30 / -0.35 / -0.40 / -0.47 / -0.50 / -0.60 / -0.70 WC) EXACTLY to your existing switch

My furnace tries to start but never ignites -- is the pressure switch bad?

Maybe. Inducer pressure switches not closing are normally caused by one of four things: a bad switch, a bad inducer motor, a clogged flue vent, or a clogged hose between the switch and the inducer. Check the hose and vent first (free), then bench-test the switch and the inducer.

My furnace lights then shuts off after a few seconds -- could it be the pressure switch?

Almost never. That symptom is virtually always a dirty flame sensor -- the burner lights, but the sensor isn't pulling enough microamps to confirm flame, so the board closes the gas valve as a safety. Clean the flame sensor with fine emery cloth first.

What does -0.40PF mean?

That's the negative pressure rating: 0.40 inches of water column, "PF" indicates the trip direction (some are PR / 'pressure rising'). When inducer draft pulls the diaphragm down by 0.40" WC of vacuum, the switch closes the safety circuit. Match this rating EXACTLY -- wrong rating = nuisance trips OR no protection.

Can I jumper the pressure switch to make the furnace run?

NO. The switch is a safety device. Bypassing it can cause carbon monoxide buildup, vent gas spillage into the house, or fire. If yours is truly bad, replace it.

What's the difference between PF and PR ratings?

PF = pressure-falling, PR = pressure-rising. Some 2-stage furnaces use both styles on the same switch. The trip direction matters for how the board reads the safety circuit -- verify your existing switch's marking before swapping.

How long should a furnace pressure switch last?

10-20 years typical. Most failures come from water intrusion in the hose / port, not switch failure itself. Replace the silicone hose every time you service the inducer.