PS000 – PRESSURE SWITCH

Cleveland Controls field-adjustable air pressure sensing switch kit. It proves draft or combustion-air flow before the control will allow ignition, and it can sense positive, negative or differential pressure. SPDT contacts let it replace either a normally open or a normally closed OEM switch, and interchangeable springs cover a wide set point band. Set it to the exact pressure the equipment maker specifies, or it will not detect a blocked vent.

Specifications published by the manufacturer. Source: manufacturer documentation.

Specs

• ManufacturerCleveland Controls
• TypeField-adjustable air pressure sensing switch kit
• Set point range0.10" w.c. to 10.0" w.c. using the field-selectable springs
• SensingPositive, negative or differential air pressure
• ContactsSPDT
• Contact rating1/10 HP @ 120 to 277 VAC
• Pilot duty28 VA @ 24 VAC; 125 VA @ 120 VAC
• Operating temperature-40 F to 190 F
• Agency listingsUL, cUL, CSA, CE, AGA

Cross-reference numbers

This part replaces the following OEM and aftermarket numbers:

• NS2-0000-04
• NS2-0000-01
• NS2-0000-08

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

What does the furnace pressure switch prove?

It is a normally open switch on a hose running to the inducer housing or the heat exchanger. When the inducer spins up and pulls enough negative pressure, the contacts close and the board is allowed to light the burners. A switch marked -0.75 in. W.C. closes at three quarters of an inch of water column of vacuum. That is the furnace verifying draft before it makes fire.

Mine will not close. Do I need a new switch?

Usually not, because these do not fail all that often. On a 90 percent furnace look at the condensate trap and drain line first - water backing up into the secondary heat exchanger is the most common cause we hear about. After that, the hose (cracked, kinked, or full of crud and water), the port on the inducer housing, the flue and intake for a bird or wasp nest, and the inducer itself for weak amp draw or a chewed up wheel.

How do I pick the right one?

Read the setpoint off the switch body. It is printed or stamped right there, along with whether it is a single or two-stage switch. Do not guess by looks - the same housing gets built at a half dozen different pressures, and -0.75, -0.80 and -0.85 in. W.C. are indistinguishable on the shelf. Bring the old switch or a clear photo of the label.

Can I jump it out to get heat tonight?

No. That switch is what keeps a blocked flue from pushing combustion gas into the house instead of out the roof.