This BA20149 air pressure switch is a direct replacement for the Trane SWT02979 (and SWT2979) furnace pressure switch.

It's a two-stage switch, rated at 1.25 and 2.25 inches of water column – which basically means it's designed to monitor the inducer motor's pressure to make sure your furnace is venting safely.

If that switch goes bad, your furnace won't fire up.

And it’s a pretty common failure point on older units.

The switch is built tough – corrosion-resistant housing and heavy-duty internals.

It has two wiring terminals and two hose ports, just like the original.

Installation is straightforward: turn off the power and gas, pull the hoses and wires off the old one, mount the new one, and reconnect.

Just make sure you match the hoses to the right ports – they're labeled clearly.

It takes maybe 15 minutes if you’re handy.

This switch isn't just for furnaces either – you can also use it for air compressors, pumps, hydraulic systems, and other pneumatic controls.

It’s a cost-effective way to keep your system running safely and efficiently.

Whether you're an HVAC tech or a homeowner who likes DIY fixes, this part is reliable, accurate, and gets the job done.