Gas Furnace Pressure Switch

The switch is there to prevent the furnace from running unless the correct venting air pressure is present.

Gas furnace pressure switch.

By this point on an 80 efficiency furnace if you haven t found the culprit you will have to put on your best thinking cap because the issue could be any number of things including a bad board loose or bad wire connections or a bad pressure switch. A gas furnace pressure switch closes to allow current to pass through and start the ignition of the furnace. Ensure the draft is above the required pressure. A furnace pressure switch is a safety device located near the draft inducer motor of a gas forced air furnace.

The pressure switch has a pressure at which it closes which is typically negative. Types of pressure switches the design and number of pressure switches your furnace has depends on whether it uses conventional or condensing technology. A pressure switch is designed to sense the negative pressure created by the draft inducer motor during the furnace startup and. Onetrip parts furnace pressure switch high temp tubing 3 16 i d.

Example gas furnace pressure switch on amazon lefoo lf31 air furnace differential heating ventilation pressure switch 100pa before changing out an inducer motor or pressure switch keep in mind that a kinked hose clogged flue pipe or anything that stops the inducer motor from pushing air out the vent will cause a good pressure switch not to work. The pressure switch also guards against gas leaks and prevents the furnace from cycling if there s a mechanical failure. If is in the closed position the furnace stops the sequence and goes into lockout mode until the switch is open. Pressure switches are used to stop the furnace from operating in an unsafe condition.

If the pressure switch is stuck it does not send enough power to the inducer and therefore the ignition sequence does not begin. Here is a quick breakdown of the steps involved in replacing a gas furnace pressure switch once you have sourced your new part. The gas valve will not open if the pressure switch doesn t work so the click sound of the gas valve opening tells us that the pressure switch is fine and the igniter is likely our problem since we should also notice it didn t try and light just prior to the click we heard.