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The pressure switch is a small and useful component but can lead to many failures if not understood well. Let’s know what it is and how it works because it’s the pressure switch that might create the biggest of the problems. Focus on the important things first before you change the gas furnace pressure switch.
A furnace pressure switch is a safety component that sends the signal that the inducer motor is working. The inducer motor pulls out toxic gases coming out from the flames. The pressure switch is used as a safety to allow the passage of gas. It acts as a safety mechanism.
First of all, the switch bears a diaphragm. Whenever a vacuum is applied, the diaphragm comes out. The diaphragm doesn’t come out in the absence of a vacuum. A switch is connected to the diaphragm, which tells whether the diaphragm is opened or closed! In the presence of a vacuum, the diaphragm comes out and closes the switch while in its absence, the switch remains open. In such a case, the furnace remains off.
A switch is simply a connection to allow the power to pass. If it is a light switch, pushing the switch on manually will turn on the light, but a pressure switch turns on because of the pressure of air. We can rather say that suction created her turns on the pressure switch.
The inducer fan is responsible for the suction created. Turning on the fan will pull the vacuum present in the switch with the help of the rubber tube. The rubber tube connects the fan and the pressure switch, which is responsible for pulling the switch in to close a circuit. Hence, the power is passed to the igniter.
The main purpose of the switch is to assure that the whole unit is working all right. If there is something wrong with the unit, then it will not work properly. Ultimately, the toxic gases won’t be removed, and there is surely a risk. The best way to know this is that the switch does not allow the unit to ignite until it gets the desired amount of suction.
The various causes for failures due to a furnace pressure switch are:
Keeping a check on the causes of failures can help you out. Following are the ways to resolve in case of a failure:
If you have ruled out that none of these problems are present, then there’s a possibility that the switch is bad. To confirm if the switch is bad, you can apply this method:
A multimeter is used to test the pressure switch and check the continuity of the switch, whether it is closed, or it is opened. The switch is being tested to check if it’s closing when the diaphragm is pulled in. The steps are as follows:
Before you change an inducer motor or decide to change the switch, some other things too must be kept in mind. The other possibilities:
All these possibilities can also stop the gas furnace pressure switch from working well. Make sure you have a look at these things, too, before you finally decide to change the pressure switch. If none of these are present and you have tried all the possible ways to eliminate the causes and check for the faults, it’s time you change the pressure switch and don’t take a risk with it.
Just a random guy who likes to build things. Providing tool knowledge, appliance/device testing tips, and DIY project info in an easy-to read & non-intimidating style.