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What is the Draft Pressure Switch in a Furnace?

OLYMPUS DIGITAL CAMERABecause furnaces are fuel-burning appliances, they contain a number of different safety mechanisms that monitor the performance of various aspects of your system and shut it down if they detect that something’s wrong. One of those mechanisms, the draft pressure switch, plays a vital role in protecting your home from exposure to dangerous combustion gases. Today we’re going to help familiarize you with the draft pressure switch and how it helps keep your home safe!

 

First, an explanation of the draft inducer fan

 

The draft pressure switch is linked to another one of your furnace’s components: the draft inducer fan. When your furnace begins a heating cycle, the draft inducer fan turns on and draws air through your system’s combustion chamber.

 

The draft inducer fan serves two purposes. First, it ensures that the excess combustion gases that are produced by your furnace are directed toward your system’s ventilation pipes and carried out of your home. Without this fan, those gases could leak into your home’s air and create some serious safety issues.

 

Second, the fan blows soot and dirt out of the combustion chamber so that it doesn’t build up on your furnace’s burners. If that soot were to build up on your burners, it could cause them to burn inefficiently and create further safety problems in your home.

 

What is a draft pressure switch in your furnace?

 

The draft pressure switch is a safety component that monitors the performance of the draft inducer fan and your furnace’s ventilation system. It monitors the pressure inside of the combustion chamber and shuts off the gas to your furnace if the pressure gets too high.

 

If, for example, the draft inducer fan started to malfunction, the draft pressure switch would detect it and shut off the gas supply to your furnace before carbon monoxide could seep out of the combustion chamber. In addition, if your home’s flue pipe were to get blocked by an animal nest, ice or snow, the pressure switch would shut off your furnace and prevent combustion gases from traveling back down the flue and into your home.

 

What happens if the draft pressure switch malfunctions?

 

As with any component of your furnace, the draft pressure switch can sometimes malfunction. Often times, this will cause your furnace shut off right after it begins a heating cycle because the switch can get a bad reading or become stuck. In order to keep your draft pressure switch in good condition, it’s important to schedule a furnace tune-up every year. During your tune-up, we’ll inspect the draft pressure switch and the rest of your furnace’s safety mechanisms to ensure that your system is operating as safe as possible.

 

If you have any questions about a furnace draft pressure switch, or if you’d like a heating system serviced or installed in your home, contact Jerry Kelly, your St. Louis area furnace installation and repair contractor. We provide service all over the St. Louis area, including towns like Dardenne Prairie, Des Peres and Frontenac, MO.

 

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