Pressure switch showing the electric switch
The switch on this side is usually single pole NO
|
Same pressure switch showing tap for pressure line
The pressure tap that senses the negative pressure from the inducer is located at the top.
|
|
|
The pressure switch will not allow the burners to operate if it does not read the proper pressure.
|
Purpose of the pressure switch
The pressure switch is probably the most changed part in the furnace but it does not fail all that often.
It is a control that tells the furnace if the venting and combustion air are flowing at the correct rate. On 80% furnaces it is usually mounted on the inducer housing.
If there is a blockage in the vent, rust in the heat exchanger or perhaps a crack in the heat exchanger, the air flow will be upset.
The pressure switch will block ignition if the conditions are unsafe.
When the pressure switch fails to make, it is best to look closely at the rest of the furnace.
On most furnaces, the pressure switch is an OEM part. It is designed to fit the specific furnace. An adjustable general replacement part will not do.
It is a control that tells the furnace if the venting and combustion air are flowing at the correct rate. On 80% furnaces it is usually mounted on the inducer housing.
If there is a blockage in the vent, rust in the heat exchanger or perhaps a crack in the heat exchanger, the air flow will be upset.
The pressure switch will block ignition if the conditions are unsafe.
When the pressure switch fails to make, it is best to look closely at the rest of the furnace.
On most furnaces, the pressure switch is an OEM part. It is designed to fit the specific furnace. An adjustable general replacement part will not do.
The following video shows how to check the pressure switch and inducer.
Return to 80% furnace design
