Your gas furnace comes equipped with a number of safety switches to ensure smooth and safe operation. One of these safety switches is known as the draft pressure switch. Correct internal air pressure is critical to the proper operation of your heating system, and this switch helps your system to know whether or not the right level of air pressure is present for operation. As with any component in your heating system, the draft pressure switch can malfunction. If you are experiencing issues with your system, don’t try to determine what the problem is yourself. Instead, call the Portland heating experts you can trust: Clean Air Act.
The Draft Pressure Switch
When your heating cycle starts, air is pulled into the combustion chamber via the draft inducer fan. The furnace pressure switch is designed to sense the negative pressure created by the draft inducer fan at start up, and if the air pressures and venting are not correct, the switch will shut down ignition.
Types of Draft Pressure Switches
The design of the draft pressure switch used in your furnace will depend upon the design of your furnace itself.
- Single stage conventional furnace – this type of furnace will have one hose on the pressure switch that leads to the body of the draft inducer fan.
- Single stage condensing furnace – a single stage condensing furnace has two hoses on the pressure switch: one for sensing the pressure at the draft inducer fan and a second one for sensing the pressure at the condensate collector box.
- Two stage furnace – a two stage furnace can have two pressure switches as there are two heat exchangers, so each exchanger will have its own switch.
Common Problems with a Draft Pressure Switch
Pressure switches operate at 24 volts, so if the electrical flow to the switch is below that, the switch won’t work. Another common problem with draft pressure switches is that they can become stuck in an “open” position, which will shut down the ignition process every time your furnace starts up.
Draft pressure switches are important safety controls, and are delicate components to work on; this is why it’s important to call a professional for repair. Having problems with your furnace? Call Clean Air Act today and schedule an appointment heating service in Portland with one of our HVAC experts.