Englander Vacuum or Pressure Sensor Switch: CU-VS-AMP Englander

Englander Vacuum Shut-Down Switch Part CU-VS

This sensor needs to see a draw of negative pressure (suction) of at least 0.05″ WC (water column) to close the electrical contacts. The vacuum hose from this switch connects directly to the rear of the stove’s firebox. The controller DOES NOT read any output from this switch and will not throw any specific code if the switch is not working. In all applications where this switch is used, it is connected to the feed circuit to cut power to the auger motor. In stoves that use two auger motors, it is on the upper auger motor circuit.  Most of the stoves that utilize this switch will also have a hopper lid switch that can cut power to the auger motor as well so you may need to troubleshoot both switches. This part was used in 2006 and later model pellet stoves.

2006 and later model pellet stoves use 1 ea CU-VS and 1 ea PU-VS. Pre 2006 models use 2 ea PU-VS.

The Vacuum Shut Down Switches (Part # PU-VS and CU-VS) help control various functions of the unit. If an operational error occurs in the unit, a switch will either stop the top (feed) auger or shut the unit off; if the unit turns off an E-1 Code (error code) will appear in the Heat Range and Blower Speed windows of the Control Board. Situations that could cause this include power failure, Combustion Blower failure, improper flue installation, a blocked flue (from rodents, nests, etc.), or “dirty burning” from burning improper fuel.

NOTE: The “door ajar” vacuum switch port must be kept clean, or the top auger will cease to function. Locate the porthole to the right of the burn pot and, with the stove unplugged and cooled down, use a brush or pipe cleaner (not a vacuum) to keep this port clear of ash or other debris (see picture).