Venstar T1900 - Manual (Page 60)

13
Page 13.1
Programming the Thermostat to
Operate a Dual Fuel System
Advanced Setup step #21 (next page) allows this thermostat to be
configured to control two heat sources for Dual Fuel operation.
Dual Fuel systems utilize an outdoor temperature sensor. When the
outdoor temperature is at or below the Changeover Balance Point,
step #22 (next page), the primary heat source is ‘locked out’ and
the heat source connected to W3 is energized. There is a three
degree deadband from the Changeover Balance Point, which
requires the outdoor temperature to rise three degrees before
switching back to the primary heat source. If an outdoor
temperature sensor (RS2) is not installed and the thermostat is
programmed for Dual Fuel operation, 1st and 2nd stage heating is
locked out and only W3 will be energized (see page 13.3 for
detailed information).
For outdoor sensor (RS2) wiring please see page 16.2 of this
manual and for the thermostat jumper setting and wiring
instructions please refer to page 5.6 of the Installation
Instructions.
SECTION 13
Dual Fuel Operation