AUX. HEAT
EMER. HEAT
COMP.
COMP.
REV.
1ST STAGE COMP.
2ND STAGE COMP.
Diagram 8: Two-Stage Heat Pump
- 16 - - 17 -
(6) OPTIONAL – WIRE THE EVENT TRIGGERED OUTPUT (ETO)
Terminals NO, COM and NC are the
Normally Open, Common and Normally
Closed outputs, respectively, of a relay
that can be used to control auxiliary
equipment. When the relay is on, a
circuit is complete between NO and
COM; when the relay is off a circuit is
complete between NC and COM. The
relay is programmed to be on or off,
with each of the programming events.
Examples of where this output might
be used include:
• Turn on outdoor ventilation for
programming periods of the day
when the building is occupied and
turn it off when unoccupied.
• Have an electronic air cleaner turn
on and off only when the building is
occupied to reduce maintenance
time/cost.
