TZ-4 TOTALZONE® ZONE CONTROL PANEL
68-0259-1
16
Thermostat Operation
Conventional Thermostats
Conventional (R,W,Y,G) heat/cool thermostats can be used
with the TZ-4 to control single or multi-stage gas, electric or oil
systems and heat pumps with auxiliary heat.
The panel can be configured to control second stage heat and
cool and third stage heat using a 5-60 minute timer, or staging
can be controlled by the percentage of zones calling.
When using conventional thermostats on heat pump
applications, set DIP switch 5-1 to Off for heat pump
equipment. Set DIP switch 5-7 for correct reversing valve
operation. See Table 7.
Heat Pump Thermostats
HEAT PUMP THERMOSTATS WITH SINGLE Y OUTPUT
Thermostats that have a single Y terminal for first stage heat
and cool and those with separate Y1 and W1 can be used.
Thermostats of either wiring type can be used on any zone.
For thermostats with a single Y, the reversing valve wire must
be connected to O/B:
— Connect the thermostat Y terminal to Y1 on the panel.
— If the thermostat energizes O on a call for cool, connect the
O/B jumper located near the thermostat wiring terminals.
— If the thermostat energizes B on a call for heat, leave the
O/B jumper disconnected.
HEAT PUMP THERMOSTATS WITH SEPARATE Y1 AND W1
TERMINALS
Heat pump thermostats with separate Y1 and W1 terminals for
first stage heat and cool are wired to Y1 and W1/E. Leave the
O/B jumper, located near the thermostat wiring terminals,
disconnected.
Emergency Heat Control
Emergency heat is defined as using an auxiliary heat source
without using the heat pump. When the Em Heat switch is in
the emergency heat position, the heat pump is locked out and
calls for heat are sent to the W1/E equipment terminal for
fixed stage emergency heat. Second stage emergency heat
energizes equipment terminals W3/Aux. Second stage
emergency heat is configured with DIP switch S41 and 2.
When the panel is in the heat pump mode, W1/E is energized
only in emergency heat.
A recommended heat pump thermostat can also control
emergency heat from the thermostat system switch. See
Table 1.
Multi-Stage Thermostats
Use multi-stage thermostats to control up to three stages of
heat and two stages cool with the W1/E,W2, W3/AUX, Y1,
and Y2 thermostat terminals.
Manual and Automatic Changeover Thermostats
Manual or automatic changeover thermostats can be used.
The panel determines the call for heat or cool based on which
was called for first. Subsequent calls for heat or cool are
honored when the initial call is satisfied, or 20 minutes has
elapsed.
Rebooting Microprocessor
To reset the panel, press and release the Boot button.The
system reboots and enters the Purge mode.
Discharge Air Temperature Sensor
The C7735A1000 Discharge Air Temperature Sensor (not
included) is a supply-duct-mounted temperature probe used
to control capacity and prevent high limit or coil-icing. The
sensor attaches to the two DATS terminals on the panel.
When a high or low limit is reached, the panel shuts off the
equipment and keeps the fan operating for 2-1/2 minutes.
After this time, it re-energizes the equipment after the
discharge air recovers by 10 degrees. When the DATS
exceeds the high or low limit, the Heat (red) or Cool (green)
LED flashes.
Set the temperature from 110 °F to 160°F. See Fig. 23. The
recommended setting for fossil fuel/ electric systems is 160°F
(default factory setting). For heat pump systems, the
recommended setting is 120°F. When using a heat pump
with dual fuel activated (DIP 5-8), the high limit will auto-
matically be set for 120 degrees when the outputs call for
compressor only operation. When the outputs call for non-
heat pump operation, the high limit will be set to the adjustable
110° to160°F setting.
The cooling temperature limit can be set at 40°F or 48°F.
Fig. 23. DATS high-limit temperature dial.
IMPORTANT
Be sure the Discharge Air Temperature Sensor wir-
ing does not run parallel with line voltage wiring
unless more than 12 in. of separation exists or
shielded cable is used.
130 F
MAX DUCT
TEMP
M19079A
120 F
110 F
140 F
150 F
160 F