A & T International 1, Service Manual

Page: 16 / 24

16
Choosing a Thermostat
EMI offers several remote thermostats compatible with
air handlers. Choose a thermostat that matches the
equipment you have selected. For single stage cooling or
heating choose single stage Heat/Cool thermostat.
When selecting a thermostat other than those offered
by EMI, choose a 24V thermostat that matches your
application. EMI equipment is compatible with most
mercury bulb, digital or power stealing thermostats.
Cooling Only With Electric Heat Or Hydronic Heat
Select a thermostat compatible with cooling - electric heat
system. Thermostat should have “R”, “Y”, “W” and “G”
terminals. Thermostat may also have “C” terminal.
High-Wall Thermostat Control Start-Up
INFRARED REMOTE CONTROL OPTION
OPERATIONAL RANGE 55- 90° F (IN 1° INCREMENTS.)
Figure 6
1. Dry Mode Button
2. Temp. Set Point UP/DOWN Button
3.Power ON/OFF Button
4. Fan Speed Button (HIGH, LOW, AUTO)
5. Operational Mode Buttons (HEAT, FAN COOL)
NOTE: Batteries Included.
Fan Operation
Some thermostats are equipped with auto/on fan switch.
When this switch is placed in on position indoor fan will
run continuous. When switch is in auto position indoor fan
cycles with call for heating or cooling.
CHOOSING A THERMOSTAT
Fan Purge
Indoor unit is equipped electronic circuit board with purge
feature. After room thermostat has been satisfied, purge
feature allows indoor fan to remain on for additional 60
seconds. This increases efficiency by pulling remaining
energy from unit.
Cooling Operation
Electronic circuit board of indoor unit also has an anti-
short cycle timer (ASCT) feature designed to prevent
short cycling. Once room temperature is satisfied and unit
switches off, ASCT will not allow unit to restart until three-
minute time period has elapsed.
After connecting thermostat to unit place system switch
in cool mode. Adjust set-point temperature below room
temperature. For chilled water systems, coldwater valve
opens allowing flow of water. Place set-point temperature
above room temperature. CW valve closes while indoor fan
remains on for additional sixty seconds.
Electric Heat Operation
Place thermostat system switch in heat mode . Adjust set-
point temperature above room temperature. Electric heat
energizes with the indoor fan motor. Heating continues so
long as set-point remains above room temperature. Place
set-point temperature below room temperature. Electric
heater switches off and indoor fan remains on for additional
sixty seconds.
Hydronic Heat Operation (Optional On CCP Units)
O ptional hydronic heat package may be selected in lieu of
electric heat. Heating operation is essentially same as units
with electric heat. With thermostat system switch set to
heat and set-point temperature above room temperature,
hydronic valve opens allowing water to flow through coil.
Indoor fan switches on and warm air will flow from unit.
Heating will continue so long as set-point remains above
room temperature. Place set-point temperature below
room temperature. Hydronic valve will close and indoor fan
switches off after sixty-second purge time has elapsed.
Units with optional hydronic heat coil or chilled water
coil are also equipped with freeze protection thermostat.
Freeze protection thermostat is designed to protect
hydronic coil or chilled water coil from freeze up due to
abnormally cold fresh air from fresh air system. Should
freeze sensor activate, indoor fan switches off to eliminate
source of cold fresh air. For units with hydronic hot water
valve installed, valve will be energized allowing warm water
to flow and assist in defrost process. System remains in
this state until freeze condition is satisfied where-by freeze
thermostat will reset.
After starting unit, complete Test Unit Performance
Data sheet on page 17.
Save this information for future servicing. In event
there is a problem with the unit.
Perform test again (if possible) and have both sets
of data ready when calling for assistance.