Technical data

Page 11
UNIT START-UP
Use the procedure below to initiate proper unit start-up:
When the disconnect switch is closed, high voltage is
present in some areas of the electrical panel. Exercise
caution when working with energized equipment.
1. Adjust all valves to their full open position. Turn on
the line power to all heat pump units.
2. Operate each unit in the cooling cycle. Room
temperature should be approximately 70° to 75°F
DB, and 61° to 65°F WB. Loop water temperature
entering the heat pumps should be between 70°F and
110°F.
When the unit is operating in the cooling mode
under ARI conditions, the leaving water temperature
is approximately 10°F warmer than the entering
water temperature at 3 GPM / ton.
Note: Three factors determine the operating limits of
a Horizontal and Vertical unit: (1) return air
temperature, (2) water temperature and (3) ambient
temperature. When any one of these factors is at a
minimum or maximum level, the other two factors
must be at normal levels to ensure proper unit
operation.
a. Turn the unit thermostat to the coolest position. If
the unit has an optional MCO thermostat, set the
selector switch to COOL. Both the fan and
compressor should run.
For heat pumps with an optional ACO
thermostat, adjust the cooling set point to a
temperature at least 3°F below room
temperature.
b. Check for cool air delivery at the unit grille within a
few minutes after the unit has begun to operate. List
the identification number of any machines which do
not function.
c. Check the elevation and cleanliness of the
condensate lines. Dripping may be a sign of a
blocked line.
3. Operate each heat pump in the heating cycle
immediately after checking cooling cycle operation.
A time delay will prevent the compressor from re-
starting for approximately three minutes.
Note: Horizontal and Vertical heat pumps are
designed to start heating at a minimum return air
temperature of 50°F with normal water flow rate and
ambient temperature.
a. If the unit has an optional MCO thermostat, set the
temperature indicator to the highest setting and set
the selector switch to HEAT. The fan and the
compressor should start.
If the unit has an optional ACO thermostat, set the
temperature indicator to the far right setting, and set
the selector switch to AUTO. The fan and the
compressor should start.
b. Once the unit has begun to run, check for warm air
delivery at the unit grille. List the serial number of
any machines which do not function.
4. Establish a permanent operating record by logging
the unit operating conditions at initial start-up for
each unit.
5. If a unit fails to operate, conduct the following
checks:
a. Check the voltage and current. They should comply
with the electrical specifications described on the
unit nameplate.
b. Look for wiring errors. Check for loose terminal
screws where wire connections have been made on
both the line and low-voltage terminal boards.
c. Check for dirty filters. A clogged filter will cause
safety cutouts to stop unit operation.
d. Check the supply and return piping. They must be
properly connected to the inlet and outlet
connections on the unit.
e. Check the fan. If the fan fails to operate, verify the
fan wheel turns freely and is secured to the shaft.
Also verify the fan operates in both heating and
cooling modes.
f. If the checks described above fail to reveal the
problem and the unit still will not operate, contact a
trained service technician to ensure proper diagnosis
and repair of the equipment.
WARNING