Expansion Valve Superheat Adjustment (Thermal Expansion Valve); Heating System Startup - Daikin Rebel Applied DPSA Installation And Start-Up Manual

Expansion Valve Superheat Adjustment
(Thermal Expansion Valve)
It is very important that the expansion valve superheat setting
be adjusted to be between 10°F (–12°C) and 14°F (–10°C).
Insufficient superheat will cause liquid refrigerant flood
back to the compressor which may result in slugging.
Excessive superheat will reduce system capacity and shorten
compressor life.
Turn the adjustment stem clockwise to increase superheat.
Not exceeding one turn, adjust the stem and then observe the
superheat. Allow up to 30 minutes for the system to rebalance
at the final superheat setting.
Checking Superheat
Following are recommendations for checking superheat:
1. Close the unit section doors. Operating the unit with its
doors open will affect the expansion valve and system
operation considerably.
2. For units with one expansion valve per circuit, check the
pressure and temperature at the compressor suction
valve.
NOTE: If low oil level is accompanied by heavy foaming
visible in the oil sight glass, it is possible that excess
liquid refrigerant is returning to the compressor.
Check the suction superheat and adjust the
expansion valve for 10°F (–12°C) and 14°F (–10°C) of
superheat. If proper superheat is obtained, sight glass
foaming is not a concern.
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Heating System Startup

General
1. At the keypad, set the heating setpoints high enough so
that the controller calls for heating. Adjust the value in
Main Menu\ Commission Unit\Heating Set-Up\Occ Htg Spt
=
above the Control Temp shown in the same menu. In
addition, on DAC units, adjust the DAT heating value in
Main Menu\Commission Unit\Heating Set-Up\ DAT Htg
Spt above the dischargetemperature shown as Disch
Temp in the same menu.
2. Place the unit into heating mode through the keypad
Main Menu\quick Menu\Ctrl Mode = Heat Only
menu
3. Verify that the high ambient heat lockout temperature
Main Menu\Commission Unit\Heating Setup\
setpoint,
Htg Hi OAT Lk
is set above the current outside air
temperature (OA Temp) is shown in the same menu.
Hot Water and Steam Heat
The Hot Water or Steam valve actuator should open the valve.
The hot water or steam valve is open when the valve stem is
up. If the unit loses power, the spring in the actuator should
drive the valve wide open.
Electric and Gas heat
Electric and gas heaters are addressed later in this manual.
45
Unit Operation
IM 1287 • REBEL APPLIED ROOFTOP
.