D – 508 C – 07/02 D – EN pag. 8/36
Flow switch
A water flow switch must be mounted in either the entering or leaving water line to insure adequate water flow
through the evaporator before starting the unit. This will safeguard against slugging the compressors on start-up. It
serves to shut down the unit in the event that water flow is interrupted to protect against evaporator freeze-up.
Whenever the unit is equipped with the heat recovery condensers a water flow switch must be mounted in either
the entering or leaving water line to ensure adequate water flow before switching the unit in “Heat recovery mode”.
It prevents the unit from shutting down due to high condensing pressure.
A flow switch is available from DAIKIN; this is a "paddle" type switch which may be adapted to any pipe size from
5" (127 mm) to 8" (203 mm) nominal.
Certain minimum flow rates are required to close the switch (Table 1).
NOMINAL PIPE
SIZE INCHES (MM)
MINIMUM REQUIRED FLOW
TO ACTIVATE SWITCH –
LITERS PER SECONDS
5 (127)
3.7
6 (152)
5.0
8 (203)
8.8
Table 2 – Operating limits – EWAP-AJYNN
Unit version
Standard
OPRN-OPLN
Max ambient temperature (1)
°C
42 38
Min ambient temperature
°C
+10 (2)
+10 (2)
Max leaving evaporator water temperature
°C
+10 +10
Min leaving evap. water temp. (without glycol)
°C
+4 +4
Min leaving evap. water temp. (with glycol)
°C
-8 -8
Max evaporator
Δ
T
°C
6 6
Min evaporator
Δ
T
°C
4 4
Note:
(1)
Max ambient temperatures are referred to units working at full load. With higher temperatures the chillers will
unload.
(2)
When the air temperature is lower than +10°C you need the fan speed control device (OPFS). It allows the unit to
operate with air temperature down to –10°C. Low ambient operation (OPLA) allows to reach –18°C.
Table 3 – Operating limits – EWAP-AJYNN/A
Unit version
Standard
OPRN-OPLN
Max ambient temperature (1)
°C
46 42
Min ambient temperature
°C
+10 (2)
+10 (2)
Max leaving evaporator water temperature
°C
+10 +10
Min leaving evap. water temp. (without glycol)
°C
+4 +4
Min leaving evap. water temp. (with glycol)
°C
-8 -8
Max evaporator
Δ
T
°C
6 6
Min evaporator
Δ
T
°C
4 4
Note:
(1)
Max ambient temperatures are referred to units working at full load. With higher temperatures the chillers will
unload.
(2)
When the air temperature is lower than +10°C you need the fan speed control device (OPFS). It allows the unit to
operate with air temperature down to –10°C. Low ambient operation (OPLA) allows to reach –18°C.
Flow direction marked on switch
NPT flow switch connection
Tee
Table 1
