Specifications

26
JOHNSON CONTROLS
Form 201.28-NM1.EN.PED/CE (0211)
INSTALLATION
PIPEWORK ARRANGEMENT
The following is a suggested piping arrangement for
single unit installations. For multiple unit installations,
each unit should be piped as shown below.
FIGURE 6 - PIPEWORK ARRANGEMENT
LD15151
-Isolating Valve - Normally Open
-Isolating Valve - Normally Closed
-Flow Regulating Valve
-Flow Measurement Device
-Strainer
-Pressure Tapping
-Flow Switch
-Flanged Connection
-Pipework
MINIMUM WATER VOLUME
It is good practice to include as much water volume
as possible in a chilled water loop. This increases the
thermal mass and “Flywheel” effect within the system
(i.e. the more; the better) which in turn promotes stable
water temperature control and increases reliability by
reducing compressor cycling.
For air conditioning applications, a minimum of 3
gallons/ton is required. It is preferred that the gallon/ton
ratio be within the 5 to 8 range. For process applications,
a minimum of 6 gallons/ton ratio is required with
preference towards a range of 7 to 11. Install a tank or
increase pipe sizes to provide sufficient water volume.
LEAVING WATER TEMPERATURE OUT OF
RANGE
The YVAA chiller line has a maximum leaving
water temperature of 15.6°C (60°F). Where process
applications require a chilled water temperature higher
than what the chiller provides, a simple piping change
can remove the problem. By using a mixture of chiller-
cooled water and returning process water, the chilled
water entering the process can be held at the desired
temperature. A tank can also be used to meet high
leaving water temperature requirements.
FIGURE 7 - LEAVING WATER TEMPERATURE OUT
OF RANGE SUGGESTED LAYOUT
LD15049
RECIRCULATION
SUPPLY TO LOAD
RETURN FROM LOAD
LOAD
FLOW RATE OUT OF RANGE
Each YVAA evaporator has a minimum and maximum
flow rate. Some process applications require a flow
rate that is out of range for the evaporator. In those
applications, a piping change can remove the problem.
In applications where the required flow rate is less than
the evaporator’s minimum allowable, the chilled water
can be recirculated to the chiller.
FIGURE 8 - SUGGESTED LAYOUT FOR
APPLICATIONS WITH A FLOW RATE
LESS THAN THE EVAPORATOR
MINIMUM ALLOWABLE FLOW RATE
LD15049
LOAD
SUPPLY TO LOAD
BYPASS
RETURN FROM LOAD
In applications where the required flow rate is greater
than the evaporator’s maximum allowable, the chilled
water can be recirculated to the load.