38
Configuring Multiple W2W WSHP for
Master/Slave Operation
On installations having multiple Water to Water Source Heat
Pumps serving a common load, the heat pumps may be controlled
as a singular heating or cooling source utilizing the
Multi-unit
Master
Operating Mode.
For these installations, the modules are networked together over
the BACnet MS/TP bus. One of the installed Water to Water
Source Heat Pumps operates as a Master control, with the
remaining modules operating as Slaves. Configured thus, the
number of stages required to meet load conditions are determined
by the Master control. Slave modules will receive the number of
stages required from the Master, and will energize their
compressor outputs appropriately in sequence.
In this fashion, a Multi-unit Master system can provide for up to
eight total stages of control. A Multi-unit Master system will
provide coordinated heat pump operation with the same feature set
and sequences of operation as that provided by a Single Unit
configuration.
In this configuration, an independent leaving load water
temperature safety check at each unit is included to verify that
sufficient load water flow is provided. Should the leaving load
water temperature fall below the configured "Chilled Water
Setpoint" in cooling or the "Hot Water Setpoint" in heating, the
compressor stages for any unit (master or slave) will be reduced as
needed without reducing the system staging requirements.
NOTE: Before configuring the units as a Multi-unit Master
systems, be sure to verify configuration for each slave unit for
standalone operation as a fail-safe. Many individual configuration
parameters that are not required or used during slave operation
such as the chilled water and hot water setpoints are hidden (see
screen captions below for hidden points) once the slave is linked
to a master unit. See Fig. 24-26 for visual representations of con
-
figuration.
W2W MASTER CONFIGURATION PARAMETERS
The following configuration parameters can be accessed in the
following figures. (See Fig. 24-26.) Properties
Control Pro
-
gram
Configuration
Service Configuration
Operation Type
Multi-unit Master (default value is Single/Slave Unit)
Total Controlled Stages
1 - 8 (this variable is the total number of stages of all W2W units
to be linked into one single system)
Control Mode Selection
For two pipe systems Manual Heat or Manual/Cool, four pipe
systems SPT, OAT, or System T1Temp
Refrigerant Circuits
Configure for the correct number of refrigerant circuits in the unit
Compressor Stages
1 - 4 (this variable is how many stages the Master unit is capable
of using) Default value is 2
W2W SLAVE CONFIGURATION
The following configuration parameter can be accessed in the
following table. Properties
Network Points
1.
Total Req Sys Comp Stgs
= bacnet://<device instance of
master>/av:88001.
NOTE: This parameter needs to be configured first because
configuration parameters for steps #3, #5, #6 below are hidden
until the Slave and Master units are linked together through
Total
Req Sys Comp Stgs.
The following configuration parameters can be accessed in the
following table. Properties
Control Program
Configura
-
tion
Service Configuration.
2.
Operation Type
- Single/Slave unit
3.
System Stage # Assigned to Y1
- This value defines when
each slave unit will start its first stage Y1output of control for
system staging.
4.
Compressor Stages
- Total number of compressor stages for
each individual unit.
5.
Stage Number of 2
nd
Compressor -
(Option available when
Compressor Stages
= > 2) - On each unit with
Compressor
Stages
set to 2 or more, will be used to identify which output
stage (if any) will be used to verify feedback of the second
compressor, using the second
stage feedback input. This is
always a one to one relationship unless unloaders are present.
6.
Stage Number of 3
rd
Compressor -
(Option available when
Compressor Stages
= > 3) - On each unit with
Compressor
Stages
set to 3 or more, used to identify which output stage (if
any) will be used to verify feedback of the third compressor,
using the third stage feedback input. This is always a one to
one relationship unless unloaders are present.
Below is an example screen shot of the Service Configuration of a
Slave Unit that has bound to a Master W2W unit. The Slave unit
has 2 stages of compression and will be the third stage in the
system.
Summary of Contents for Aquazone 50PSW025
Page 15: ...15 Fig 9 Unit Size 122 1 Phase Complete C Deluxe D Control Package DWG No 50PSW120000 Rev 3 ...
Page 17: ...17 Fig 11 Unit Sizes 122 1 Phase W2W Open Control Package DWG No 50PSW120001 Rev 4 ...
Page 21: ...21 Fig 15 Unit Size 122 240 420 3 Phase W2W Open Control Package DWG No 50PSW320001 Rev 3 ...
Page 36: ...36 Fig 22 W2W Open Control Board ...
Page 37: ...37 Fig 23 Unit Protection Module UPM Sequence Of Operation ...
