Prestige ACVMax Control Supplement

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7.0 Cascade
7.3 Cascade Installation
7.3.1 System Piping
Standard Cascade installations will utilize a balanced manifold system as
the primary / secondary connection to the system piping as shown in
Figure 21 on page 44 or a reverse return piping arrangement as shown in
Figure 23 on page 46. Split Cascade installations will utilize a balanced
manifold system as the primary / secondary connection to the central heat-
ing loop. Each boiler configured to respond to a domestic hot water call
will also have a direct connection to the indirect water heater as shown in
Figure 25 on page 48. Reference the Prestige Installation and
Maintenance Manual for general boiler installation and piping require-
ments.
7.3.2 System Sensor Installation
Cascade operation requires a System Temperature Sensor to be installed
on the common supply header downstream of all boilers in the system.
Place the System Temperature Sensor within 10’ of the last boiler in the
Cascade System for an accurate temperature reading. Proper placement
and installation of the System Temperature Sensor is critical for reliable
cascade operation. The type of System Temperature Sensor chosen also
greatly affects the accuracy of the system temperature readings.
Three types of System Temperature Sensor are available:
• Direct Immersion - A direct immersion temperature sensor
(MDRKIT05) is the recommended type since it will provide the
most accurate water temperature readings. Install the 1/2” NPT
direct immersion temperature sensor in a tee on the common sup-
ply header downstream of all boilers in the system. Ensure that the
temperature sensor probe is directly in the water flow but not touch-
ing the opposite side of the tee. Wire the sensor to terminals 3 & 4
of X5 on the control module of the Master boiler.
• Dry Well Installation – A temperature sensor (PSRKIT22) installed
in a dry well will measure up to 10°F [5°C] lower than the actual
water temperature. All water setpoints must be lowered at the
Master boiler by 10°F [5°C] from the desired setpoints for reliable
Cascade operation. Install a 3/8”ID drywell in the common supply
header downstream of all boilers in the system. The drywell should
be long enough to be directly in the water flow for the most accu-
rate temperature reading. Insert the temperature sensor into the
well and wire to terminals 3 & 4 of X5 on the control module of the
Master boiler.
• Pipe Mounted Installation – A temperature sensor (PTSENS12)
mounted to the outside of the pipe will measure up to 20°F [11°C]
lower than the actual water temperature. All water setpoints must
be lowered at the Master boiler by 20°F [11°C] from the desired set-
points for reliable Cascade operation. The Pipe Mounted tempera-
ture sensor can be directly strapped to the outside of a 1” to 3”
metallic pipe. Install the temperature sensor as follows:
Fig. 19: System Sensor
Direct Immersion
Fig. 20: System Sensor
Dry Well Installation