GF-135
Esteem 399 Low NOx Boiler
Chapter 18
OMM-0089_0A
Installation, Operation & Maintenance Manual Controller Operation
Page
148
of
188
AERCO International, Inc.
•
100 Oritani Dr.
•
Blauvelt, NY 10913
OMM-0089_0A
MC1 06/19/14
Ph.: 800-526-0288
18.7.1 Cascade Installation – System Piping
Standard Cascade installations will utilize a balanced manifold system as the primary/secondary
connection to the system piping as shown in Figure 18-47 or a reverse return piping arrangement
as shown in Figure 18-49. Split Cascade installations will utilize a balanced manifold system as
the primary / secondary connection to the central heating 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 18-51.
18.7.2 Cascade Installation – 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. Three types of System Temperature Sensor are available:
a)
Direct Immersion:
A direct immersion temperature sensor (P/N MDRKIT05), as shown in
Figure 18-44a, 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 supply header downstream of all boilers in the system. Ensure that the
temperature sensor probe is directly in the water flow but not touching the opposite side of
the tee. Wire the sensor to terminals15 and 16 of the Master boiler.
NOTE
A direct immersion sensor is recommended for accurate
temperature control.
b)
Dry Well Installation:
A temperature sensor (P/N 69107) installed in a dry well, shown in
Figure 18-44b, 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 accurate temperature reading. Insert the temperature
sensor into the well and wire to terminals 15 and 16 of the Master boiler.
a) Direct Immersion b) Dry Well
Figure 18-44: System Sensor Internal Installation Types
