LP-551 Rev. 3.9.16
32
I. Optional 0-10 Volt Building Control Signal
1. A signal from a building management system may be
connected to the boiler to enable remote control. This signal
should be a 0-10 volt positive-going DC signal. When this input
is enabled using the installer menu, a building control system
can be used to control the set point temperature of the boiler.
The control interprets the 0-10 volt signal as follows; when the
signal is between 0 and 1.5 volts, the boiler will be in standby
mode, not ring. When the signal rises above 1.5 volts, the
boiler will ignite. As the signal continues to rise towards its
maximum of 10 volts, the boiler will increase in set point
temperature. See Part 10 for details on the setting of function
16.
2. Connect a building management system or other auxiliary
control signal to the terminals marked 16, 0-10 VOLT + and
17, 0-10 VOLT – in the electrical junction box (shown in Figure
22). Caution should be used to ensure that the 0-10 VOLT +
connection does not become connected to ground.
3. Move jumper on connection board (shown in Figure 24)
from A to B.
4. See Function 17 this manual to program the 0-10 volt signal.
NOTE: When a 0-10 volt building management system is
installed, the return sensor temperature cannot be monitored
through the appliance display.
J. Optional UL353 Low Water Cut-O Interface Kit
If an optional Low Water Cut-O (LWCO) Kit is used, the
LWCO probe should be mounted into the tting provided in
the outlet combination tting.
Follow the complete instructions included in the kit for proper
installation.
K. Wiring of Cascade System Communication Bus
1. A Cascade Bus Termination Plug has been installed on the
customer connection board of this boiler. The purpose of
this plug is to stabilize communication between multiple
boilers and reduce electrical “noise”. See Figures 23 and 24 for
Cascade Bus Termination Plug installation detail.
2. Use standard CAT3 or CAT5 computer network patch cables
to connect the communication bus between each of the
boilers. These cables are readily available at any oce supply,
computer, electronic, department or discount home supply
store in varying lengths. If you possess the skills you can also
construct custom length cables.
Figure 23 - Cascade Termination Plug Detail
3. It is recommended to use the shortest length cable that will
reach between the boilers and create a neat installation. Do not
run unprotected cables across the oor where they may become
wet or damaged. Avoid running communication cables parallel
and close to or against high voltage (120 volt or greater) wiring.
HTP recommends that the maximum length of communication
bus cables not exceed 200 feet.
4. Route the communication cables through one of the
knockouts in the cabinet.
5. Connect the boilers in a daisy chain conguration as shown
below. It is best to wire the boilers using the shortest wire
runs rather than trying to wire them in the order that they are
addressed. The communication bus jacks on the customer
connection panel are interchangeable so you can use either one
or both in any order to connect the cable.
If you have connected the boilers to each other properly, there
will be no open communication connection ports.
L. Cascade Master Pump and Sensor Wiring
1. Connect the system pump hot wire to the terminal marked 8.
2. Connect the system pump neutral to the 2 terminal and the
pump ground wire to the 3 terminal.
3. Connect a jumper wire from the 120 VOLT terminal to the 9
terminal.
4. Connect the boiler pump to the terminals marked 1 (HOT), 2
(NEUT) and 3 (GND).
5. Connect system pipe sensor to terminals marked 10 and 11.
M. Cascade Follower Pump and Sensor Wiring
1. Connect the boiler pump to the terminals labeled 1 (HOT), 2
(NEUT), and 3 (GND).
2. An alarm bell or light can be connected to the alarm contacts
of the follower boiler. The normally closed alarm contact may be
used to turn a device o if the boiler goes into lockout mode. The
alarm contacts are rated 5 amps at 120 VAC.
To connect an alarm device, connect the power for the device to
the ALARM COM terminal. Connect the alarm device hot wire
to the ALARM NO terminal. Connect the neutral or return of the
alarm device to the neutral or return of the power for the alarm
device.
To connect a device that should be powered o during a boiler
lockout condition, follow the same instructions as above except
use the ALARM NC terminal rather than the ALARM NC terminal.
Note that in a cascade system the alarm output of the boiler
addressed as #1 will also be active if the master boiler has a
lockout condition. The alarm output of boilers addressed as 2-7
will only activate an alarm if a lockout condition occurs on that
specic boiler.
would then be wired into the master boiler terminals on the
low voltage strip as shown on Figure 24.
NOTE: If sensor wires are located in an area with sources of
potential electromagnetic interference (EMI), the sensor
wires should be shielded, or the wires routed in a grounded
metal conduit. If using shielded cable, the shielding should be
connected to the common ground of the boiler.
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