Flow Switch; High Gas Pressure Switch; Low Gas Pressure Switch - Lochinvar 151 - 801 Operation Manual

5
Field wiring
Tank thermostat
1. Connect the tank thermostats (isolated contact only) to
the tank thermostat contacts as shown in FIG. 5-3.
Tank sensor
1. By installing a tank sensor, the SMART SYSTEM control
can perform the tank thermostat function. The SMART
SYSTEM control automatically detects the presence of
this sensor and generates a DHW call for heat when
the tank temperature drops below the programmed
differential and finishes the call for heat when the tank
temperature reaches above the programmed offset.
2. The tank sensor TST20015 is the only sensor suitable
for use with the SMART SYSTEM control. Connect the
sensor leads to the Tank Sensor terminals on the Low
Voltage Connection Board (FIG. 5-3).

High gas pressure switch

If a switch is provided to detect excessive gas pressure, remove
the jumper wire from the terminals on the connection board,
and then connect them to its normally closed contacts
(FIG. 5-3).

Low gas pressure switch

1. If a switch is provided to detect low gas pressure, remove
the jumper wire from the terminals on the connection
board and connect them to its normally open contacts
(FIG. 5-3).
2. If both a high and low gas pressure switch are used,
connect their respective contacts in series, and connect
them to the terminals on the connection board (FIG.
5-3).
See Section 4 - Gas Connections for a
NOTICE
detailed explanation regarding high and
low gas pressure switch operation.
26
Outdoor Armor Water Heater

Flow switch

1. A flow switch is used to guarantee flow through the water
heater before allowing it to fire. The flow switch must be
installed at the water heater outlet.
2. Connect these terminals to the normally open contacts on
the flow switch (FIG. 5-3).
Rate output
This output provides a 0 - 10V signal that is proportional to
the firing rate of the water heater. This may be used by a BMS
system to monitor the actual rate of the water heater.
ModBus
When the optional ModBus interface module is installed, the
RS-485 ModBus cable is connected to these terminals. Use
shielded, 2-wire twisted pair cable. If desired, the shield can
be connected to ground by installing a jumper wire between
terminals 1 and 3 on connector X5 on the optional ModBus
interface module.
Water heater Building Management
System (BMS)
1. An external control may be connected to control either the
firing rate or the set point of the water heater. If the external
control uses a set of contacts to enable the water heater,
connect the contacts to the Tank Thermostat terminals.
Otherwise, the SMART SYSTEM control will be enabled by
the 0-10V signal.
2. Make sure the (-) terminal is connected to the (-) or
common output terminal of the external control, and the
(+) terminal is connected to the (+) or 0 - 10 VDC terminal
of the external control. Make sure the (-) voltage is not
below ground.
Installation & Operation Manual