78
Fig 45: PIM
TM
FT_BUS Wire Connection
Cascade Master/Follower Pump and Sensor Wiring
Follow sensor and pump connections for DHW or any of the 3 Modes in Hydronic applications as per
the instructions shown in
beginning on page 70 for the water heater designated as the
MASTER and FOLLOWERS.
The System and DHW pump outputs and any sensor inputs are not used in the Cascade Follower
configuration.
NOTE: where pump control is common across all heaters, eg IDHW, operation of the pump MUST be
provided via a relay box (not supplied). Refer to diagrams in
starting on page 57.
If used, connect the Enable/Disable wiring to terminals
11 and 12
marked
‘Enable/Disable’
on the
Master water heater (Refer to
on page 68). This connection must be provided through dry
contacts closure, which can come from a room thermostat or a remote relay. No power of any kind
should be applied to either of these terminals.
ALARM CONNECTION
An alarm annunciator or light may be connected to the alarm contacts on the water heater at terminals
23 and 24
marked
‘Alarm Dry Contacts’
. The Alarm Contacts are 3A rated dry contacts on a normally-
open relay that close during fault or lockout conditions, and the maximum voltage across the contacts
is 30 VAC or 30 VDC. Refer to
on page 68.
In a cascade system, the alarm output of the Master water heater will be active if either the Master
water heater or any of the Follower(s) have a lockout condition. The alarm output of the Follower water
heaters will only energize if a lockout condition occurs on that specific water heater.
BMS COMMUNICATION
The MVB is equipped as standard with a communications port for connectivity to building automation
via Modbus protocol. Refer to the VERSA IC manual
for further information.
Other protocols such as Lonworks, Metasys and Bacnet may be used with the addition of interface
cards. Refer to Rheem for further information.
