Rheem Raypak MVB 503A Installation And Operation Manual page 16

Applications and Modes
®
The VERSA IC Control system is designed for a wide
range of applications. The installer/design engineer should
refer to the following Modes to determine which best fits
the intended application and functionality for the unit being
installed.
Type H models of MVB have three modes available to them
to address the various applications the units can be applied
to. Type WH units will only have the WH configuration
available to them for use with potable water applications
when directly connected to a hot water storage tank.
Mode 1 (Type H Units Only)
This mode selection is for hydronic heating systems with
single or multiple boilers (consult the VERSA IC
241493 for additional information on Cascade Systems)
in primary/secondary piping configurations (consult the
®
VERSA IC manual 241493 for additional information on
Cascade Systems) Outdoor Air Reset (S4). The system
temperature is controlled by the System sensor (S3). The
Boiler Pump (P1) runs during any call for heat. The System
Pump (P2) runs whenever the system is enabled for
heating and the outdoor air temperature is lower than the
warm weather shut down (WWSD) temperature setting (if
utilized). The Boiler Pump and System Pump are delayed
"off" as user defined in the ADJUST menu. See Figure
12, Figure 13. (Images show 4 boilers for illustration only).
NOTE: MODE 1 can also be used for process heating
applications in conjunction with a buffer/storage tank
when operating temperatures above 160°F are required.
Care must be given to ensure water hardness is no more
than 15 grains per gallon for scale-free operation.
(MASTER)
MODBUS
VERSA
ENABLE
PIM
0-10 VDC / 4-20mA
S4a
P1a
S1a S2a
A
FACTORY INSTALLED SENSOR
FIELD INSTALLED SENSOR
16
®
VERSA
PIM
P1b
S1b S2b
B
MODE 1 CASCADE
A = MASTER
Figure 13. MODE 1 - Boiler Cascade with Primary/ Secondary Piping
NOTE: See VERSA IC ® manual (241493) for additional
details.
MODBUS
ENABLE
0-10 VDC / 4-20mA
S4
S1
manual
FACTORY INSTALLED SENSOR
FIELD INSTALLED SENSOR
Maximum distance 4 system pipe diameters, not to
1
exceed 12" (305 mm)
Figure 12. MODE 1 - Single Boiler with Primary/Secondary
Piping
VERSA
PIM
P1c
S1c S2c S1d
C
B-D = FOLLOWER UNITS
VERSA PIM
P1
S2
MODE 1
VERSA
PIM
CONNECT SYSTEM PUMP
IN PARALLEL FROM EACH
CASCADE FOLLOWER
OUTPUT
P1d
S2d
D
Maximum distance 4 system pipe
1
diameters, not to exceed 12" (305 mm)
P2
S3
1
F10514
P2a
S3a
1
F10515