Raypak Xfiire 300B Installation And Operation Manual page 19

Mode 2
This mode selection is for hydronic heating systems with
single or multiple heaters (maximum 4 heaters) in primary/
secondary piping configuration with or without Outdoor Air
Reset (S4) with indirect DHW on the system loop (with or
without priority). The system temperature is controlled by
the System Sensor (S3). The Indirect DHW Sensor (S5)
determines the indirect call/tank setpoint. See Figure 19.
The system temperature is boosted to Target Max when
using the Indirect DHW Sensor (S5) during an indirect call
for heat. Priority mode toggles off the System Pump (P2)
when an indirect call for heat is present. The Heater Pump
(P1) runs during any call for heat. The Indirect DHW Pump
(P3) runs during an indirect call for heat with no "Off" delay.
MODBUS
ENABLE
0-10/4-20mA
S4
Figure 19. Mode 2 - Single Heater with Indirect on System Loop - Primary/Secondary Piping
(MASTER)
MODBUS
VERSA
ENABLE
0-10 VDC
PIM
S4a
M
V1a
S1a
A
= FACTORY INSTALLED SENSOR
= FIELD INSTALLED SENSOR
Figure 20. Mode 2 - Heater Cascade with Indirect on System Loop - Primary/Secondary Piping
VERSA
PIM
P1
S1 S2
VERSA
PIM
M
V1b
S2a S1b S2b S1c
B
The Heater Pump (P1) is delayed "Off" as user-defined in
the Heater menu and the System Pump (P2) is delayed
"Off" in the ADJUST menu. The System Pump (P2)
runs whenever the system is enabled for heating and
the outdoor air temperature is lower than the WWSD
temperature setting (if utilized) unless an indirect call for
heat is present with priority.
NOTE: See VERSA IC Manual (5000.72) for more
information on cascade systems.
AQUASTAT
LOCATED IN
OUTLET PIPE
S5
P3
P2
S3
1
1
VERSA VERSA
PIM PIM
M M
V1c V1d
S2c S1d
C D
1
FACTORY INSTALLED SENSOR
FIELD INSTALLED SENSOR
Maximum distance not to exceed
4 pipe diameters or 12" (305 mm)
CONNECT SYSTEM PUMP
IN PARALLEL FROM EACH
CASCADE FOLLOWER
OUTPUT
AQUASTAT
LOCATED IN
OUTLET PIPE
P3
S2d
S3a
Maximum distance not to exceed
4 pipe diameters or 12" (305 mm)
S5
P2a
F10628
19