Raypak Xfiire 300B Installation And Operation Manual page 20

Mode 3
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 heater loop (with
priority). See Figure 21.
The system temperature is controlled by the Supply Sensor
(S3) whenever the indirect call for heat is not active. The
DHW Supply Sensor (S5) determines the indirect call/tank
setpoint. During an indirect call for heat the heater firing
rate is determined by the water temperature at the Indirect
Supply Sensor (S6) and the Target Max setting when using
the Indirect DHW sensor (S5).
The Heater/Injection Pump (P1) runs during all heat calls
regardless of priority. The Indirect DHW Pump (P3) runs
during an indirect call for heat with no "Off" delay.
MODBUS
ENABLE
0-10/4-20mA
Figure 21. Mode 3 - Single Heater with Indirect on Heater Loop Primary/Secondary Piping
(MASTER)
VERSA
MODBUS
ENABLE
0-10/4-20mA
PIM
S4a
P1a
S1a
A
= FACTORY INSTALLED SENSOR
= FIELD INSTALLED SENSOR
Figure 22. Mode 3 - Heater Cascade with Indirect on Heater Loop Primary/Secondary Piping
20
VERSA
PIM
P3
S4
P1
S1 S2
VERSA
PIM
P1b
S1b S1c
S2a S2b
B
The Heater/Injection 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 warm weather shut down (WWSD)
temperature setting (if utilized) unless an indirect call for
heat is present.
NOTE: A Tank Aquastat can be used in lieu of the Indirect
DHW Sensor (S5). See VERSA IC Manual (5000.72) for
additional details.
NOTE: See VERSA IC Manual (5000.72) for more
information on cascade systems.
AQUASTAT
LOCATED IN
OUTLET PIPE
S5
S6
P2
S3
1
VERSA VERSA
PIM PIM
P1c P1d
S1d
S2c S2d
C D
FACTORY INSTALLED SENSOR
FIELD INSTALLED SENSOR
Maximum distance not to exceed
1
4 pipe diameters or 12" (305 mm)
AQUASTAT
LOCATED IN
OUTLET PIPE
S6a
P3a
1
CONNECT SYSTEM
PUMP IN PARALLEL
FROM EACH CASCADE
FOLLOWER OUTPUT
P2a
S3a
1
F10629
Maximum distance not to exceed
1
4 pipe diameters or 12" (305 mm)
S5a