Raypak XTherm 1005A Installation And Operation Manual page 17

Mode 2 (Type H Units Only)
This mode selection is for hydronic heating systems with
single or multiple boilers (Maximum 4 boilers) 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). See Figure 18.
The Indirect DHW sensor (S5) determines the indirect
call/tank setpoint. The system temperature is boosted
to Target Max when using the Indirect DHW sensor (S5)
during an indirect call for heat.
MODBUS
ENABLE
0-10/4-20mA
S4
Mode 3
This mode selection is for hydronic heating systems with
single or multiple boilers (Maximum 4 boilers) in primary/
secondary piping configuration with or without Outdoor
Air Reset (S4) with indirect DHW on the boiler loop (with
priority). See Figure 19.
The system temperature is controlled by the Supply sensor
(S3) whenever the indirect call for heat is not active. The
indirect DHW Supply sensor (S5) determines the indirect
call/tank setpoint. During an indirect call for heat the
boiler 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 Indirect
DHW Pump (P3) runs during an indirect call for heat with
VERSA
PIM
S1 S2
P1
Figure 18. Mode 2 - Single Boiler with Indirect on System Loop
MODBUS
VERSA
ENABLE
PIM
0-10/4-20mA
P3
S4
S1 S2
P1
Figure 19. Mode 3 - Single Boiler with Indirect on Boiler Loop
Priority mode toggles off the System Pump (P2) when an
indirect call for heat is present. The Indirect DHW Pump
(P3) runs during an indirect call for heat with no "off" delay.
The System Pump (P2) delay "off" as user-defined in the
ADJUST menu, and the integral Boiler / Injector pump (P1)
is delayed "off" as user-defined in the BOILER 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.
For pipe sizing, see Table G and Table H.
AQUASTAT LOCATED
IN OUTLET PIPE
S5
P3
P2
S3
FACTORY INSTALLED SENSOR
FIELD INSTALLED SENSOR
1
Not to exceed 4 pipe diameters
1
or 12" (305 mm)
no "off" delay. The System Pump (P2) delay "off" as user-
defined in the ADJUST menu, and the integral Boiler /
Injector pump (P1) is delayed "off" as user-defined in the
BOILER 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.
For piping Sizing, see Table G and Table H.
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
FACTORY INSTALLED SENSOR
FIELD INSTALLED SENSOR
Not to exceed 4 pipe diameters
1
or 12" (305 mm)
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