Domestic Hot Water - Raypak 992C Installation & Operating Instructions Manual

Fig. 19: MODE 2 - Single Boiler with Indirect
on System Loop
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 sys-
tem 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. The system temperature is boosted
to Target Max when using the Indirect DHW sensor
(S5) during an indirect call for heat. Priority mode tog-
gles off the System Pump (P2) when an indirect call for
heat is present. The Boiler Pump (P1) runs during any
call for heat. The Indirect DHW Pump (P3) runs during
an indirect call for heat with no "off" delay. The Boiler
Pump (P1) is delayed "off" as user-defined in the
BOILER menu and System Pump (P2) delay "off" as
user-defined 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 indi-
rect call for heat is present with priority.
Fig. 20: MODE 3 - Single Boiler with Indirect
on Boiler Loop
Mode 3 (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 boiler
loop (with priority). The system temperature is con-
trolled 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 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 Boiler 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. The Boiler Pump (P1)
is delayed "off" as user-defined in the BOILER menu
and System Pump (P2) delay "off" as user-defined 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 tem-
perature 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 the Versa IC manual
for additional details.
*Maximum 4 times the pipe diameter or 12", whichever is less.
Fig. 21: Dual Heaters (Reverse/Return)
with Primary/Secondary Piping

Domestic Hot Water

When designing the water piping system for domestic
hot water applications, water hardness should be con-
sidered. Table H indicates the suggested flow rates for
soft, medium and hard water. Water hardness is ex-
pressed in grains per gallon.
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