5
Primary/Secondary Piping
In primary/secondary applications, the heater outlet
temperature is typically higher than the system loop
temperature. Therefore, the Controller uses an addi-
tional sensor (called the system sensor) to measure
the temperature in the system. The operating sensor in
primary / secondary piping applications is the system
sensor. See Fig. 9.
Modes of Operation (Mode)
The Controller allows for eight modes of operation in
order to define the Controller operation and piping
arrangement used. The piping arrangement can be
categorized into primary or primary/secondary. The
mode of operation is selected using the MODE item in
the adjust menu. The operating sensor measures the
temperature being controlled out to the heating sys-
tem.
The piping arrangement determines which sensor the
Controller uses as the operating sensor. The operating
sensor is either the heater outlet sensor or the system
sensor.
It is up to the designer to determine the necessary
components for and the configuration of the particular
system being designed, including additional equip-
ment, isolation relays (for loads greater than the
Controller’s specified output rating), and any safety
devices which in the judgment of the designer are
appropriate, in order to properly size, configure and
design that system and to ensure compliance with
building and safety code requirements.
Typically, Raypak recommends Mode 2 for
primary/secondary hydronics, Mode 3 for domestic hot
water and Mode 5 for primary/secondary hydronics
using outdoor reset.
NOTE:
Mode of operation MUST be programmed
into the Controller. See Figs. 21 through 25 on the
following pages.
NOTE:
The illustrations for each mode are only
mechanical concept drawings; they are not intended
to describe a complete system, nor any particular
system. Consult the factory for piping arrangements
not depicted here.
RAYPAK TEMPERATURE
CONTOLLER
SYSTEM RETURN
SYSTEM
SUPPLY
ALTERNATE
SENSOR
LOCATION
4 OR MORE
STAGES
SYSTEM SENSOR
MAIN
SYSTEM
PUMP
(BY OTHERS)
OPTIONAL INTEGRAL PUMP
BOIL OUT SENSOR
BOIL IN SENSOR
PUMP LOCATION
ON MODELS WITHOUT
INTEGRAL PUMP
*
*
MAXIMUM 4 TIMES THE PIPE DIAMETER OR 12”, WHICHEVER IS LESS.
Fig. 9: Primary/Secondary Piping (Mode 2)
Two Setpoints Operation, Primary Piping
Mode 1 (MODE = 1)
(Not Supported)
Mode 1 is designed for setpoint operation using
Primary Piping. Once a Call for Heat (CFH) is present,
the control stages the heater to maintain the heater
target 1 at the heater outlet sensor. Once an indirect
DHW override is present, the control stages the heater
to maintain the heater target 2 at the heater outlet sen-
sor. If both demands are present at the same time, the
control operates at the higher of the two targets.
Two Setpoints with Primary/Secondary
Piping
Mode 2 (Mode = 2)
Mode 2 is designed for setpoint operation using
Primary/Secondary piping (see Fig. 9). A CFH is avail-
able to activate a setpoint for space heating. An
indirect DHW override is available to activate a second
setpoint for heating an indirect domestic hot water
tank.
Once a CFH is present, the control stages the heater
to maintain the heater target 1 at the heater supply
sensor. Once an indirect DHW override is present, the
control stages the heater to maintain the heater target
2 at the heater system sensor. If both demands are
present, the control operates at the higher of the two
targets.
Mode 2 requires the use of three water sensors. The
inlet water sensor is located in the inlet side of the
in/out header. The outlet sensor is located in the outlet
side of the in/out header. The system sensor (termi-
nals 6 and 4) must be located as shown in Fig. 9.
