26
3.13.3. Wiring the Indirect Sensor
1. An indirect sensor connection is not required if an
indirect water heater is not used in the installation.
2. When the Indirect DHW call for heat is active, the
PIM communicates this to the VERSA. The VERSA
calculates the optimal operation and sends the
firing rate and pump output requests to the PIM so
it can activate the Indirect DHW pump and Boiler
pumps as needed. If an optional Indirect DHW
sensor is connected, the PIM will pass this signal
to the VERSA. This allows the VERSA to optimize
the Indirect DHW demand to maintain the Indirect
DHW setpoint. The Indirect DHW thermostat switch
closure is still required when using the Indirect
DHW sensor. If a VERSA is not present the PIM
shall activate the Indirect DHW pump whenever
the Indirect DHW call is active. The Boiler pump will
also be activated based on the Indirect DHW piping
configuration setting. Consult the VERSA IC manual
(5000.72) for additional configurations.
3. Connect the indirect tank sensor to the terminals
marked INDIRECT DHW SENSOR. See the wiring
diagram on
page 47
. Caution should be used
to ensure neither of these terminals becomes
connected to ground. When using an indirect DHW
sensor to control tank temperature, contact closure
is required across the indirect override connections
for proper operation.
NOTE:
Alternately, a thermostat contact closure can be
used in lieu of the sensor for indirect operation. Connect
the thermostat to the terminals (10 and 12) marked
INDIRECT DHW OVERRIDE.
A
A
CAUTION:
Sensor and control wiring must NOT be run
in chases with line voltage.
A
A
CAUTION:
To prevent an over-temperature condition
from occurring in the indirect DHW system during “limp-
along” operation, set PIM operator dial to be equal to DHW
Target temperature. See VERSA IC manual (5000.72) for
more information on "limp-along" operation.
3.13.4. Wiring the Optional 0–10 Volt
Building Control Signal
1. A signal from an energy management system may be
connected to the boiler. This signal should be a 0-10
volt positive DC signal. The energy management
system can be used to control either the setpoint
temperature of a single boiler or a cascade of up to 4
boilers, or the firing rate of a single boiler.
2. To enable this remote control function, set DIP
switch 5 to the UP position on the PIM. DIP switch
5 Toggles between an EMS (UP) signal or a demand
signal from the VERSA (DOWN).
3. DIP switch 2 on the PIM toggles between a Direct
Drive (UP) input and a Target Temperature (DOWN)
setpoint.
4. For a 4-20mA application, refer to the VERSA IC
manual (5000.72).
5. Connect an Energy Management system or other
auxiliary control signal to the terminals marked
0-10V (+/-) on the field wiring terminals. See
Figure
29.
Caution should be used to ensure that the +0-
10V connection does not create a short to ground.
6. Contact closure across the Enable/Disable
connection is required for boiler operation in this
configuration.
A
A
CAUTION:
Ensure that the +0-10V connection does
not create a short to ground. +0-10V signal is polarity
sensitivity and must not be reversed. +0-10VDC signal
must not exceed 10VDC.
3.13.5. Wiring the Cascade System -
Communication Bus
NOTE:
Use unshielded 18 gauge stranded copper wire for
proper operation.
1. Designate the primary heater as the master heater/
heater1 by leaving DIP switch 2 on the VERSA in
the ON position. All other VERSA controls require
DIP switch 2 to be toggled OFF, designating them
as followers. Follower VERSA boards are ignored
by their corresponding PIM modules. Use standard
18 AWG wire to connect the master VERSA to the
PIM on the followers. A total of 3 followers can be
connected to the VERSA on the master. For systems
requiring more than 4 connected heaters, an external
sequencer such as the Raypak Temp-Tracker Mod+
Hybrid can be used.
2. It is recommended that the shortest length cascade
wiring possible be used to reach between the
heaters. Do not run unprotected cascade wiring
across the floor or where they will become wet or
damaged. Do not run cascade wiring parallel with, or
close to or against, high voltage (120 volt or greater)
wiring. Raypak recommends that the total maximum
length of each set of cascade wiring not exceed
200' (61 m).
3. Connect the FT_BUS wires to the PIM by pressing
down on the slots with a small screwdriver and then
inserting the wires into the holes. See
Figure 30.
Fault will occur if wires are reversed.
