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X. Wiring
(continued)
• Outdoor Sensor - Tasseron TSA00AA Outdoor Temperature Sensor (1)
• Outdoor Sensor - Tasseron TSA00AA Outdoor Temperature Sensor (2)
• Header Sensor - Optional Honeywell 32003971-003 (103104-01) Sensor (1)
• Header Sensor - Optional Honeywell 32003971-003 (103104-01) Sensor (2)
• MODBUS - (A)
• MODBUS - (B)
• MODBUS - (-V)
With the exception of the alarm contacts, external power must not be applied to any of the low voltage terminals
- doing so may damage the boiler control. Also note the following:
a. External Limit - The external limit terminals are intended for use with a field supplied safety device, such
as a manual reset high limit. When an external limit is used, the jumper between these two terminals must be
removed. Failure to remove this jumper will render the external safety devices ineffective.
b. Alarm Contacts - These contacts close when the boiler enters a "hard" lockout (lockout requiring manual
reset). They may be used as an input to a building alarm system. Contact rating is 24VAC, 0.63FLA. Do not
use for line voltage applications.
c. EnviraCOM - Used to connect EnviraCOM thermostat or other EnviraCOM device listed by the boiler
manufacturer for use with this boiler. A Honeywell EnviraCOM connection is also located as labeled on the
boiler control itself (Figure 10.5).
d. Outdoor Sensor - Use only the Tasseron TSA00AA (10 KOhms) outdoor sensor supplied with the boiler.
When this sensor is connected and enabled, the boiler will adjust the target supply water temperature
downwards as the outdoor air temperature increases. This sensor should be located on the outside of the
structure in an area where it will sense the average air temperature around the house. Avoid placing
this sensor in areas where it may be covered with ice or snow. In general, locations where the sensor
will pick up direct radiation from the sun should also be avoided. Avoid placing the sensor near potential
sources of electrical noise such as transformers, power lines, and fluorescent lighting. Wire the sensor to
the boiler using 22 gauge or larger wire. As with the sensor itself, the sensor wiring should be routed away
from sources of electrical noise. Where it is impossible to avoid such noise sources, wire the sensor using a
2 conductor, UL Type CM, AWM Style 2092 shielded cable. Connect one end of the shielding on this cable
to ground. See Section XII of this manual for information on enabling the outdoor reset sensor.
e. Header Sensor - When this sensor is installed and enabled, the boiler will attempt to maintain the target
water temperature in the header rather than in the supply. Where the system flow rate varies widely, the use
of a header sensor allows the temperature of the water being sent to the radiation to be more accurately
controlled. Use only the Honeywell 32003971-003 (103104-01) sensor listed above. Locate this sensor
immediately downstream of the second primary-secondary Tee (Figure 10.6). Installation of this sensor in
a well, as opposed to on the surface of the header, is highly recommended. The sensor wiring should be
routed away from sources of electrical noise. Where it is impossible to avoid such noise sources,
wire the sensor using a 2 conductor, UL Type CM, AWM Style 2092, 300Volt 60°C shielded cable. Connect
one end of the shielding on this cable to ground. See Section XII for information on enabling the header
sensor.
f.
MODBUS - Boiler-To-Boiler communication network is used for multiple boiler ("Lead-Lag") installations.
g. 4-20 mA Energy Management System (EMS) - A 4-20 mA EMS may be wired to the controller (Figure
10.4). Manufacturer part numbers for contacts (field supplied) required to install wire leads in JST housing
are:
CAUTION
present in the thermostat or limit circuits. If such a power source is present, it could destroy the boiler's
control. One example of an external power source that could be inadvertently connected to the low
voltage connections is a transformer in the old thermostat wiring.
Do not attempt to use EnviraCOM connections for any purpose not explicitly permitted by the boiler
manufacturer. Attempting to do so may result in unreliable operation and/or damage to controls.
107672-03 - 5/18
• SRSF-61T-250A (Recommended for size 16 AWG wire)
• ASRSFSRSF16K51B (2" lead between contacts)
• ASRSFSRSF16K152B (6" lead between contacts)
• ASRSFSRSF16K305B (12" lead between contacts)
• SRSF-21T-250A (Recommended for size 20 AWG wire)
• ASRSFSRSF20K51B (2" lead between contacts)
• ASRSFSRSF20K152B (6" lead between contacts)
• ASRSFSRSF20K305B (12" lead between contacts)
When making low voltage connections, make sure that no external power source is
85
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