User Guide

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b) Outdoor Sensor - Use only the Tasseron TSA00AA outdoor sensor supplied with the boiler. When this sensor is con-
nected 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uorescent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.
c) Lowwatercut-offwiring–Althoughnotnecessarytoprotectthisboiler(seePartIX),somejurisdictionsmayinsistthat
a low water cut-off (LWCO) be installed with this boiler. There are two ways to wire a LWCO into this boiler:
• A 120V LWCO may be wired to break 120V power to the boiler (Figure 10.4a)
• A 24V LWCO may be wired so that its contacts are wired to the external limit connections on the boiler. When
thisisdoneaseparatetransformermustbesuppliedbytheinstallertopowertheLWCO’ssensingcircuit.This
transformer must be completely isolated from the boiler wiring (Fig 10.4b).
CAUTION
 When making low voltage connections, make sure that no external power source is
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.