Sentry S-120 Installation And Operating Instructions Manual - page 8
NOTE: Settings can be checked
using the TEST/SETTINGS Button.
SETTING THE HIGH LIMIT
The high limit is factory set at 88°C
(190°F). To adjust, turn the HI
TEMP Dial
until the desired
setting is displayed. (Setting
range: 38°C–104°C [100°–220°F])
SETTING THE LOW LIMIT
The low limit is designed to main-
tain temperature in boilers equipped with tankless
coils used for domestic hot water. The low limit is
factory set to OFF. Prior to adjusting, remove the
jumper (not equipped on all units)
. Then turn the
LO TEMP Dial
clockwise until the desired tem-
perature is displayed. For proper operation, the low
temperature limit setting should be at least 6°C (10°)
below the high limit setting. NOTE: For cold start
operation, the low limit must be turned OFF. IMPOR-
TANT: If low limit temperature cannot be set above
60°C (140°F), remove jumper
(Setting range:
OFF or 43°C–93°C [110°-200°F]).
SETTING THE ECONOMY FEATURE
The Economy Feature is factory set for a 1 zone heating system.
To adjust, turn the ECONOMY Dial
until the number dis-
played equals the number of heating zones. Do not include indi-
rect water heaters in the number of heating zones. The
Economy Feature conserves fuel by reducing boiler tempera-
ture (see “How Thermal Targeting Works” below). If the heating
system is unable to supply needed heat to the house, the
ECONOMY Dial should be turned to a lower setting (example: In
a three zone house, turn the dial to 2 or 1). Conversely, if the
boiler provides adequate heat, added fuel savings can be
achieved by selecting a higher setting (example: 4 or 5). If the
heating and indirect water heater signals were not separated
when wiring the control, the Economy Feature should be turned
OFF to insure the boiler supplies adequate temperature to heat
the indirect tank.
ACTIVATING THERMAL PRE-PURGE (OPTIONAL)
NOTE: Activation of this feature is not recommended for boilers
with tankless coils.
Fuel Smart HydroStat has a Thermal Pre-Purge feature to maxi-
mize efficiency. When activated, the control will purge higher
boiler temperatures down to 57°C (135°F) at the start of any
thermostat call and supply the latent energy in the boiler to the
heating zone that is calling. During the purge cycle, the display
will indicate Pur. If the heat is not sufficient to satisfy the thermo-
stat, the control will energize the burner. This feature works with
single- and multi-zone heating systems utilizing circulators or
zone valves. No change in wiring is needed.
To Activate Thermal Pre-Purge
Push and hold the TEST/SETTINGS button for 20 seconds. The
display will read Pur On. To deactivate the feature, push and hold
the button a second time for 20 seconds. The display will read Pur
OFF.
SETTING THE CONTROL
At initial start up, with the Economy Feature active, the control
establishes a 63°C (145°F) target temperature. To test the high
limit shut-off function, the Economy Dial must be turned to
OFF. Once tested, restore the Economy setting. If the heating
demand is high, the target will increase over time to satisfy
the heat load. NOTE: To reduce the potential for condensing,
the control will allow the boiler to heat to 49°C (120°F) prior to
energizing the circulator.
Thermal Targeting technology analyzes thermostat activity
and continually evaluate how much heat the house requires.
When it is very cold outside, the heat demand is high and
the Fuel Smart HydroStat will raise the boiler's Target temper-
ature to provide needed heat to the home. When the outside
temperature is milder, the heat demand is lower. During these
periods, the Fuel Smart HydroStat will lower the boiler's Tar-
get temperature – saving fuel – while continuing to provide
comfort to the house.
SYSTEM START-UP
HOW THERMAL TARGETING WORKS
I. BOILERS EQUIPPED WITH HYDROSTAT CONTROL
SETTING
OFF
Disables economy function. Will allow boiler to fire until hi
limit temp is reached and re fire with a 10° subtractive
differential.
LO
Provides lowest level of fuel savings. Use this setting only
if the house does not stay warm at higher settings.
1
Recommended setting for single zone systems
2
Recommended setting for Two zone systems
3
Recommended setting for Three zone systems
4
Recommended setting for Four zone systems
5
Recommended setting for Five zone systems
HI
Provides highest level of fuel savings
A
B
B
D
C
Dynamic
Display
Water Temperature
and Real Time
Verification of Setting
Adjustments.
Low Temperature
Limit Setting
[OFF or 43
o
C 93
o
C (110
o
200
o
F)]
Factory OFF
High Temperature
Limit Setting
[38
o
C 104
o
C (110
o
220
o
F)]
Indicator Light
(announces heat call)
Jumper
B
Diagnostic LEDs and
Test Button
Di erentials are
automatic and will
vary based on control
settings and boiler
temperature
Economy Dial
(OFF or LO, 1, 2, 3,
4, 5, HI)
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Sentry
8