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A separate electromechanical high-limit is not
required in a system that uses this control to meet
Underwriters Laboratories Inc. requirements for oil-
fired boiler assemblies, UL 726.
On the L7224 models, the High Limit, Low Limit, Low
Limit Differential, and Anti Short-Cycle time can be
adjusted to the setting recommended by the boiler
OEM. On the L7248 models, the High Limit, and Anti
Short-Cycle time are also adjustable, see "Adjusting
Settings".
The overall range of the High Limit is from 130 °F to
240 °F (54 °C to 116 °C). Select devices may have
different ranges. Some models have limited ranges on
the High Limit setpoint; this limited range is listed on
the device label.
Some models also have a Low Limit and Low Limit
Differential adjustment. The range of the Low Limit is
from 110 °F to 220 °F (43 °C to 104 °C). Select devices
may have different ranges.
The Zr setting can be set to DHW, Zoning, or for
tankless coil applications depending on the
L7224/L7248.
If an Outdoor Reset Module is installed, the reset
curve can be set by entering the minimum outdoor
temperature, minimum (boiler) temperature, and
maximum outdoor temperature on the 3-digit display.
The range of the minimum outdoor temperature is
from -40 °F to 40 °F (-40 °C to 4.4 °C) and has a
default setting of 0 °F (-18 °C). The range of the
maximum outdoor temperature is from 30 °F to 70 °F
(-1.1 °C to 21.1 °C) and has a default setting of 40 °F.
The range of the minimum (water or boiler)
temperature is from 80 °F to 180 °F (26.7 °C to
82.2 °C) and has a default setting of 130 °F. See the
"Outdoor Reset Module" Installation Instructions
(form number 69-2335) for more information on
setting the boiler reset curve and all related
parameters.
The L7224A,C and L7248A,C,L are designed for use
with 24 Vac electronic and electromechanical
thermostats or EnviraCOM™ enabled thermostats, and
have screw-type terminals for easy field connection.
Adjusting Settings
To discourage unauthorized changing of Aquastat
settings, a procedure to enter the ADJUSTMENT mode
is required. To enter the ADJUSTMENT mode, press
the UP, DOWN, and I buttons (Refer to Fig. 5)
simultaneously for three seconds. Press the I button
until the feature requiring adjustment is displayed:
L7224A,C; L7248A,C,L OIL AND ELECTRIC BOILER
Table 3. Adjustable Features.
Display
HL_
High Limit.
Hdf
High Limit Differential.
LL_
Low Limit. (L7224A, C)
Ldf
Low Limit Differential (L7224A, C)
ELL
External Low Limit (L7248L only)
duu
ZR input configured as external Domestic
Hot Water (DHW) request (ON/OFF)
(L7224A,C/L7248L)
ASC
Anti Short-Cycle Timeout (seconds); "OFF"
is disabled.
otL*
Outdoor Temperature Low (minimum)
parameter for the outdoor reset curve (°F or
°C)
otH*
Outdoor Temperature High (maximum)
parameter for outdoor reset curve (°F or °C)
btL*
Boiler Temperature Low (minimum)
parameter for outdoor reset curve
bP*
Boost Period (minutes). "OFF" is displayed
if Boost is inactive
bS*
Boost step (°F or °C) shown only if Boost is
active (bP=ON)
UUS*
Warm Weather Shutdown Temperature
(°F or °C)
tPL**
Thermal Purging Limit Temperature (°F or
°C), "OFF" if disabled
tPt**
Termal Purging Time Delay (minutes),
shown only if tPL is enabled
PC
Pump Cycling (ON / OFF)
F-C
Temperature units (°F or °C)
* Settings available for adjustment on the 3-digit dis-
play only if a W8735Y1000 or W8735S1000 Outdoor
Reset Kit is installed.
**Settings available for adjustment only when the
W8735Y1000 or W8735S1000 Outdoor Reset Kit is
NOT installed.
Then press the UP and/or DOWN buttons to move the
set point to the desired value, to change between °F
and °C, or to enable (On) or disable (Off) the External
Low Limit. After 60 seconds without any button inputs,
the control will automatically return to the RUN mode.
Display
In the RUN mode, the Aquastat will flash "bt" (boiler
temp) followed by the temperature (i.e., 220), followed
by °F or °C.
To read boiler settings, press the I key to read the
parameter of interest. For example, press I and High
Limit (HL) is displayed, followed by a three-digit
number, i.e., 220, followed by °F or °C. Pressing the I
button again (on L7224 models) will display the Low
Limit (LL) followed by a three-digit number and the
corresponding degree designator. See Display
Readout, Table 4.
After approximately 60 seconds without any key
presses, the display will enter a dim display mode. To
return to the bright display mode, simply press any
key.
5
Definition
68-0281—18
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