The following service procedure provides a quick overview for
L7224 Series Controllers. For more information, refer to form
On the L7224U the High Limit, High Limit Differential, Low Limit,
and Low Limit Differential can be adjusted to the settings
recommended by the boiler OEM.
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
simultaneously for three seconds. Press the I button until the
feature requiring adjustment is displayed:
Ldf—Low Limit differential.
F - C—°F or °C.
Then press the UP and/or DOWN buttons to move the set point to
the desired value. After 60 seconds without any button inputs, the
control will automatically return to the READ mode.
To use the L7224U in a cold start boiler application, disable the
Low Limit function by pressing the UP arrow button, DOWN arrow
button and I buttons simultaneously for three seconds. Then push
the I button until LL is displayed. Then press the down arrow
button until OFF is displayed.
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 (HL) High Limit is displayed,
followed by a three-digit number, i.e., 220, followed by °F or °C.
TECHNICIAN'S QUICK REFERENCE GUIDE