Honeywell L7224A,C, L7248A,C,L Adjusting Settings, Display, Adjustable Features, Definition

L7224A,C; L7248A,C,L OIL ELECTRONIC AQUASTAT® CONTROLLERS

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 a W8735S1000 AquaReset™ 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:

	Table 3. Adjustable Features.
Display	Definition
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 display only if the W8735S1000 AquaReset Outdoor Reset

Module is installed.

**Settings available for adjustment only when the W8735S1000 AquaReset 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 68-0281EFS—05