Honeywell L7224U Installation Instructions Manual
69-1720-03
L7224U
Oil Electronic Aquastat
APPLICATION
The EnviraCOM ™ enabled L7224U Oil Electronic
®
Aquastat
sensing in a UL limit-rated controller with a single
sensing probe. The L7224U controls the circulator, oil
burner and boiler temperature.
The L7224U is “Outdoor Temperature Reset” ready,
which is enabled when connected to the 50022037-002
Outdoor Reset Module. (option 1)
Additionally, the L7224U provides adjustable short cycle.
The L7224U replaces the L8124A, L8124C, L7124U,
L7148A, L7248A,C, L7224A,C, and L8148A Controllers.
The Aquastat Controller is intended for use in residentialtype applications.
The L7224U provides status and diagnostic information
through an LED display combined with LED lights as well
as EnviraCOM enabled thermostats and diagnostic tools
to enhance the diagnostic process.
Controller provides electronic temperature
Accessories (Ordered Separately):
50022037-002 AquaReset™ Outdoor Reset Module
C7089U1006 Outdoor Temperature Sensor (used with
the 50022037-002)
W8735S1000 (AquaReset™ Outdoor Reset Kit) includes
50022037-002 and C7089U1006)
50022037-005 Domestic Hot Water Module
32003971-003 Temperature Sensor (used with
50022037-005)
W8735S1008 AquaReset™ Domestic Hot Water Kit
(includes 50022037-005 and 32003971-003)
Sensor (See Table 2).
Sensor Well Clamp 121371AA.
14,000,485-016 1/4 in. (6.35 mm) diameter, 1-1/4 in.
(31.75 mm) length glass cartridge Fuse, 1 A,
Slow-Blow.
120650 Heat Conductive Compound.
Number
123869A 1/2 (12.7) NPT 3 (76.2) 1-1/2 (38.1)
123870A 3/4 (19.05) NPT 3 (76.2) 1-1/2 (38.1)
®
Controller
INSTALLATION INSTRUCTIONS
Table 1. Wells for L7224U Controller.
Part
Spud Size
in. (mm)
Insertion
in. (mm)
Insulation
in. (mm)
SPECIFICATIONS
Electrical Ratings:
Voltage: 120 Vac, 60 Hz.
Power: 7 VA maximum at 120 Vac plus external loads.
Thermostat current: 100 mA nominal at 24 Vac.
Burner Relay:
7.4 A at 120 Vac Full Load Amperage (FLA);
44.4 A inrush Locked Rotor Amperage (LRA);
Less Ignition Load: 360 VA.
Circulator Relay:
7.4 A at 120 Vac FLA; 44.4 A inrush LRA.
Zone Controller (ZC): 7.4 A at 120 Vac FLA;
44.4 A inrush LRA.
NOTE: All loads combined cannot exceed 2000 VA.
Environmental Ratings:
Temperature: -30° F to +150° F (-34° C to +66° C).
Humidity: 0 to 95% relative humidity, noncondensing.
Approvals:
Underwriters Laboratories Inc. Component Recognized.
Canadian Underwriters Laboratories Inc. Component
Recognized.
Table 2. Sensors for L7224U Controller.
Part Number
50001464-001 12 (304.8) Well-mounted controls
50001464-002 18 (457.2) Flush-mounted controls
50001464-003 24 (609.6)
50001464-004 36 (914.4)
50001464-005 48 (1219.2)
Length in.
(mm) Application
L7224U OIL ELECTRONIC AQUASTAT® CONTROLLER
WARNING
INSTALLATION
When Installing this Product...
1. Read these instructions carefully. Failure to follow
them could damage the product or cause a hazardous condition.
2. Check the ratings given in the instructions and on
the product to make sure the product is suitable for
your application.
3. The installer must be a trained, experienced service
technician.
4. After installation is complete, check out product
operation as provided in these instructions.
5. Set High Limit, Low Limit and Differential to the settings recommended by the boiler OEM.
6. Record the maximum High Limit setting from the
replaced controller in the text box provided on the
cover insert label.
7. Record the High Limit setting at the time of installation in the text box provided on the cover insert
label.
3/4
(75)
7-1/8
(181)
Electrical Shock Hazard.
Can cause severe injury, death or property
damage.
Disconnect power supply before beginning
installation to prevent electrical shock or
equipment damage.
Mounting
The L7224U can be mounted in a well mount, horizontal
or vertical position, or flush mounted remote from the well.
IMPORTANT
Immersion well must fit sensing element and
sensor must rest against bottom of well.
New Installation
Order well assemblies separately; refer to Table 1 and
form no. 68-0040, Immersion Wells and Compression
Fittings for Temperature Controllers. Boilers usually have
tappings that allow the well to be mounted horizontally so
boiler water of average temperature can circulate freely
over the well. See Fig. 1 for mounting dimensions.
6-1/2
(166)
5-11/16
(145)
3/8
(10)
2-5/8 (67)
4-1/4 (109)
3-13/32 (86)
2x 1/4 (7) x 3/8 (9)
Fig. 1. L7224U mounting dimensions in inches (mm).
1. Turn off all power and drain the boiler.
2. If no tapping is provided, prepare properly sized and
threaded tapping near the top of the boiler.
3. Sparingly coat the well threads with pipe dope.
NOTE: Do not attempt to tighten by using the case as a
handle.
69-1720—03 2
3-1/32
(77)
1-3/16
(30)
1-1/8 (29)
1/16 (2)
4. Install the well in the boiler tapping and tighten
securely.
5. Refill boiler and check for water leakage.
6. Identify if installation requires vertical or horizontal
mounting.
7. Remove the well knockout, for either vertical or
horizontal mounting, by carefully prying the
knockout from the back of the case, using a
flat-bladed screw driver. Refer to Fig. 2.
2-1/16 (53)
M22147B
KNOCKOUT FOR
HORIZONTAL
MOUNT
SCREWDRIVER
KNOCKOUT FOR
VERTICAL MOUNT
M22118
Fig. 2. Removing horizontal or vertical mounting
8. Loosen but do not remove the well clamp screw.
9. Fit the case into the well so the clamp on the case
slides over the flange on the well.
10. Securely tighten the clamp screw.
11. Insert the sensor element into the well until it
bottoms. (If necessary, slightly bend the wire inside
the case to hold the sensor against the bottom of
the well.)
12. Tur n powe r O N.
13. Set High Limit, Low Limit and Differentials to the
settings recommended by the boiler OEM. (See
OPERATION section, also refer to INSTALLATION
steps 6 and 7.)
IMPORTANT
Best thermal response is obtained with a well
that snugly fits the sensor. Insert the sensor until
it rests against the bottom of the well. Use a well
of correct length and bend the wiring, if necessary, to hold the bulb against the bottom of the
well.
If the well is not a snug fit on the sensor, use the
heat-conductive compound (furnished with
TRADELINE® models) as follows: Fold the
plastic bag of compound lengthwise and twist it
gently. Then snip off end of bag and work the
open end of the bag all the way into the well.
Slowly pull out the bag while squeezing it firmly
to distribute compound evenly in the well. Bend
the wiring, if necessary, to hold the sensor
against the bottom of the well and to hold outer
end of the sensor in firm contact with the side of
the well. See Fig. 3. Wipe excess compound
from the outer end of the well.
knockout.
L7224U OIL ELECTRONIC AQUASTAT® CONTROLLER
SENSOR WIRES
CONTROLLER CASE
IMMERSION
WELL CLAMP
IMMERSION WELL
CLAMP SCREW
BOILER
IMMERSION
WELL
HEAT-CONDUCTIVE COMPOUND
(OPTIONAL)
SENSOR
M16120
Fig. 3. Position of sensor in immersion well.
Flush-Mounted Aquastat Replacement
Turn off all power and remove the old controller. Refer to
the cover insert of the old controller to identify and tag
each external lead as it is disconnected. If the old well is
unsuitable for the new installation, remove it and replace it
with a suitable new well. If the old well is suitable, use it.
See Fig. 1 and 4 for mounting tab location.
THERMOSTAT
TERMINALS
T
T3
2
1
TX
TT
ZR
L1
L2
C2
B2
C1
B1
ZC
FLUSH MOUNTING TAB (2)
Fig. 4. Location of L7224U flush-mounting tabs and
LINE
B1 ZC C1
LEDs.
ENVIRACOM
TERMINALS
TM
DISPLAY
LED's
CAPACITOR
SENSOR
CONNECTOR
RELAYS
TRANSFORMER
SENSOR HOLES
FUSE
RELAY
M22119A
3 69-1720—03
L7224U OIL ELECTRONIC AQUASTAT® CONTROLLER
WARNING
Well-Mounted Aquastat Replacement
Turn off all power and remove the old controller. Refer to
the cover insert of the old controller to identify and tag
each external lead as it is disconnected. If the old well is
unsuitable for the new installation, remove it and proceed
with instructions for new installation. If the old well is
suitable, use it.
1. Loosen, but do not remove, the well clamp screw on
the side of the controller case.
2. Position immersion well clamp snugly over the
flange of the adapter and tighten the clamp screw.
3. Insert the sensor into the well as shown in Fig. 5.
(If desired, distribute the heat-conductive compound in the tube prior to sensor insertion, as
described in New Installation.)
4. Make sure sensor is fully seated to bottom of well
(Fig. 5). Use a small pencil to measure depth of
sensor in well, if necessary.
SENSOR WIRES
BOILER
IMMERSION
WELL
HEAT-CONDUCTIVE COMPOUND
(OPTIONAL)
SENSOR
M22026
Fig. 5. Replacement sensor installation.
Replacement Sensor Installation
Turn off all power and carefully disconnect sensor from
circuit board by pulling gently on the connector.
1. Gently pull sensor from thermo well and through circuit board by pulling on leadwires.
2. Carefully align replacement sensor with hole in
circuit board and guide through Aquastat case and
into well. Refer to Fig. 5.
3. Make sure sensor is fully seated to bottom of well
(see Fig. 5). Use a small pencil to measure depth of
sensor in well, if necessary.
4. Connect sensor to circuit board by pressing
connector on sensor unit into mating connector on
circuit board (refer to Fig. 6).
5. For remote sensors (flush mounted Aquastat) be
sure to use the 121371AA clamp to securely hold
sensor in place. See Accessories.
WIRING
Electrical Shock Hazard.
Can cause serious injury or death.
Disconnect power supply before making wiring
connections to prevent electrical shock or
equipment damage.
All wiring must comply with local electrical codes and
ordinances. Do not exceed the specifications in the
Application section when wiring this controller.
IMPORTANT
The terminals on these Aquastat Controllers are
approved for use with copper wire only.
Follow the appropriate wiring diagrams shown on the
inside of the front cover of the L7224U or in Fig. 9, 10, and
11.
Refer to Fig. 6 for Connections for the optional Outdoor
Reset Module and the Domestic Hot Water (DHW)
module. In subsequent wiring diagrams these modules
will be displayed with a dotted line signifying that they are
optional.
50022037-002
OUTDOOR
RESET MODULE
T
3
T
2
1
ZR
L1
L2
C2
B2
C1
B1
ZC
LINE
Fig. 6. Wiring the Outdoor Reset Module and the
Domestic Hot Water Module.
1 2 3 OT OT
C7089U1006
OUTDOOR
SENSOR
50022037-005
DOMESTIC HOT
WATER MODULE
1 2 3 TS TS
32003971-003
TEMPERATURE
SENSOR
M29651
OPERATION
General
The L7224U Oil Electronic Aquastat Controller is a
primary safety limit-rated device designed for use with oil
fired boilers with line voltage burners and circulators.
Many boilers do not include wiring or controller
compartments as part of the design, but are provided with
an integral, replaceable, immersion well that is the
mounting hardware for the Aquastat Controllers. Wiring to
the other controllers is done through flexible metal
conduit.
For boilers that do include a remotely (flush) mounted
controller, the wiring may be completed with conduit or
routed behind the boiler sheet metal.
A separate electromechanical High Limit is not required in
a system that uses this controller to meet Underwriters
Laboratories Inc. requirements for oil-fired boiler
assemblies, UL 726.
On the L7224U, the High Limit, High Limit Differential,
Low Limit, and Low Limit Differential and Anti-Short Cycle
time can be adjusted to the setting recommended by the
boiler OEM.
69-1720—03 4
L7224U OIL ELECTRONIC AQUASTAT® CONTROLLER
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.
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 range of the Anti-Short Cycle time is from 10
seconds to five minutes.
If a 50022037-002 “Outdoor Reset Module” is installed,
the reset curve can be set by entering the minimum
outdoor temperature, minimum (water or 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°C
to 21°C) and has a default setting of 40°F (4.4°C). The
range of the minimum (water or boiler) temperature is
from 80°F to 180°F (27°C to 82°C) and has a default
setting of 130°F (54°C). 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 L7224U is designed for use with 24 Vac electronic
and electromechanical thermostats and EnviraCOM™
enabled thermostats, and have screw-type terminals for
easy field connection.
To replace a L8148A,C L7148A or L7248A,C controller,
the Low Limit function must be disabled; see Adjusting
Settings for directions.
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. 9) simultaneously
for three seconds. Press the I button until the feature
requiring adjustment is displayed:
• HL_ — High Limit.
• Hdf — High Limit Differential.
• LL_ — Low Limit.
• Ldf — Low Limit Differential.
• duu — ZR input configured as external Domestic Hot
Water (DHW) request (ON/OFF)
• 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)*
• F-C — Temperature units (F or C)
* Settings available for adjustment on the 3-digit display
only if the AquaReset Outdoor Reset Module is installed.
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 controller will automatically return to the
RUN 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 button simultaneously
for three seconds. Then push the I button until LL_ is
displayed. Then press the down arrow button until OFF is
displayed.
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 HL (High
Limit) is displayed, followed by a three-digit number, i.e.,
220, followed by °F or °C. Pressing the I button again will
display the LL (Low Limit) followed by a three-digit
number and the corresponding degree designator. See
Fig. 7 for explanation of display readout.
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 and release any key.
5 69-1720—03
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