Well-Mounted Aquastat Replacement; Replacement Sensor Installation; Wiring; Operation - Honeywell L7224U Installation Instructions Manual

L7224U OIL ELECTRONIC AQUASTAT

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 com-
pound 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
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 cir-
cuit 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

WARNING
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.
69-1720—03
®
CONTROLLER
BOILER
IMMERSION
SENSOR
WELL
HEAT-CONDUCTIVE COMPOUND
(OPTIONAL)
M22026
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.
T
T 3
2
1
ZR
L1
L2
C2
B2
C1
B1
ZC
Fig. 6. Wiring the Outdoor Reset Module and the
Domestic Hot Water Module.

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.
4
50022037-002
OUTDOOR
RESET 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