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IMPORTANT
Immersion well must fit sensing element and
sensor must rest against bottom of well.
New Installation
Order well assemblies separately; see 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.
1. Turn off all power and drain the boiler, if applica-
ble.
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.
4. Install the well in the boiler tapping and tighten
securely.
5. Refill boiler and check for water leakage.
6. Loosen but do not remove the well clamp screw.
7. Fit the case into the well so the clamp on the
case slides over the flange on the well.
8. Securely tighten the clamp screw.
9. Insert the sensor element into the well until it
bottoms. See Replacement Sensor Installation
section for details. (If necessary, slightly bend
the wire inside the case to hold the sensor
against the bottom of the well.)
10. Turn power ON.
11. Set High Limit, Low Limit and Low Limit Differ-
ential to the settings recommended by the boiler
OEM. (See OPERATION section.) (See INSTAL-
LATION steps 6 and 7.)
12. On L7248L models, adjust ELL option to match
your configuration (see OPERATION section,
and Fig. 11 and 13).
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 wir-
ing, 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
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. 2. Wipe
excess compound from the outer end of the
well.
®
models) as follows: Fold the
L7224A,C; L7248A,C,L OIL AND ELECTRIC BOILER
SENSOR WIRES
CONTROLLER CASE
IMMERSION
WELL CLAMP
IMMERSION WELL
CLAMP SCREW
Fig. 2. Position of sensor in immersion well.
Flush-Mounted Aquastat
Replacement
Turn off all power and remove the old control. Refer to
the cover insert of the old control 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.
Well-Mounted Aquastat
Replacement
Turn off all power and remove the old control. Refer to
the cover insert of the old control 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 control 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. 2
or 3. (See Replacement Sensor Installation sec-
tion for details.)
THERMOSTAT
TERMINALS
DISPLAY
SENSOR
ENVIRACOM
TM
CONNECTOR
TERMINALS
Fig. 3. Circuit board, showing sensor connection and
well holes for horizontal mount models.
3
BOILER
IMMERSION
SENSOR
WELL
HEAT-CONDUCTIVE COMPOUND
(OPTIONAL)
M16120
FUSE
SENSOR HOLES
68-0281—18
M32186
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