Hydrolevel 450 User Manual

Low maintenance. No moving parts to wear stick or hang up,
as in float devices.

Solid state circuitry. Designed for the highest level of perfor-

450 Series

mance and reliability.
Automatically shuts off burner, after delay, in a low water

Low Water Cut-Offs
For Steam Boilers

120 VAC Operating Voltage
Max. Pressure 15 psi

condition to prevent dry firing.
Time delay allows water to feed above the probe to a safe

operating level.

HOW TO INSTALL

1 2 3

SAFE
WATER
LINE

1/4"

WARNING – To prevent electrical shock or
equipment damage, power must be off during
installation or servicing of the control. To pre­vent serious burns, the boiler should be thor­oughly cooled before installing or servicing con­trol. Only qualified personnel may install or ser­vice the control in accordance with local codes
and ordinances. Read instructions completely
before proceeding.

The probe may be installed in the boiler above
the lowest safe water level established by the
boiler manufacturer. Most manufacturers pro­vide a suitable opening in the side of the boiler.

R E M O T E M O U N T E D M O D E L S O N L Y

BA

A. To secure mounting plate to boiler jacket,* pre-drill two 3/32" pilot holes using the mount­ing plate as a template. Secure plate with sheet metal screws provided. Attach control to
mounting plate by slipping keyholes in back of chassis over pre-mounted screws on plate.
Tighten screws.

B. Using a wire nut, attach a wire (min 90°C) to the pigtail lead in the control box. Attach the
other end to the probe terminal in the remote probe housing. Attach a second wire between
the ground screw on the control chassis and one of the four screws in the remote probe
housing. Note: Wires and wire nuts not provided.

*Or other suitable surface

P.O. Box 1847
New Haven, CT 06508
Phone: [phone]
FAX: [phone]

Allow 1/4" clearance from the probe to any boiler
surface, tube or baffle. NOTE: Excessive use of
Teflon tape to seal probe piping threads may
insulate the control from boiler ground. This
could result in the control not operating.

4

Loosen the two control cover binding head
screws and remove the cover. Assemble the
chassis to the probe flange and secure with the
screws provided with the probe.

5

Connect the ring terminal wire lead to the probe
terminal stud and secure with the lock washer
and wing nut provided. With the power
removed, proceed with installation and wiring
according to the instructions on page 2. Upon
completion of wiring replace control cover.

+

0

LIMIT

CONTROLS

AP2P112

BURNER
CIRCUIT

HOT

NEUTRAL

FEEDER

OR ALARM

HOT

NEUTRAL

BURNER
CIRCUIT

AP2P112

BURNER

POWER

SOURCE

(24 or

120VAC)

BURNER

POWER

SOURCE

120VAC

AP2P112

FACTORY
INSTALLED
JUMPER

NEUTRAL

HOT

BURNER

POWER

SOURCE

120VAC

+

0

LIMIT

CONTROLS

AP2P112

HOTNEUTRAL

BURNER
CIRCUIT

120V

AC

AP2P112

REMOVE
JUMPER

NEUTRAL

HOT

+

0

LIMIT

CONTROLS

AP2P112

BURNER
CIRCUIT

HOT

NEUTRAL

BURNER

POWER

SOURCE

120VAC

+

0

LIMIT

CONTROLS

AP2P112

BURNER
CIRCUIT

WATER

FEEDER

WIRING METHOD A: SAME POWER SOURCE FOR CONTROL AND BURNER CIRCUIT.

A1

A1 Connect input voltage (120 VAC, 60 HZ)

to terminals 1 and 2. 120 VAC, 60 HZ must be
supplied to terminals 1 and 2 for internal opera­tion of the control.

A2 A3

A2 Connect terminal 2 to burner circuit neu-

tral. Connect terminal P2 to burner Circuit in
series with other limit controls. Consult boiler
manufacturer instructions for proper terminal
connections. Control should be wired in series
with and before other limit controls.

WIRING METHOD B: SEPARATE POWER SOURCE FOR CONTROL AND BURNER CIRCUIT.

B1

䊴

B1Remove jumper between terminals 1

and P1. Connect input voltage (120 VAC,
60 HZ) to terminals 1 and 2. 120 VAC 60 HZ
must be supplied to terminals 1 and 2 for inter­nal operation of the control.

A3 Optional water feeder connection.

Connect feeder N to terminal 2. Connect Feeder
H to terminal 1. Connect feeder “FEED” or “W”
to terminal A. For water feeders with 2 leads,
connect feeder neutral to terminal 2 and feeder
hot to terminal A. Note: Use of a solenoid valve

or McDonnell & Miller Model 101A water feeder
may cause flooding and is not recommended
for use with this low water cut-off.

B2

B3

䊳䊳

Connect hot lead from the burner

B2

control circuit to terminal P1. This terminal sup­plies power to terminal P2 in normal operating
conditions when water is at the probe. Connect
neutral to burner circuit. Note: consult boiler
manufacturer instructions for proper terminal
connections.

䊴

B3 Connect terminal P2 to burner circuit

B4

in series with and before other limit controls.

Optional water feeder connection.

B4

䊳䊳

Connect feeder H to terminal P1. Connect feeder
“FEED” or “W” to terminal A. Connect terminal
N to neutral of the burner circuit supply. For
feeders with two leads, connect feeder hot to
terminal A and connect feeder neutral to neutral
of the burner circuit supply. Note: Use of sole-

noid valve or McDonnell & Miller model 101A
water feeder may cause flooding and is not rec­ommended for use with this low water cut-off.