Hydrolevel 400 User Manual

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

400 Series

Solid state circuitry. Designed for the highest level of perfor­mance and reliability.

Automatically shuts off burner, after delay, in a low water

Low Water Cut-Offs
For Steam Boilers

24 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

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.

1/4"

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

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]

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.

24VAC

HOT

COMMON

+

0

LIMIT

CONTROLS

AP2P112

BURNER
CIRCUIT

WATER

FEEDER

BURNER

POWER

SOURCE

24VAC

HOT

COMMON

BURNER
CIRCUIT

AP2P112

BURNER

POWER

SOURCE

BURNER

POWER

SOURCE

24

V

AC

+

0

LIMIT

CONTROLS

AP2P112

HOT

COMMON

BURNER
CIRCUIT

BURNER

POWER

SOURCE

24

V

AC

AP2P112

FACTORY
INSTALLED
JUMPER

COMMON

HOT

BURNER

POWER

SOURCE

24

V

AC

+

0

LIMIT

CONTROLS

AP2P112

BURNER
CIRCUIT

WATER

FEEDER

24VAC

AP2P112

REMOVE
JUMPER

24VAC

+

0

LIMIT

CONTROLS

AP2P112

BURNER
CIRCUIT

HOT

COMMON

BURNER

POWER

SOURCE

P2

2

1

AP2P112

AP2P112

WATER

FEEDER

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

A1 A2

A1 Connect input voltage (24 VAC, 60 HZ) to

terminals 1 and 2. 24 VAC, 60 HZ must be supplied
to terminals 1 and 2 for internal operation of the
control.

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

B1

B3

A2 Connect terminal 2 to burner circuit com-

mon. 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.

䊴

B1Remove jumper between terminals 1

and P1. Connect input voltage (24 VAC, 60 HZ) to
terminals 1 and 2. 24 VAC 60 HZ must be supplied
to terminals 1 and 2 for internal operation of the
control.

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
common to burner circuit. Note: Consult boiler

manufacturer instructions for proper terminal con­nections.

䊴

B3 Connect terminal P2 to burner circuit in

series with and before other limit controls.

Optional water feeder connection. B4

Connect feeder H to terminal 1. Connect feeder
“FEED” or “W” to terminal A. Connect terminal N to
common of the burner circuit supply. For feeders
with two leads, connect feeder hot to terminal A
and connect feeder common to common of the
burner circuit supply. Note: Use of solenoid valve

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

䊳䊳

䊳䊳

A3

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
common 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

B4

WIRING METHOD C: PLUG CONNECTOR.

C1

C2

䊴

C1Plug wire harness connector into matching end on circuit board. IMPOR-

TANT: Factory installed jumper must be in place between

terminals 1 and P1.

䊴

C2 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 common 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.