White Rodgers 11A79-2 User Manual

1 1A79-2

CAUTION

!

WARNING

!

Direct Immersion

WHITE-RODGERS

INST ALLA TION INSTRUCTIONS

Operator: Save these instructions for future use!

FAILURE TO READ AND FOLLOW ALL INSTRUCTIONS CAREFULLY
BEFORE INSTALLING OR OPERATING THIS CONTROL COULD CAUSE
PERSONAL INJURY AND/OR PROPERTY DAMAGE.

Hot Water Control

DESCRIPTION

This control is designed for use on hot water heating
systems.

It has a coiled element that is immersed directly into the
boiler water. This feature gives an unusual speed of
response to rapid changes of water temperature thereby
preventing thermal lag.

THIS CONTROL MUST BE INSTALLED BY A QUALI­FIED INSTALLER.

Do not exceed the specification ratings.
All wiring must conform to local and national electrical

codes and ordinances.
This control is a precision instrument, and should be

handled carefully. Rough handling or distorting compo­nents could cause the control to malfunction.

This control has been accurately calibrated at the factory.
Any attempt to calibrate this control will void the White­Rodgers warranty.

CAUTION

!

To prevent electrical shock and/or equipment
damage, disconnect electric power to system at
main fuse or circuit breaker box until installation
is complete.

This control has single-pole, double-throw switch action,
offering terminals that have open-on-rise switch action as
well as close-on-rise switch action. It may be used as a
high limit control, low limit control, circulator control, or as
a combination low limit and circulator control.

PRECAUTIONS

Shut off main gas to heating system until installa­tion is complete.

Label all wires prior to disconnection when ser­vicing controls. Wiring errors can cause improper
and dangerous operation.

Following installation or replacement, follow ap­pliance manufacturer's recommended installa­tion and/or service instructions to insure proper
operation.

Do not use on circuits exceeding specified volt­age. Higher voltage will damage control and could
cause shock or fire hazard.

If the boiler manufacturer recommends a control location,
follow such recommendations. If none is offered, the
following information gives suggested locations.

For high limit service, the control should be located in
the hottest part of the boiler. This is usually at the top of the
boiler. A high limit control should not be located in the
section of the boiler that contains the heat exchanger that
supplies domestic hot water.

For low limit or operating service, the control should be
located so that it responds to the temperature of the
section of the boiler that heats domestic hot water.

WHITE-RODGERS DIVISION

EMERSON ELECTRIC CO.
9797 REAVIS ROAD
ST. LOUIS, MISSOURI 63123-5398

R

When used as a circulator control, it may be located
near the boiler outlet or riser.

When used as a combination low limit and circulator
control, it should be located the same as suggested for

low limit service.
When tightening the control into the boiler, care should be

taken to apply all leverage to the hexagonal nut only to
avoid damage to the diaphragm or control mechanism.

Printed in U.S.A.

INSTALLATION

PART NO. 37-1022B

Replaces 37-1022-A

9520

NOTE

CAUTION

!

All wiring should be done according to local and
national electrical codes.

WHITE

4

3

BLUE

Open on rise
of temperature

Close on rise
of temperature

High
Limit

Ignition

Transformer

Burner

Motor

Common

RED

If the boiler or burner manufacturer recommends a wiring
diagram, then follow such recommendations. If none are
offered, the instruction sheet for the primary control (gas
valve or oil burner control) may offer some suggested
circuits.

Line Voltage

Oil Burner Control

1

T

2

T

The low limit side of the low limit/circulator control main­tains domestic hot water temperature all year around.
When the room thermostat calls for heat, the burner and

This control has a single-pole, double-throw snap action
switch. The top left-hand terminal (red) is the common
terminal. The top right-hand terminal (blue) has open-on­rise switch action. The bottom center terminal (white) has
close-on-rise switch action.

Limit Control: When used as either a high limit control or
a low limit control, use the open-on-rise terminals (red and
blue).

Circulator Control: When used as a circulator control,
use the close-on-rise terminals (red and white).

Combination Low Limit and Circulator Control: For
this application, all three terminals are used.

The following wiring diagram shows a typical circuit for an
oil-fired system with domestic hot water without storage
tank.

Combination

Low Limit-

Circulator

Control

R

B

W

Circulator

Thermostat

B

W

4

1

3

2

Relay

Type

809A-189

Hot

120V

Neutral

circulator operate. If boiler water temperature drops too
low, the circulator will stop until the temperature rises in
boiler.

SETTING THE CONTROL

1. Use a screwdriver in the adjusting slot (A) on the front
of the control to turn the dial so the fixed indicator (B)
points to the lowest temperature of the cycle.

2. Turn the differential adjusting screw (C) until the
movable indicator (D) points to the highest tempera­ture of the cycle.

“B” Fixed indicator

“F” Stop tab

“A” Adjusting

slot

The movable indicator points to the temperature at which
the contacts open on high limit and low limit applica-
tions. On circulator applications, the movable indicator
points to the temperature at which the circulator will start.

On combination low limit and circulator applications,
the movable indicator points to the temperature at which
the low limit will stop the burner and permit the circulator
to run.

(cut-in point)

“C” Differential adjusting

screw

“D” Movable indicator

(cut-out point)

“E” Stop screw

CONTROLS WITH ADJUSTABLE STOPS

1. Loosen stop screw (E) with enclosed wrench.

2. Set dial to original equipment manufacturer's specifi­cation.

3. Without moving the dial, move stop tab (F) against
indicator.

4. Re-tighten stop screw (E).

Setting stop higher than control being replaced
could cause personal injury and/or property dam­age.

2