White Rodgers 5A75 User Manual

TYPE 5A75

WHITE-RODGERS

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.

The White-Rodgers combination warm air limit and single
speed fan control combines into one compact case, a switch
which controls the fan or blower operation and also a switch
which acts as a safety limit control.

The fan switch is designed to control blower operation. It will
start the fan circulating warm air when the bonnet temperature
reaches the pre-determined temperature setting; stopping the
fan and when the bonnet temperature falls below the pre­determined setting.

The warm air limit switch is designed to act as a safety switch
which automatically shuts off the burner when the furnace
temperature reaches a dangerously high point, regardless of
the cause.

The limit switch of these controls has special contacts which are
suitable for use on low voltage and millivolt (thermocouple
generator type) circuits as well as line voltage equipment such
as gas valves, oil burner motors, etc.

FAN & LIMIT CONTROL

INSTALLATION INSTRUCTIONS

DESCRIPTION

THESE CONTROLS 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 White-Rodgers
warranty.

If the furnace manufacturer has made provision for, or recom­mendations for location of this control, then follow those instruc­tions. If not, the following suggestions should be observed.

The temperature sensitive bulbs should be positioned in the
furnace bonnet so that they will be located in the area which is
subjected to the most rapid temperature changes.

WHITE-RODGERS DIVISION

EMERSON ELECTRIC CO.
9797 REAVIS RD., ST. LOUIS, MO. 63123
[phone], FAX [phone]

9999 HWY. 48, MARKHAM, ONT. L3P 3J3
[phone], FAX [phone]

Printed in U.S.A.

PRECAUTIONS

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.

WARNING

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

INSTALLATION

Avoid locations where there may be dead air spots or stratifica­tion affecting free air circulation. Corners, sharp turns, baffles or
other obstructions usually cause these conditions. Do not locate
the control elements where the air-flow from the bonnet into any
single duct will control its operation.

PART NO. 37-0874C

Replaces 37-0874-1 & 37-9098

9549

INSTALLATION (CONT.)

The elements should be bent so that they will not touch the
heated surface or be affected by reflected or radiated heat

unless such a position is determined by the furnace manu­facturer.

Care must be used when bending the element to prevent
“kinking” it. The element should not be bent with a radius of less
than one inch and all bending should be done between the coiled
part of the element and a point one inch from the diaphragm cup.
The element should be shaped over the thumbs so that a round
bend is obtained.

On remote controls, the long capillary tubing between the
sensitive bulb and the switch mechanism should be led over a
path that will protect it from cuts, blows, wear due to vibration,
etc.

Use the paper template packed with the control to obtain the
mounting dimensions.

ELEMENT
AFFECTED
BY AIR GOING
TO ONLY ONE DUCT

AIR FLOW OVER
ELEMENT AFFECTED
BU HUMIDIFIER

HUMIDIFIER

NORMALLY
GOOD ELEMENT
LOCATION

ELEMENT MAY BE
TOO CLOSE TO
SOURCE OF HEAT
UNLESS SUCH
POSITION IS
DETERMINED BY
FURNACE
MANUFACTURER

WIRING

All wiring should be done in accordance with local and national electrical codes and ordinances.

If the furnace or burner manufacturer recommends a wiring
diagram, then follow such recommendations. If none are of­fered, connect the fan side (right hand switch) as shown in the
diagram on this page.

Connect the limit side (left hand switch) according to wiring
diagrams packed with the primary control, gas valve, oil burner
control or stoker control.

SETTING THE CONTROL

LIMIT SWITCH WITH A FIXED DIFFERENTIAL

The indicator (B) points to the temperature at which the contacts
open.

To set the control:

Use a screwdriver in the adjusting slot (A) on the front of the
control to rotate dial until the desired temperature at which
the contacts will open is positioned directly under the
indicator (B).

REMOTE MANUAL SWITCH

FOR SUMMER FAN OPERATION

LIMIT FAN

TYPE
5A75

FAN

MOTOR

(IF USED)

HOT

LINE

N

CAUTION

The limit control is a safety device. The manufacturer of
the furnace as well as testing agencies (U.L., AGA, CGA)
have made many tests on the furnace to determine the
proper dial setting.

The limit dial should never be set any higher than the
setting it had when the furnace was delivered. Do not
force the dial past any stop on the dial even though the
dial may be graduated beyond the stop.

“F” STOP TAB

“E” STOP SCREW

“B” FIXED

INDICATOR

“A” ADJUSTING

SLOT

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. Retighten stop screw (E).

2