White Rodgers 5A75 User Manual

TYPE 5A75

WHITE-RODGERS

FAN & LIMIT CONTROL

INSTALLATION 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.

DESCRIPTION

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.

PRECAUTIONS

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.

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.

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.

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.

						WHITE-RODGERS DIVISION
						EMERSON ELECTRIC CO.
						9797 REAVIS RD., ST. LOUIS, MO. 63123
						[phone], FAX [phone]	Printed in U.S.A.
						9999 HWY. 48, MARKHAM, ONT. L3P 3J3
						[phone], FAX [phone]

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.

REMOTE MANUAL SWITCH

If the furnace or burner manufacturer recommends a wiring

FOR SUMMER FAN OPERATION

diagram, then follow such recommendations. If none are of-

LIMIT FAN

(IF USED)

fered, connect the fan side (right hand switch) as shown in the

TYPE

diagram on this page.

5A75

Connect the limit side (left hand switch) according to wiring

diagrams packed with the primary control, gas valve, oil burner

HOT

control or stoker control.

LINE

N

FAN

SETTING THE CONTROL

MOTOR

LIMIT SWITCH WITH A FIXED DIFFERENTIAL

CAUTION

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

The limit control is a safety device. The manufacturer of

open.

the furnace as well as testing agencies (U.L., AGA, CGA)

To set the control:

have made many tests on the furnace to determine the

Use a screwdriver in the adjusting slot (A) on the front of the

proper dial setting.

control to rotate dial until the desired temperature at which

The limit dial should never be set any higher than the

the contacts will open is positioned directly under the

setting it had when the furnace was delivered. Do not

indicator (B).

force the dial past any stop on the dial even though the

dial may be graduated beyond the stop.

	“F” STOP TAB	“B” FIXED
		INDICATOR

“A” ADJUSTING

SLOT

“E” STOP SCREW

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