Honeywell T874G

69-0268—11 12

T874G,R MULTISTAGE HEAT PUMP THERMOSTATS AND Q674F,J,L SUBBASES

Home and Building Control

Honeywell Limited-Honeywell Limitée

35 Dynamic Drive

Scarborough, Ontario M1V 4Z9

69-0268—11 J.S. Rev. 12-95

If the setpoint lever setting and the thermometer reading

do not agree, follow the procedure below.

쐃Remove thermostat cover by pulling the bottom

edge of the cover outward and away from the base

until it clears the retaining posts.

쐇Set the cover on a table near an accurate

thermometer.

쐋After allowing five or ten minutes for stabilization,

compare the readings. If they are the same, replace

cover and put system into operation. If they are

different, recalibrate the thermostat thermometer;

see step 4.

쐏Insert a small screwdriver in the thermometer shaft

(Fig. 16) and turn it until the thermometers read the

same. When the thermometer is calibrated, replace

cover and place into operation.

NOTE: Radiant heat from your hands will offset the

thermometer reading. After making each

adjustment, wait five or ten minutes for the

thermometer to stabilize before comparing.

THERMISTOR RESISTANCE (ohms)

C815A THERMISTOR RESISTANCE

R = 400 ohms ± 10% AT 77°F (25°C)

4600

4400

4200

4000

3800

3600

3400

3200

3000

2800

2600

2400

2200

2000

1800

1600

1400

1200

1000

800

600

400

200

0-20 0 20 40 60 80 100 120 140

TEMPERATURE OF THERMISTOR (°F)

M1590A

Fig. 15. Thermistor resistance chart.

M5070

Fig. 16. Thermometer calibration.

Home and Building Control

Honeywell Inc.

1985 Douglas Drive North

Golden Valley, MN 55422