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| OCCUPIED/UNOCCUPIED | |||
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| SWITCH | |||
NIGHT SETBACK THERMOSTAT
NOTES:
1.Occ/Unocc switch closes when occupied.
2.Night setback thermostat closes when in night setback heating.
Fig. 23 Ð Occupied/Unoccupied Switch with
Night Setback Thermostat
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| FIELD | |||||
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| SUPPLIED |
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| 3 |
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| V | POWER |
4 | 6 |
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| SIGNAL |
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| TO ROOM |
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| TERMINALS |
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Fig. 24 Ð Heat Interlock Relay
T10
12
RESET
P7 BOARD
15 
Fig. 25 Ð Accessory Reset Board
EXAMPLE:
T10 desired set point is 70 F.
T10R from Table 4 for 70 F is 5929 ohms.
P7R = 13,084 ± 5929
P7R = 7155 ohms
Using an ohmmeter, set the P7 potentiometer to 7155 ohms to achieve a reset initiation set point of 70 F.
Potentiometer P3 Ð Reset limit set point (maximum tem- perature value for modi®ed supply air set point). Maximum of 70 F, minimum 40 F. Set between leaving air set point (P1) and 70 F (maximum range permitted by control).
OPERATING SEQUENCE Ð If space temperature is above reset set point (T10 > P7), no reset will occur.
If space temperature is equal to or less that reset set point
(T10 < P7), the LED will display 20 and reset will begin.
Control will automatically adjust leaving air temperature by the following formula:
MSP = SP + [(P3 - SP) / 3] x (P7 − T10) |
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MSP = Modi®ed |
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SP | = |
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P3 | = Maximum | ||||
P7 | = Reset Initiation Temperature (reset set point) | ||||
T10 | = Actual Space Temperature |
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3 | = Ratio for reset (F) (®xed parameter) |
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| Table 4 Ð Thermistor Resistance and | ||||
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| TEMP |
| RESISTANCE |
| VOLTAGE |
| (F) |
| (Ohms) |
| DROP (v) |
| 31.0 |
| 16813.8 |
| 3.582 |
| 32.0 |
| 16345.7 |
| 3.553 |
| 33.0 |
| 15892.2 |
| 3.523 |
| 34.0 |
| 15452.7 |
| 3.494 |
| 35.0 |
| 15026.7 |
| 3.464 |
| 36.0 |
| 14613.9 |
| 3.434 |
| 37.0 |
| 14213.6 |
| 3.404 |
| 38.0 |
| 13825.5 |
| 3.373 |
| 39.0 |
| 13449.2 |
| 3.343 |
| 40.0 |
| 13084.2 |
| 3.312 |
| 41.0 |
| 12730.1 |
| 3.281 |
| 42.0 |
| 12386.6 |
| 3.250 |
| 43.0 |
| 12053.3 |
| 3.219 |
| 44.0 |
| 11730.0 |
| 3.187 |
| 45.0 |
| 11416.1 |
| 3.156 |
| 46.0 |
| 11111.5 |
| 3.124 |
| 47.0 |
| 10815.8 |
| 3.093 |
| 48.0 |
| 10528.7 |
| 3.061 |
| 49.0 |
| 10250.0 |
| 3.029 |
| 50.0 |
| 9979.3 |
| 2.997 |
| 51.0 |
| 9716.5 |
| 2.965 |
| 52.0 |
| 9461.3 |
| 2.933 |
| 53.0 |
| 9213.4 |
| 2.901 |
| 54.0 |
| 8972.6 |
| 2.869 |
| 55.0 |
| 8738.6 |
| 2.837 |
| 56.0 |
| 8511.4 |
| 2.805 |
| 57.0 |
| 8290.6 |
| 2.772 |
| 58.0 |
| 8076.1 |
| 2.740 |
| 59.0 |
| 7867.7 |
| 2.708 |
| 60.0 |
| 7665.1 |
| 2.676 |
| 61.0 |
| 7468.3 |
| 2.644 |
| 62.0 |
| 7277.1 |
| 2.612 |
| 63.0 |
| 7091.2 |
| 2.581 |
| 64.0 |
| 6910.6 |
| 2.549 |
| 65.0 |
| 6735.1 |
| 2.517 |
| 66.0 |
| 6564.4 |
| 2.486 |
| 67.0 |
| 6398.6 |
| 2.454 |
| 68.0 |
| 6237.5 |
| 2.423 |
| 69.0 |
| 6080.8 |
| 2.391 |
| 70.0 |
| 5928.6 |
| 2.360 |
| 71.0 |
| 5780.6 |
| 2.329 |
| 72.0 |
| 5636.8 |
| 2.299 |
| 73.0 |
| 5497.0 |
| 2.268 |
| 74.0 |
| 5361.2 |
| 2.237 |
| 75.0 |
| 5229.1 |
| 2.207 |
| 76.0 |
| 5100.8 |
| 2.177 |
| 77.0 |
| 4976.0 |
| 2.147 |
| 78.0 |
| 4854.8 |
| 2.117 |
| 79.0 |
| 4736.9 |
| 2.088 |
| 80.0 |
| 4622.4 |
| 2.058 |
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17