HEAT ANTICIPATION
Group A and Group B thermostats shown in Table 4 have a fixed heat anticipator for stage 1 with no adjustment required. Stage 2 has an adjustable anticipator for the W2 connection and fixed for the W3 connection. Both the W2 and W3 circuits are controlled by the stage 2 bulb. The only heat anticipator that needs to be checked is stage 2 and it should be set to match the load carried by the W2 circuit. The normal factory wiring provides for only one electric heat contactor to be controlled by W2, and the anticipator should be set at .40A. If special field wiring is done, it is best to actually measure the load but a good rule is .40A for each heat contactor controlled by W2.
THERMOSTAT INDICATOR LAMPS
The green lamp marked “Check” will come on if there is any problem that prevents the compressor from running when it is supposed to be.
COMPRESSOR MALFUNCTION LIGHT
Actuation of the green “Check” lamp is accomplished by a relay output from the heat pump control board which is factory installed. Any condition such as loss of charge, high head pressure, etc., that will prevent compressor from operating will cause green lamp to activate. This is a signal to the operator of the equipment to place system in emergency heat position.
TABLE 4
WALL THERMOSTAT AND SUBBASE COMBINATIONS
Thermostat | Subbase | Predominant Features | |
|
|
| |
- - - | 1 stg. cool; 2 stg. heat; Mercury bulb | ||
(T841A1761) | Manual changeover | ||
| |||
2 stg. cool; 2 stg. heat; Mercury bulb | |||
(T874R1129) | (Q674L1181) | Manual changeover | |
2 stg. cool; 2 stg. heat; Mercury bulb | |||
(T874N1024) | (Q674F1261) | Auto or Manual changeover | |
| 1 stg. cool; 2 stg. heat | ||
- - - | Electronic | ||
(T8511G1070) | |||
| Auto or Manual changeover | ||
|
| ||
|
|
| |
| 2 stg. cool; 3 stg. heat | ||
- - - | Programmable Electronic | ||
| Auto or Manual changeover | ||
|
| ||
|
|
|
IMPORTANT NOTE: The thermostat and subbase combinations shown above incorporate the following features:
Manual
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