Computer Science for IGCSE & O level - Hardware (Section 24 - No. 32)
In central heating systems, what action is taken if the temperature reading is below the preset value?
The gas valve is closed.
The heater turns off.
A signal is sent to the heater.
The pump stops.
Giải thích
When the temperature is below the preset value, a signal is sent to turn on the heater.