Hot Air Furnace Ladder Diagrams
Wiring diagrams are used to make it simple to trace the schemes of different devices. Some of them may seem complex, but they tend to be very simple when you start early and wind up at the end. The beginning of one side of the power line and the end of the other side of the line. What happens between them is that the number of switches are used to ensure that the device is turned on or off, when it should be cooling, freeze or heat.
Relay logic makes it easier to see how these devices are connected. It consists of two wires were built in parallel and representation of the main power source. Along each side you will find the connections. Just look from left to right, you can track the required power for the device. Symbols used to represent devices. Usually there is a legend on the side of the chart to tell you that, for example, CC means compressor contactor, EFR means evaporator fan relay, and HR means, heating relay (see Fig. 2-3).
Look at the thermostat Fig. 2-3. The location of the switch determines whether the evaporator fan relay coil is energized, the compressor contactor coil is energized, or heating the relay coil is energized.
Once the coil, EFR is energized with the thermostat turned to get in touch with the right point G, he closes the points in the relay and evaporator fan, the motor begins to move. This means that the low voltage (24 VDC) relay energized. Relay energizes and closes EFR contacts that are in high voltage (240 in) circuit. If the thermostat turned to W or heating position, this will lead to a heating coil relay connection to power supply if the thermostat switch and covers the needs of heat. Encouraged by heating the relay coil causes HR to close contacts, which, in turn, puts a heating element of the entire 240-V and she begins to heat. Please note that the HR contacts in parallel with the evaporator fan relay contacts. Thus, the evaporator fan will run when either the heating relay or evaporator fan relay.