Archive for January, 2011

Hot Air Furnace Low-Voltage Wiring

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Hot Air Furnace Low-Voltage Wiring

Make the field low-voltage connections at the low-voltage terminal strip shown in Fig. 2-7. Set the thermostat heat anticipator at 0.60 A (or whatever is called for by the manufacturer). If additional controls are connected in the thermostat circuit, their amperage draw must be added to this setting. Failure to make the setting will result […]

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Hot Air Furnace Field Wiring

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Hot Air Furnace Field Wiring

The installation of a new furnace requires you to follow a factory diagram furnished in a booklet that accompanies the unit. The wiring to be done in the field is represented by the dotted lines in Fig. 2-7. All electrical connections should be made in accordance with the National Electrical Code and any local codes […]

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Hot Air Furnace Manufacturer’s Diagrams

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Hot Air Furnace Manufacturer’s Diagrams

Figure 2-4 shows how the manufacturer represents the location of the various furnace devices. The solid lines indicate the line voltage to be installed. The dotted lines are the low voltage to be installed when the furnace is put into service. The motor is four speed. It has different colored leads to represent the speeds. […]

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Hot Air Furnace Ladder Diagrams

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Hot Air Furnace Ladder Diagrams

Electrical schematics are used to make it simple to trace the circuits of various devices. Some of these can appear complicated, but they are usually very simple when you start at the beginning and wind up at the end. The beginning is one side of the power line and the end is the other side […]

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Electric Heating System Basic Operation

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Electric Heating System Basic Operation

In Fig. 2-2, the electrical heating system has a few more controls than the basic gas-fired furnace. The low-resistance element used for heating draws a lot of current, so the main contacts have to be of sufficient size to handle the current. The thermostat closes and completes the circuit to the heating sequencer coil. The […]

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Basic Electric Heating System

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Electric-fired heat is the only heat produced almost as fast as the thermostat calls for it. It is almost instantaneous. There are no heat exchangers to warm up. The heating elements start producing heat the moment the thermostat calls for it. Various types of electric-fired furnaces are available. They can be bought in 5- to […]

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Basic Gas Furnace Operation

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Basic Gas Furnace Operation

The gas furnace is the simplest to operate and understand. Therefore, we will use it here to look at a typical heating system. This type of natural-gas furnace is used to heat millions of homes in the United States. Figure 2-1 is a simple circuit needed to control the furnace with a blower. Note the […]

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Hot-Air Furnaces

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Hot-air furnaces are self-contained and self-enclosed units. They are usually centrally located within a building or house. Their purpose is to make sure the temperature of the interior of the structure is maintained at a comfortable level throughout. The design of the furnace is determined by the type of fuel used to fire it. Cool […]

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