Category: Furnace

Lennox Pulse Furnace Troubleshooting

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Lennox Pulse Furnace Troubleshooting

Troubleshooting procedures for the Lennox Pulse furnaces are shown in Fig. 2-20. Figure 2-21 shows the circuitry for the G-14Q series of furnaces. Note the difference in the electrical circuitry for the G-14 and GSR-14. Blower speed color-coded wires are also indicated for the different units. The 40, 60, 80, and 100 after the G-14Q […]

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High-Efficiency Furnaces Combustion Process

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High-Efficiency Furnaces Combustion Process

The process of pulse combustion begins as gas and air are introduced into the sealed combustion chamber with the spark plug igniter. Spark from the plug ignites the gas-air mixture, which in turn causes a positive pressure buildup that closes the gas and air inlets. This pressure relieves itself by forcing the products of combustion […]

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High-Efficiency Furnaces Sequence of Operation

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High-Efficiency Furnaces Sequence of Operation

On a demand for heat, the room thermostat initiates the purge blower operation for a prepurge cycle of 34 s, followed by energizing of the ignition and opening of the gas valve. As ignition occurs the flame sensor senses proof of ignition and deenergizes the spark igniter and purge blower (see Fig. 2-18). The furnace […]

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High-Efficiency Furnaces Electrical Controls

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High-Efficiency Furnaces Electrical Controls

The furnace is equipped with a standard-type redundant gas valve in series with a gas expansion tank, gas intake flapper valve, and air intake flapper valve. Also factory installed are a purge blower, spark plug igniter and flame sensor with solid-state control circuit board. The standard equipment includes a fan and limit control, a 30-VA […]

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High-Efficiency Furnaces Operation

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High-Efficiency Furnaces Operation

The high-efficiency furnaces achieve that level of fuel conversion by using a unique heat-exchanger design. It features a finned cast-iron combustion chamber, temperature-resistant steel tailpipe, aluminized steel exhaust decoupler section, and a finned stainless-steel tube condenser coil similar to an air-conditioner coil. Moisture, in the products of combustion, is condensed in the coil, thus wringing […]

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High-Efficiency Furnaces

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High-Efficiency Furnaces

Furnaces have been designed (since 1981) with efficiencies of up to 97 percent, as compared to older types with efficiencies in the 60 percent range. The Lennox Pulse is one example of the types available. The G14 series pulse combustion up-flow gas furnace provides efficiency of up to 97 percent. Eight models for natural gas […]

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Hot Air Furnace Circuit Board Control Center

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Hot Air Furnace Circuit Board Control Center

Newer hot-air furnaces feature printed circuit control. The board shown in Fig. 2-8 is such that it is easy for the technician installing the furnace to hook it up properly for the first time. The markings are designed for making it easy to connect the furnace for accessories, if needed. Figures 2-9 and 2-10 show […]

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Hot Air Furnace Thermostat Location

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The room thermostat should be located where it will be in the natural circulating path of room air. Avoid locations where the thermostat is exposed to cold-air infiltration, drafts from windows, doors, or other openings leading to the outside, or air currents from warm- or cold-air registers, or to exposure where the natural circulation of […]

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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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