HVAC Ventilation Natural Ventilation

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HVAC Ventilation Natural Ventilation

The two natural forces available for moving air through and out of buildings are wind forces and temperature difference between the inside and the outside. Air movement may be caused by either of these forces acting alone, or by a combination of the two, depending on atmospheric conditions, building design, and location. Wind forces In […]

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HVAC Ventilation Air Leakage

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Air leakage caused by cold air outside and warm air inside takes place when the building contains cracks or openings at different levels. This results in the cold and heavy air entering at low levels and pushing the warm and light air out at high levels; the same draft takes place in a chimney. When […]

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HVAC Ventilation Requirements

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Ventilation is produced by two basic methods: natural and mechanical. Natural ventilation is obtained by open windows, vents, or drafts, whereas mechanical ventilation is produced by the use of fans. Thermal effect is possibly better known as flue effect. Flue effect is the draft in a stack or chimney that is produced within a building […]

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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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Heat-Pump Combinations

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There are four ways to describe the heat-pump methods of transporting heat into the house: 1. Air to air: This is the most common method. It is the type of system previously described. 2. Air to water: This type uses two different types of heat exchangers. Warmed refrigerant flows through pipes to a heat exchanger […]

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