The Downflow Gas Furnace for Home Heating
Warm up With Natural Gas, Energy Efficiency and Heat Exchangers
Nov 28, 2008
There are three common types of gas air furnaces. The name implies the difference between them. The name specifies the airflow direction as it makes its way through the furnace past the heat exchanger, but the mission is the same; it keeps the home's occupants comfortable.
Types of Gas-Fired Furnaces
One type is the horizontal gas furnace. The air flows in a horizontal position. This type works in a crawl space where vertical space is at a premium.
The next type is the upflow gas furnace. Here, air flows from bottom to top. This has been the most commonly found heating furnace in the home.
Finally, enter the downflow gas furnace. In this case, airflow occurs from the upper part of the unit to the base. Next, the heated air makes its way from the unit's base through slab-mounted ductwork and is distributed through the residence.
How Does the Downflow Gas Unit Work?
In this type of gas-fired heater, natural gas is sent to a combustion chamber. There it's combined with available air. This mixture uses a pilot light for ignition. That flame heats the furnace's heat exchanger.
The heat exchanger is made up of metal tubing. The hot gases in the exchanger combine with the cooler air to be heated and pass over the heated surface of the exchanger. It then absorbs the heat provided by the exchanger.
The Importance of the Furnace Filter
Prior to the air entering the unit, before it's heated, it must pass through a filter. The purpose is to keep the furnace's interior uncontaminated. Two types of filters are common, washable filters and the disposable type. Washable filters do a better job but disposable filters entail less work when it comes to routine furnace maintenance.
A calibrated thermostat regulates the temperature of the living space when the homeowner sets it to the desired temperature. As soon as ambient air temperature drops below the set limit, the natural gas valve suppling the furnace opens up and combustion begins. As soon as the set temperature is detected, the gas valve shuts off. Just enough flow is left to keep the heater pilot light lit.
Be Aware of the Dangers of Gas Furnaces
As combustion occurs, vent gases occur in the form of deadly carbon monoxide. Vent gases are fatal to human beings and pets. It's critical that they're vented to the exterior of the residence.
Newer units are now available called ventless furnaces. They're designed to produce a negligible carbon monoxide footprint because of their improved energy efficiency. The amount of carbon monoxide produced is rated as having no appreciable effect on health.
The Carbon Monoxide Sensor Switch
These ventless units employ a sensor switch. It is installed to detect the level of deadly vent gas in the residence and has been engineered to shut down the furnace when a minimal percentage is detected.
It's always prudent to have a back-up indoor pollutant monitoring system to alert residents to not only carbon monoxide, but radon gas as well.
Regardless of which style of gas furnace is installed, it's critical to have the entire heating system tested on a yearly basis to ensure that it's serviceable and scores below an acceptable vent gas level.
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