The natural gas heater, sometimes called a natural gas furnace, is one of the most common ways homes are heated in the United States. With many changes over the years and a huge investment for any home, it is important to understand how modern natural gas heaters work. There are two main components to a natural gas heater.
Natural Gas Heater – Gas Valve
The gas valve is connected to the thermostat. When it signals that the desired temperature has dropped below the desired degree, it opens the gas valve. This allows
natural gas delivered through a gas pipeline to enter the heater. Cool air taken in by a circulating fan passes through a filter and is sent to the:
Natural Gas Heater – Heat Exchanger
This component is often made of a series of metal tubes, which retain heat caused by the ignition of the natural gas and cool air. The mixture of gas and air becomes hot air. The air is then blown out through the ductwork via an induced draft fan until the desired temperature is reached, forcing the thermostat to close the gas valve.
Now that you know the basics of how a natural gas heater works, there are other important facts to learn.
Natural Gas Heater – Annual Fuel Utilization Efficiency (AFUE)
This is the unit of measurement used to describe the efficiency of natural gas heaters and furnaces, as well as boilers and water heaters. An AFUE is expressed by a percentage which defines how much of the fuel is being used by the device. For example, if a natural gas heater has an 80% AFUE, this means that for every 100 BTUs of natural gas it takes in, 80 BTUs of useful heat are produced.
Forty years ago, gas heaters and furnaces typically had an AFUE of 65%. Today, the lowest allowable AFUE for a natural gas heater or furnace is 78%. This is a reason why old-fashioned oil burning furnaces have been mostly scrapped since even the most modern barely meet the standard. Today’s conventional natural gas heaters have AFUEs ranging from 78% to 84%. Conventional heaters that run on propane have higher AFUEs ranging from 79% to 85%, which can be beneficial in areas where propane costs less or the same as natural gas. But the natural gas heater with the best efficiency is the natural gas condensing heater with AFUEs ranging from 90% all the way up to a whopping 97%.
Natural Gas Conventional Furnace vs. Natural Gas Condensing Furnaces
As new technology develops, new developments in natural gas heating occur. One of the newest is the emergence of a natural gas condensing furnace. It works in a similar manner to the conventional furnace, but with an improved form of heat exchanger. Whereas a conventional natural gas furnace heats the air once and disposes of the remaining water vapor, a condensing furnace utilizes it. With the use of a second heat exchanger, a condensing furnace extracts and heats the water vapor to be blown through the ductwork in addition to the initially heated air.
With the extra components, a condensing furnace usually costs more than a conventional one. However, the costs saved from using less fuel and longer life span can offset the price of a condensing unit. If you have a relatively new conventional furnace and don’t live in an area with long, harsh winters, a condensing furnace may not be right for you. If in the market for a new furnace in a region with harsh and lengthy winters, a natural gas condensing furnace can pay for the extra cost versus a conventional furnace in a short amount of time.
Updraft Natural Gas Heaters vs. Downdraft Natural Gas Heaters
These types of heaters are chosen based on the type of structure they go in. The mechanisms for the heating process are similar no matter which of these heaters is chosen. However, the building they go into can have a high impact on energy efficiency.
In updraft natural gas heaters, at times called upflow heaters, cool air enters through the bottom of the unit, with heated air sent through the ductwork above. This type
of heater is generally found in traditional one or two story homes and for those with basements. It is also commonly found in regions where the weather tends to be warmer.
In a downdraft natural gas heater, sometimes called a downflow heater, unheated air enters from the top of the unit and exits through the bottom of the unit. These heaters are installed on the main floor of the house and work best in conjunction with ductwork that uses floor vents. This is advantageous because heated air rises.
Other Important Components to a Natural Gas Heater
The Flue – Working similarly to the flue on a fireplace, its function is to keep harmful gas from entering the home. When igniting natural gas, harmful carbon monoxide gas is produced by the heater. The flue routes this gas out of the home.
The Condensate Drain – Natural gas heaters also produce water vapor which can return to its liquid state when cooled. The function of the condensate drain is to take in this water and drain it away from where it can damage the home.
Humidifier – An optional addition to a natural gas heater, a humidifier works by adding moisture to the air, which can be useful to those with allergies or other respiratory distress. There are two types of mounted humidifiers. The first is the reservoir which uses a reservoir of water and rotating drum to produce moisture in the air. However, because the humidifier uses standing water, there is a chance for bacteria growth in the reservoir. This is why flow-through humidifiers have become the standard. Water is flowed through the unit as needed which both creates the desired moisture and eliminates the possibility of hazards from standing water.
Other Important Facts About Natural Gas Heaters
- Newer models come with electric ignitions which eliminate the need to check, light, and re-light pilot lights.
- Newer heat exchangers are stainless steel and last much longer than old “pig iron” units. If registered with the manufacturer at the time of installation, most units have 20 year warranties.
- Size matters. Heaters that are too small will not be able to efficiently heat your home. Heaters that are too big not only come with a heftier price tag, they cycle on and off more frequently and cause unnecessary wear to its components. A heater’s size also must be matched to an AC unit’s size if you have AC. Since the conditioned air is pushed through the system by the heaters fan, the two units must be of compatible size.
- Filter replacement is one of the best ways to maintain a natural gas heater. However, the process is different from changing an air conditioning filter. Check your heater’s manual for directions on how along with the recommended frequency.
- If your house is too cold or too hot even though the thermostat reads at a comfortable temperature, it is a sign of a faulty thermostat. Try changing the batteries to see if it helps.
- Get regular maintenance. Having a qualified technician come into to perform needed maintenance can add years to the life of the unit. Routine maintenance includes cleaning, checking belts, oiling the motor, and checking the venting/flue to ensure no blockage has occurred.
- One of the best safety tips for natural gas heaters is the purchase of a carbon monoxide detector. The gas is odorless and can be highly toxic. The detectors are cheap, can be found in most home improvement stores, are easy to install, and can alert you the instant there is an issue.