Gas Hot Water Heaters
We use a variety of different energy sources for heating the water we use in our homes, including various fossil fuels, one of which is gas. There are two basic fuel types we use for gas hot water heaters:
- natural gas, and
- liquefied petroleum gas.
Then there are two basic types of gas heater to choose from. The first is the sort that incorporates a tank in which the water is stored, and the other doesn't have a tank at all. But when you start examining the differences between different units more closely, including their parts and the way they work, you will find that there are some quite profound differences. Of course you will also find that prices vary quite considerably too.
Types of gas heaters
In addition to conventional water heaters that rely on gas to heat the water, there are also tankless gas heaters and hybrid gas heaters.
Conventional
Nowadays so-called conventional gas water heaters are available in the form of standard energy-efficient and high efficiency designs that may be used with both propane and natural gas, either supplied in cylinders or piped to our homes by the gas supply authority. But this doesn't make them ordinary. In fact conventional gas water heaters have never been more "unconventional" (or out of the ordinary) than they are today.
New age models offer all kinds of features, from power vents and pressurized combustion chambers that don't leak, to high efficiency units with automatic flue dampers and electronic gas controls.
Tankless
Traditionally gas water heaters were tankless, and many were manufactured specifically to be instantaneous hot water heaters. Like electric water heaters, when the faucet of a tankless unit is turned on, a flow switch will activate the burner that heats the cold water. The water heats quite quickly to the temperature that is required, and then stops heating when the faucet is turned off.
Today tankless gas water heaters that run on gas feature increased flow rates, superior PVC venting, and most high quality models are highly efficient energy wise.
Hybrids
Hybrid designs combine features of both conventional water heaters and those that are tankless. For instance some use a heat transfer process that uses a secondary heat exchanger to trap the gas from the unit and channel it back through a buffer tank where it is able to extract more heat.
Good models boast really good (up to 90%) thermal efficiency and can also handle high demands for hot water. The best models are also simple to install and probably the best type to opt for.
Advantages of gas water heaters
Instantaneous gas water heaters are ideal for people who live where electricity is not available, where electricity is very expensive, or for holiday homes where people don't want to spend money on an expensive electric installation.
Instant water heaters that are fired by gas also tend to provide a flow rate that is much higher than instant water heaters that are run using electricity. And the best news is that state-of-art products that are now being produced are able to cope with a continuous need for hot water (this used to be a huge disadvantage).
Disadvantages of gas water heaters
Most conventional old-fashioned gas water heaters will not allow you to operate more than one appliance at any one time. However there are now a growing number of models that enable you to operate two major hot water applications at one time.
Alternatively, depending what is available to you, and what you can afford, the answer may be to install two or more instantaneous or on-demand heaters to allow you to bath or shower at the same time as you are using a washing machine or dishwasher to clean clothes or dishes.
Another traditional disadvantage is that gas-fired units have been known to waste energy, especially the type that has a pilot light which is left to burn constantly. The implicit costs of operating gas-fired units with pilot lights vary though, so it is a good idea to check what these will be before you actually purchase a gas water heater. If this information is not available from the manufacturer, reconsider your decision to buy this particular unit (they might be hiding something). Today some models are fitted with various intermittent ignition mechanisms that do not stay on permanently. Alternatively you could simply turn the pilot light off manually, and then relight it when you need to heat the water again. There are also top range models that allow you to operate the unit without a standing pilot light.
Energy efficiency
While some gas-fired water heaters do waste energy, in recent years manufacturers have been making an attempt to make models that are considerably more energy efficient than they used to be. So, for instance, you'll find that there is often a choice between "standard energy-efficiency" and "high-efficiency" designs.
On average though, instantaneous water heaters that operate with gas (particularly natural gas), are rated more energy efficient that gas units that incorporate a tank.
It can certainly be a challenging task to try and ascertain which is the very best gas hot water heater available. To be able to do this, you need to compare the features and advantages – as well as any potential problems – of all the units you like. Read every review you can find, and see how they each one compares in terms of rating. If you live in the US, look out for designs that are eligible for Federal Tax Credit. Wherever you live, try to stick with Energy Star rated units.
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