If you’re in the market for a new water heater, you’re probably comparing tankless and storage water heaters. Not many years ago, no such comparison was possible. For decades, the conventional storage tank model totally dominated the U.S. market. These units provided acceptable performance and efficiency for most residential applications during eras of low energy costs. It was largely Japanese manufacturers in the 21st century who evolved tankless technology to accommodate their higher energy costs and tighter space requirements. Gaining market share every year, industry analysts now predict tankless water heaters will eventually represent 30 to 40 percent of U.S. installations.
Tank Versus Tankless Theory
A conventional storage tank heats water before its needed and stores it in the tank — typically a glass-lined, galvanized steel container with an average capacity of around 40 gallons. As the stored water waits in the tank, the burner periodically ignites so to keep the water at the desired temperature so it’s ready when a demand for hot water occurs.
Tankless models, on the other hand, heat water as needed. No water is stored, so no tank is required. When a hot water tap in the house is opened, the unit senses the water pressure fluctuation and instantly ignites a high-pressure gas burner that flash-heats the flow of water as it passes through the heater. When the tap is closed, the gas burner turns off.
What’s Good About a Storage Tank Heater?
- Low upfront cost – Simple in design and mass-produced by the millions to meet market demand, storage tank heaters are the most affordable option when considering initial cost.
- Uncomplicated installation – Storage tanks adapt well to the standard household water and gas pressure. When a new unit is necessary, a direct-fit replacement is usually readily avaliable.
- Wide availability – Virtually all plumbing contractors and suppliers sell and service standard storage tank water heaters.
- Low maintenance – Beyond regular flushing to remove mineral sediment, which is a simple DIY procedure for most homeowners, these units impose minimal upkeep requirement.
The Trouble With Tanks
Comparing tankless and storage water heaters means considering the downsides, as well.
- Energy losses – Despite its insulated enclosure, heat dissipation from a storage tank while the unit is idle is inevitable. Each time the water temperature dips below the thermostat setting, additional energy must be consumed to re-heat the water.
- Fixed capacity – The size of the storage tank limits the total volume of hot water available in any one short duration. If the tank capacity is depleted during a period of high hot water demand, additional hot water consumption is on hold until the unit can heat another tankful to the desired temperature.
- Limited life span – Tank corrosion is a factor due to electrolysis between the water and steel tank components. This limits a storage tank heater’s expected service life to an average of 10 years.
Tankless Talking Points
Comparing tankless and storage water heaters illustrates how elimination of the tank is the principal advantage of a tankless system.
- On-demand energy efficiency – A tankless system delivers only the volume of hot water required and only at the time it’s actually needed. No energy is wasted keeping a tankful of water hot 24/7.
- Unlimited hot water – Because it’s not limited by fixed tank capacity, a properly-sized tankless unit can continue to deliver hot water as long as the demand exists.
- Extended service life – Since tank corrosion isn’t a factor, most tankless models have life expectancy ratings of more than 20 years, which is twice the length of a storage tank heater.
- Sticker shock – A tankless heater with the specifications to fully replace an existing storage tank unit may cost as much as three times more upfront.
- Sizing is critical – Unless a tankless heater is carefully sized to the household demand by a qualified plumber experienced in tankless technology, performance may be disappointing or an additional heater may be required to take up the slack.
- Installation stipulations – Existing gas lines in the house may not be adequate to supply a tankless heater. Larger piping and a high-output gas meter may be required. Also, tankless heaters can’t utilize existing storage tank vents either, so new vent ducting must be installed.
- Professional maintenance – Annual de-scaling to remove lime deposits from the heat exchanger generally requires the expertise of a qualified professional technician.
Learn more about comparing tankless and storage water heaters, as well as their water heater options, from the professionals at Carefree Comfort, Inc. Heating & Air Conditioning, or give us a call at 847-388-0115.