How to Save Money on Tankless Hot Water Heater

There are several types of on demand hot water systems including: recirculating systems, demand type pump systems, thermo-siphon systems, and point-of-use water heaters. These systems may or may not save water in your home depending, upon your specific situation and the type of system you install.

Few studies have evaluated the water saving potential of these devices. A 2000 study in Westminster, Colorado evaluated on demand hot water systems in six homes and in a group of control houses (Mayer and DeOreo, 2000). This study found evidence of reduced shower usage in the six homes with the on demand systems. However, these six homes used more water for baths than did the control group. The combined shower and bath usage was identical between the two study groups. The study concluded that there was “no statistically verifiable overall savings” associated with the on demand hot water systems, either because of the effectiveness of the systems or because of the small sample size.

A recent unpublished study in San Jose, California evaluated on demand hot water systems in about ten single-family houses (de la Piedra, 2001). This study found very limited water savings in the study homes that were substantially less than the manufacturer had claimed.

If these devices are to included as part of comprehensive water conservation programs they must be shown, through independent evaluation, to save water. At this point water saving potential of on demand hot water systems is uncertain.

On-Demand Hot Water System Energy Savings

The manufacturers of on demand hot water systems claim that their devices can save $200 per year in hot water heating costs. If true, this would be a substantial savings. We were not able to locate any independent research studies that evaluated the energy savings of these devices.

Even without purchasing an on demand hot water system, lowering your water heater temperature between 10ºF and 25ºF, will save 5% to 15% of energy for water heating (U.S. Dept. of Energy, 2001).

Reducing hot water use and temperature is an excellent way to save energy. On demand hot water systems may be a good choice for reducing hot water demand, but there needs to be additional research to validate manufacturers claims of savings.

Benefits and Costs

Until independent verification of the water and energy savings from on demand hot water systems becomes available it is not possible to accurately calculate the benefits and costs of these devices.

On demand hot water systems start at around $200 and go up from there. There cost depends on the type of system purchased.

If the energy savings are in the neighborhood of $200 per year (as suggested by some manufacturers) then these devices would indeed be cost effective and the payback period would be easily within the life expectancy of the product.

Environmental Benefits

At this point, the environmental benefits of on-demand hot water systems are uncertain. Although these systems are designed to reduce water and energy use, there have been no conclusive studies that prove water or energy savings. More research is needed to determine what impact these systems have on the environment.

Future Trends

On demand hot water systems may have potential as a convenience product if not a water conservation device. Currently they cannot be considered a “must have” product like a clothes washer or dishwasher. Verified water savings will have to improve before utilities spend time and effort promoting these products.

The current stock of on demand hot water heaters could be improved by automating their operation. On many systems the user must activate a pump by pressing a button prior to using hot water. If this activation step could be tied to the faucet mechanism so that turning on the hot water faucet fixture automatically activated the pump, these systems would be much improved.

Point of Use
Point of use hot water heaters may offer an alternative to traditional hot water heating systems for some homeowners. These systems offer some advantages and disadvantage depending upon each individual situation. Point-of-use water heaters are also known as “tankless” heaters because they have no (or only a tiny) storage tank. They are relatively small units that provide hot water on demand. They use gas or electricity for fuel, and can be installed near demand points, such as under kitchen sinks. They are often more expensive than a conventional water heater, but can cost less to operate since they don’t maintain a tank full of hot water when not in use. A point of use heater typically provides 1-2 gallons of hot water per minute. Before installing a point of use water heater in your home, make sure its reduced capacity will be adequate for your needs.

On-Demand Hot Water System Research

Manufacturers are actively researching new on demand hot water heater designs, products, and technologies. However, since these are not particularly high volume sales items, research and development is often slow.

Few studies have evaluated the water saving potential of these devices. A 2000 study in Westminster, Colorado evaluated on demand hot water systems in six homes and in a group of control houses (Mayer and DeOreo, 2000). This study found evidence of reduced shower usage in the six homes with the on demand systems. However, these six homes used more water for baths than did the control group. The combined shower and bath usage was identical between the two study groups. The study concluded that there was “no statistically verfiable overall savings” associated with the on demand hot water systems, either because of the effectiveness of the systems or because of the small sample size.

A recent unpublished study by the Santa Clara Valley Water District in San Jose, California evaluated on demand hot water systems in about ten single-family houses (de la Piedra, 2001). This study found limited water savings in the study homes. These savings were substantially less than the manufacturer had claimed.

If these devices are to be included as part of comprehensive water conservation programs they must be shown, through independent evaluation, to save water. At this point water saving potential of on demand hot water systems is uncertain.

Add comment

Your email address will not be published. Required fields are marked *

Related Posts