When was the last time you washed your dishes at 3am? Probably never, and yet if you have a tank-based water heater a huge percentage of your monthly utility bill goes to heating water at times when you don’t need it. Tankless* (or “on-demand”) water heaters can save you money in three major ways: they provide hot water only when you need it, where you need it and do not suffer from standby (when heated water is just sitting in the tank) heat loss.

* Tankless, on-demand, instantaneous, instant, flash, continuous flow, or inline are just different names to refer to a water heater that produces hot water quickly, and without a tank.

Does heating water really use that much energy?

It takes a lot of energy to heat water. An average 10 minutes shower uses about 20-40 gallons of water, depending on your water pressure and type of showerhead. Now imagine that you are heating just one gallon of water in a pot on the stove. If you think a lot of gas or electricity goes into heating that one pot, just imagine how much it energy is required just for one shower. The average American household spends about 13% of their utility bill on heating hot water alone.

What costs are involved?

Tankless water heaters come in both electric and gas varieties, both large and small. Usually they can produce about 2-5 gallons of hot water per minute (with gas heaters usually producing more than electric). Electric heaters generally run from $200 to $700, whereas gas is a little more expensive: usually $500 to $900 but also have a higher flow of hot water on average. Depending on what kind of tank you are using, its age, and efficiency, instant savings of 10% could be shaved off of your monthly utility bill by installing an energy-star rated tankless hot water heater and using hot water wisely.

What should I consider when buying?

First, it is important to consider how much hot water you really need, and where you need it. If you’d like to only use hot water for the shower, for example, then you can easily get away with the smallest of heaters, costing around $200 and installed directly in the shower stall. If, however, you’d like to supply your kitchen, laundry, hand sinks and showers all with hot water, then you would need a considerably larger heater, or a number of smaller heaters. The National Wildlife Federation offers a simple water calculator to help determine approximate water usage for a household. This can be found at: http://www.nwf.org/water/watercalculator.cfm

A second important consideration is whether you need a “full on/full off” heater or a “modulated” design. Full on/full off models are just that- they are either on or off and to be energy efficient would need to be turned on and off each time it is used. Modulated heaters have a water flow sensor and produce only as much heat as is needed to heat the flow of water at any given time. These, however, are generally more expensive than the on/off models.

What are the benefits?

Benefits:

• A constant supply of hot water, as there is no tank to empty
• Water comes out almost instantly hot, conserving both water and energy
• Hot water where you need it- in the shower, but not the sink (if you so choose)
• Hot water when you need it- in the morning rush, but not waiting for you at 3am
• Can adjust the temperature setting easily by turning a dial
• If the heater is installed where it is most needed (directly in the shower stall, for example) there is no heat lost in the pipes en route, and no hot water is left in the pipes after the water is turned off

Disadvantages:

• Requires an initial investment
• Smaller heaters may not be able to supply hot water for a whole household. Many smaller or one large may be necessary
• Due to the large amount of energy necessary to heat the water so quickly, some older homes may need to update some existing wiring in order to handle the energy load.
• There is some concern that widespread use of on demand water heaters will put too much strain on the electric grid system during peak times. If interested in helping the environment as much as possible, use at off-peak times.
• Still requires the use of electricity or gas

So should I go tankless or not?

CCI is an office environment, and we recommend that you keep your shirt on and remain clothed at all times. Wait, what? Oh! We were talking about tankless water heaters. Right.

The bottom line: If you are hoping to provide hot water to your whole household without a drastic reduction in water usage, you may find that other options such as an active solar water heater, a passive solar water pre-heater or simply a more energy-efficient tank heater would better meet your needs while reducing energy usage. If, however, you are hoping to dramatically reduce the amount of hot water you use (say, by using it only in the shower) then a unit installed directly where it is needed will likely be a good option with a small initial investment.

Something to consider: One of our staff members traveled through India last year where “geysers” (their word for tankless heaters) were the norm in the showers of guesthouses that offered hot water. Aside from being used in showers, hot water was not used for any other household chores. Pots were scrubbed until sparkling, clothes washed until fresh and hands rinsed until clean- all without the use of hot water.