How to Buy a Tankless Water Heater

Tankless water heaters have been popular in Europe and Asia for many years, but only recently are they becoming more common in North America. They need much less space than a storage tank and are reportedly more energy efficient and last longer than storage tanks. Tankless heaters are about the size of a medicine cabinet and you can literally mount one on a wall. A water feed pipe runs into the tankless heater and is looped around inside then connected to your hot water pipes. When you turn on a hot water tap, the pressure of the water running through the pipes turns on a gas or electric heater and the water is warmed. When you turn off the tap, the heater shuts down until the next time you turn on a hot water tap. If you think a tankless water heater might be right for you, here are some points to consider.

Things You'll Need

• knowledge of your family's water usage patterns
• know the cost of energy for your home
• caluclator to determine if a tankless water will meet your needs

Instructions

Deciding whether to buy a tankless water heater

1. Consider how much water you use. The amount of hot water a tankless water heater can put out varies based on the temperature of the incoming (cold) water, how large the heating element is (its BTU output) and the demand for hot water. Tankless water heaters are sized based on their gallons per minute (g.p.m.) output.

2. Calculate your hot water demand by figuring the number of the hot water devices you would expect to use at one time, then total their flow rates (in gallons per minute). This is the flow rate the tankless water heater must be able to handle. For example, running a shower (flow rate 2.5 g.p.m.) and a faucet (flow rate 0.75 g.p.m.) means the water heater needs to be able to provide 3.25 g.p.m.

3. Determine the pressure of your water supply. Tankless water heaters require a minimum water pressure to operate; some homes won't have the necessary water pressure.

4. Consider your energy supplies. Both gas fired and electric tankless water heaters require significant amounts of energy when they are working. Depending on the existing supply lines to your home, this could require upgrading of either your electrical supply or your gas supply lines. In addition, gas fired tankless water heaters often require improved venting (to the outside) over and above what is necessary for a conventional gas fired storage tank. Check manufacturer's documentation and talk to a qualified electrician or gas fitter to determine if your home meets the tankless water heater's requirements.

5. Evaluate the energy savings provided by a tankless water heater. While the unit only consumes energy when water is flowing, it does require much more energy than a conventional water heater at those times. If having an unlimited supply of hot water means you will use more, there may not be any energy savings at the end of the month.

6. Think about water conservation. Tankless water heaters heat water as it passes through them. Water that is in the pipes between the heater and the faucet/shower/dishwasher will be cool. This water in the pipe will need to be drained before you get hot water coming out of the tap. Depending on the length of the water pipe in your home, you might need to run a tap for 30 seconds or more before you get any hot water.

7. Assess the initial cost of a tankless water heater versus a conventional storage heater. A tankless heater will cost in the area of $1,000 to $1,500 (depending on capacity) plus installation. Conventional water heaters would be in the $500 price range. Over time will the potential energy savings make up for the higher upfront cost?

Tips & Warnings

• While gaining in popularity, tankless water heaters are still not commonplace. Many contractors are unfamiliar with them, so be sure that anyone you deal with is manufacturer-certified.