Bioenergy, Solar

Is a Tankless Water Heater System a Wise Choice?

I am researching tankless hot water heaters to replace my traditional unit. My house has all electric, no gas. Basically, are electric tankless systems efficient? — Brian D., New Market, MD.

Brian, Tankless water heaters penetrated the European market way before the U.S. According to Rheem, headquartered in New York, a 64-gallon per day system (around 9 cents per kilowatt-hour) should cost you around $460 per year. The theory is that you are only expending energy to heat water ‘when you need it’ thus no need to store water and keep it warm. Overall this is true. On the other hand, conventional solar water heating systems, particularly thermosyphon or those using pv-powered circulation pumps, require no (or minimal) input of electricity — and in my home, need no backup with a super-insulated water tank. Other types of water heating systems using waste heat from furnaces (in winter) or from ground-coupled heat pumps can also be very efficient. For those sticking with conventional water heaters, at least purchase insulating blankets sold in the major hardware chains for your water heater, to keep the heat in the tank, not in the air. Depending on whose data you use, from 10 to 15 percent of the energy in your building is used to heat water — so carefully selecting energy systems will save you money in these times of steeply rising natural gas and electricity rates. – Scott Sklar