Not too long ago, even the idea of having a high-efficiency electric water heater installed by a plumber would have been an oxymoron.

The cost of using this kind of water heater have been high for a long time, and as a result they’ve mostly been found in areas where gas lines couldn’t be run to a home.

Fortunately, that’s changing quickly. The technology and efficiency of electric water heaters has been making great strides recently, and better products are coming on the market as well. The tradeoffs are changing, so it’s important to be aware of the latest info to get the best possible high-efficiency electric water heater.

Know Your EF

Start with the efficiency rating. When it comes to water heaters, this is expressed as the Energy Factor (EF), and the way the number works is relatively simple.

• The higher the EF, the more efficient the electric water heater
• Most standard electric heaters have an EF of .75
• The new generation of high-efficiency electric water heaters is boosting that number to 0.9

If the electric water heater has a storage tank, that efficiency number can go up as high as .95. In that scenario, though, some heat is lost as the water moves from the storage tank through the heater and then up through the pipes into the house.

Tankless Electric Water Heaters

Another technology that has had an impact on the efficiency of electric water heaters is the move toward tankless. These heaters use electric coils to instantly heat a flow of water, after which it is used immediately. As a result, no tank is required to store hot water, so the efficiency is increased because no heat is lost due to cooling in the tank.

There is a catch, however. Water must be heated as fast as it can be used, and this is measured through a spec called temp rise, which is the amount of heat in degrees the heater can generate at a given number of gallons per hour flow rate.

A quick example: If water enters the heater at 50 degrees Fahrenheit and the desired temperature is 120 F, the heater must generate 70 degree rise at a flow rate that’s high enough to meet household demands.

Hybrid Hot Water Heaters

Another technology that must be included in the conversation is hybrid hot water heaters. These types of heaters use a heat pump along with electrical resistance to add heat.

To do this, the heat pump extracts latent heat from surrounding air, then transfers it to the water in the tank by using a head exchange device. It also incorporates resistance coils inside the tank to provide necessary heat to raise the water temperature to approximately 120 F.

Hybrids come with specific strengths and weaknesses, however. They typically use 60 percent less electricity than their strictly-electric counterparts, which means the EF rating can rise above 2.0.

The downside is that hybrid heaters tend to be taller than standard ones, and as a result they may not fit into existing water heater closets. Also, the heat pump releases a large amount of cold air through its exhaust, and that air must be vented away from the house.

All of this makes the buying decision somewhat more complex, with several factors that have to be evaluated. Let’s start with capacity.

Know Your Capacity

When considering a high-efficiency electric water heater, it’s important to match capacity with demand.

If the unit has a tank, a measurement called the First Hour rating is especially critical. This number specifies how many gallons of hot water the heater can produce in one hour at peak demand to meet a specific thermostat setting.

Knowing this number simplifies things enormously. Simply put, the FH must be above peak household demand to make sure everyone gets a hot shower.

Summary

The typical cost range for a high-efficiency electric water heater is from $1000-3000. Performance-wise, these units are usually anywhere from 100-300 percent more efficient than standard water heaters. With a conventional gas-fired hot water heater with a storage tank typically has an Energy Star EF between 0.67 and 0.70, so there’s plenty of room for improvement in that regard.

A new standard electrical hot water heater typically uses ten times more electricity than the average new refrigerator, so it’s more than worthwhile to consider the extra efficiency that’s coming on the market with electric water heaters.

To get the best possible product installed by an Arlington plumber, call Doherty plumbing and let us do the job right for you!