Best Electric Tankless Water Heater – Buying guide
How does a tankless electric water heater work?
To quickly raise water temperature and create the impression of endless hot water, tankless heaters contain flow sensors, which detect when an outlet in your home is turned on.
When the sensor is tripped, the heater supplies electricity to the heating element, which is either a series of copper coils or an infrared device. The opposite happens when an outlet in the home is turned off, meaning that no energy is wasted at hot water creation is truly “on demand.”
Copper coils are the most common way of raising water temperature in tankless water heaters and are also often the cheaper of the two main heating elements. The more coils within a heating unit, the hotter water can get.
Infrared technology tends to be more expensive than the traditional copper coil, but they aren’t necessarily better.
Selecting the right size tankless water heater
The most important consumer decision when buying a tankless water heater is unit size. the size of a heater determines its flow rate, which in turn determines the number of appliances the unit can simultaneously supply.
It’s easy to find out what flow rate your home requires. Simply make a list of your plumbed outlets and appliances, and each of their individual flow rates. Some appliances will list rates on their casing/service panel, while others require a quick Google search or guestimation.
Average flow rates for common appliances are:
- Kitchen faucet: 2.5 gallons per minute
- Bathroom faucet: 2.5 gallons per minute
- Shower Head: 2.5 gallons per minute
- Toilet: 1.6 gallons per flush
- Washing machine: 15-25 gallons per load
- Dishwasher: 8 gallons per load
No home runs all of its appliances at the same time, so think about the daily maximum flow rate you’ll need. Most homes can run happily on tankless water heaters with flow rates between 4-10 GPM.
For small to average-sized homes, we recommend the Ecosmart ECO 18, which delivers a flow rate of up to 4.3 GPM. For larger houses, our pick is the Stiebel Eltron, with a flow rate of up to 7.5 GPM.
When judging flow rate, consider the ambient temperature of your water source. The lower the temperature of incoming water, the harder the unit will need to work to keep the desired temperature and flow of water.
Most heater companies supply information on flow rate based on ideal incoming water temperature, so be sure to factor in the specifics of your environment.
Tell me the difference between a tankless and tanked water heater
Electric heaters without tanks are generally less expensive than gas or tank models, both in unit price and monthly costs.
Even where the base price of electric tankless water heaters is higher, the investment is usually offset by savings on utility bills.
Without a tank to store water, electric heaters increase their energy efficiency by only heating what’s necessary and reducing wastage (known in the industry as standby heat loss).
Hot water demand
Even though tanked water heaters have the ability to store up hot water, they’re more likely to leave you shivering in the shower or frustrated at the kitchen sink.
When the tank in a traditional heater runs low, it can take a long time for the system to replace the supply. This can leave you fretting about how much hot water has been used during a day.
A tankless water heater supplies water on-demand to create the impression of endless hot water (assuming you have the correct flow rate for your needs). This is especially true in heaters without tanks that have an advanced flow control function, to help modulate the release of hot water.
Size and energy savings
A conventional water heater has large, multi-gallon tanks and bulky heating elements. This means they need lots of space—usually a laundry cupboard or boiler room. Modern heaters can be mounted on a wall, or even inside a shower cubicle.
Conventional tank-style water heaters are always operating, which eats up fuel and leaves a mark on your energy bills. A tankless unit only turns on when there’s a demand for hot water, meaning that you should see savings on your electricity bill.
Almost all tankless units will last for longer than tank heaters due to fewer moving parts and a more efficient heating process. The best electric tankless water heaters are designed to last up to 20 years, while conventional type water heaters have a service life expectancy between 8 and 12 years.
This difference in design also means that a tankless water heater can usually be serviced or replaced more easily than older models.
Maintaining a tankless heater
Heaters come with basic filter screens to help keep dirt and particulate matter out of the unit. Clean this filter screen regularly to avoid clogging.
Flushing or “de-liming” a heater is an important maintenance task to keep the element inside a water heater clean of chemical deposits and optimally functioning. This is usually done with vinegar or bleach.
We recommend installing a water filter [LINK] on the incoming water line to protect the unit. Many people also choose to add water softener [LINK] to reduce the number of corroding minerals running through the water heater.