Have you noticed a strange film on your hands after washing them, spots on glasses fresh out of the dishwasher, or soap scum on the tub? This is likely due to hard water.
Hard water, water with heavy concentrations of minerals in it, is not just an annoyance – it can also slowly deteriorate the plumbing and appliances in your house, including your tankless water heater!
To avoid the costs of repairs and early water heater replacement, you need to buy the best tankless water heater for hard water conditions.
In this PlumbingNav guide, we will cover:
Different types of tankless water heaters for hard water
How does a tankless water heater work?
What should I look for when looking for a tankless water heater for hard water?
Review of 5 Best Tankless Water Heaters for Hard Water
This compact electric tankless water heater produces up to 8.7 GPM of hot water in both indoor and outdoor settings at 99.8% efficiency. You can see the temperature on the digital display and change the temperature with the knob on the unit. It has a copper heat exchanger that can be easily replaced if necessary, and it comes with a limited lifetime warranty.
Our Top Tankless Water Heaters for Hard Water
Quickly uncover our picks for the top 5 tankless water heaters for hard water before we go over the topic in more detail.
What Are The Best Tankless Water Heaters For Hard Water
The best tankless water heaters for hard water contain heavy-duty heating elements that can withstand the sediment buildup that develops inside of the unit as a result of the high mineral content in the hard water.
Sediment buildup on the heating element can hinder its ability to communicate with the thermostat, causing the device to produce water at scalding temperatures. To prevent this from happening, you can buy a tankless water heater that includes heating elements made out of durable material.
Types of Heating Elements
The main difference between the types of heating elements comes down to the material used to create them.
A mixture of stainless steel and nickel creates high-end heating elements known as ultra low watt density elements. These heating elements have a larger surface area, giving them the ability to spread out the heat, lowering the temperatures it faces and reducing damage.
The materials increase the component’s ability to thwart off calcium deposits and corrosion, allowing it to last longer under hard water conditions.
High watt-density heating elements, on the other hand, contain copper and zinc. These elements generate a large amount of heat, making them more vulnerable to damage. The copper doesn’t protect against the sediments buildup as well, either.
For the best tankless water heater for hard water, pick a device with ultra-low density stainless steel heating elements.
What Are The Different Types Of Tankless Water Heaters For Hard Water?
The two types of tankless water heaters for hard water are gas tankless water heaters and electric tankless water heaters. Both options can withstand hard water if you get the right hot water heater, but they have other distinctive features that make each one better in certain situations.
Gas Tankless Water Heater
Gas water heaters heat the water using a gas burner with a direct flame to ignite the heat exchanger, which heats the water.
Gas doesn’t cost as much as electricity, and gas water heaters tend to heat water more quickly.
Also, many high-efficiency condensing gas water heaters provide efficiency ratings that match the efficiency levels of electric water heaters.
However, gas tankless water heaters cost more both for the unit itself as well as the more complicated installation. The direct heat can also increase the likelihood of sediment buildup, requiring more frequent maintenance.
Electric Tankless Water Heaters
Electric tankless water heaters use indirect heat to spark the heat exchanger. Since the process generates less heat, it takes slightly longer to heat the water. This also leads to high energy efficiency levels, and more protection from sediment build-up than gas water heaters, which is exactly what you need when you have hard water.
However, electric water heaters don’t produce the same power as gas water heaters, and electricity costs more than gas.
How Does A Tankless Water Heater For Hard Water Work?
Efficient tankless water heaters produce hot water on demand as opposed to tank-style units that constantly run to keep the water in the tank warm, making tankless water heaters much more efficient than traditional tank-style water heaters.
When you turn on the hot water faucet, water comes into the unit at the cold water supply line. When this happens, it activates the heating element, which heats the water. The hot water then travels to the open faucet.
The hot water flows continuously until you close the faucet or additional faucets demand a higher water flow rate than the unit can provide.
What Do You Look For In The Best Tankless Water Heater For Hard Water?
When looking for the best tankless water heater for hard water, you need a tankless water heater that can accommodate your home’s needs and the initial expense compared to the monthly savings.
Water Flow
Unlike tank-type water heaters that use a tank, tankless water heaters measure the size of the unit based on water flow in gallons per minute (GPM).
To ensure you get the correct size water heater, first determine how much water your family uses at peak hours. Use the following estimates to determine the proper flow rate for you:
2 bedroom/1 bathroom – 6 GPM
2 bedroom/2 bathroom – 10 GPM
3 bedroom/2 bathroom – 12 GPM
4 bedroom/2 bathroom – 14 GPM
4 bedroom/3 bathroom – 16 GPM
5 bedroom/3 bathroom – 18 GPM
Keep in mind that tankless water heaters provide better water flow rates in warm climates compared to cold climates. Be careful to check the rating of possible units in your area.
See the video below for help finding sizing information:
Costs
You need your tankless water heater to fit into your budget, so analyze the costs associated with your tankless water heater before you make a purchase.
Tankless water heaters tend to require a higher initial investment, but they last up to 20 years and also tend to save money in the long run.
Electric tankless waters won’t cost as much upfront, and they have some of the highest efficiency levels.
If you prefer gas tankless water heaters, you can choose between non-condensing and condensing models. Condensing models cost more, but they run more efficiently.
Best Tankless Water Heaters For Hard Water Reviewed
Now let’s explore our favorite units so you can decide on the perfect choice for your situation.
This compact electric tankless water heater produces up to 8.7 GPM of hot water in both indoor and outdoor settings at 99.8% efficiency. You can see the temperature on the digital display and change the temperature with the knob on the unit. It has a copper heat exchanger that can be easily replaced if necessary, and it comes with a limited lifetime warranty.
The Rinnai RL+ series uses gas to generate up to 9.8 GPM of hot water, which can provide a whole home hot water system for an average two- to four-person household. It uses a non-condensing design and runs at an efficiency level of .82.
Rinnai offers a limited 12-year warranty on the copper heat exchange and a five-year limited warranty on all other parts and components.
Receive a water flow of up to 6 GPM with this electric tankless water heater. The device uses advanced self-modulating technology to learn your habits, reducing energy usage and contributing to its highly efficient operation.
This device comes with a protection against leaks for seven years and three-year warranty on the parts, including the copper heating elements.
This easy to use Rheem electric tankless water heater shows the temperature on the digital display and uses one knob to control the temperature. Self-modulating control increases the ultra-high 99.8% efficiency of the device as it produces up to 5.9 GPM.
This Rinnai tankless gas indoor water heater operates at .93 efficiency due to its condensing technology to produce up to 9 GPM. You can read and change the temperature on the clear digital display, and you can even install an optional WiFi connectivity module. The copper heating elements come with a 10-year warranty.
Pros
7.5 GPM
WiFi compatible
.93 Efficiency
Cons
Expensive
Indoor installation only
Heavy at 62 pounds
Final Thoughts On Tankless Water Heaters For Hard Water
When you live in an area with hard water, the mineral deposits left behind can affect your water heater, and the heating element in particular. Copper ultra-low watt heating elements provide the best protection.
Yes. Hard water leads to more sediment buildup in the tankless water heater, which can damage the heating element.
Is a water softener required for a tankless water heater?
While not required, your water heater (and the rest of your plumbing and appliances) will benefit from the use of a water softener if you have hard water.
How long do tankless water heaters last with hard water?
Even with hard water, tankless water heaters can last up to 20 years. However, this assumes that you perform regular maintenance.
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About Plumbing Navigator
We write about "all things plumbing," helping you navigate common questions, repairs, and the best plumbing products on the market.
About Plumbing Navigator
We write about “all things plumbing,” helping you navigate common questions, repairs, and the best plumbing products on the market.
