• Home  / 
    • Blog  / 
    • Water Heaters
    •  /  On Your Search For The Best Hot Water Heater For Hard Water You May Ask: How Do You Protect Tankless Water Heaters From Hard Water?
    As an Amazon Associate we earn from qualifying purchases. Learn More.

    On Your Search For The Best Hot Water Heater For Hard Water You May Ask: How Do You Protect Tankless Water Heaters From Hard Water?

    Hard Water

    Hard water can play havoc with tankless water heaters. But by taking a few  precautionary actions  you'll not only save money, you can also prevent a major headache. Water hardness varies by geographical location, and the level of hardness is determined by the amount of dissolved minerals within the water supply.

    How Soft Water Becomes Hard Water

    Water that's relatively pure and mineral free is called soft water. Rain water starts out as soft water, but as it's absorbed into the ground, the water travels through soil and rock. Eventually, it finds its way to rivers, lakes and other bodies of water.


    As the soft rain water travels to its destination, it begins to absorb minerals from the ground. The more minerals the soft water absorbs, the harder the water becomes. 

    Hard water contains a high concentration of natural minerals, calcium carbonate and magnesium in particular. Although, not considered to be a health concern, hard water definitely causes problems for many of your home appliances.

    Lime scale build up on a heating element

    How Hard Water Affects Your Appliances

    As the hard water passes over the surfaces within your home, the minerals begin to separate from the water. Over time, the separated minerals form a scaly layer called limescale. 

    Water heaters are prone to limescale build-up, but so are sinks, dishwashers, washing machines, and even showers. Basically, anything that comes in contact with water can develop limescale.

    Why Descaling your Tankless Can Save it from Hard Water

    Both tankless water heaters and tank-style water heaters are negatively impacted by limescale build-up from hard water. But with tankless systems  the unit's expensive heat exchanger needs to work harder than necessary in order to heat the water.

    Since the heat exchanger becomes caked with limescale it's no longer capable of efficienctly transferring heat to the water.  In order for water to reach the desired temperature, the heat exchanger needs to go into overdrive.

    Effects of Limescale:
    • The heat exchanger will need to work harder to heat water because its caked with limescale. It will eventually overheat.
    • The heat exchanger will not reach it's service life potential and need to be replaced.
    • An error code could be triggered to shutdown the unit. A professional plumber may need to be called to get the unit up and running again.
    • As limescale build-up increases, the heat exchanger's burner cycles also increase in order to compensate for the lost efficiency. When this happens, the tankless is no longer saving you money on your fuel bills because of its lack of efficiency.
    • Manufacturer warranties do not cover damage caused by limescale build-up.

    How to Remove Limescale Build-up

    The good news is, once limescale build-up forms, it can be removed by flushing. Flushing a tankless water heater is critical to keeping it operating at it's peak performance, and to help it reach it's service life potential. Regular flushing is especially important if you live in an area with hard water. 

    >> How to flush a tankless water heater <<

    Manufacturer recommendations vary, but most suggest flushing your unit every 12 months. Although, keep in mind that, in the end, the frequency should be based on the area's water hardness. 

    Purchasing a set of inexpensive test strips can help you check the mineral content of your water.  Consulting with a professional can also be helpful, as he can give you his recommendation for the flushing frequency in your area.

    Man standing in front of 5 light bulbs

    Solutions to Hard Water Problems Affecting Your Tankless and Other Appliances

    Although limescale can be removed from your tankless water heater by regular flushing, the best solution is to prevent it from forming in the first place. Being pro-active can greatly reduce the affects of hard water. Below are a few options to consider:

    Scale Inhibitor System

    A scale inhibitor system is a relatively inexpensive way to protect water heaters from hard water. This system allows water to pass through a filter before it enters the water heater.  To make changing the filter easy, a shut off valve should be installed on the pipe on each side of the filter. 

    As the hard water enters your home, it will pass through the scale inhibitor filter BEFORE it flows into the water heater. This type of filtration system reduces limescale build-up by preventing minerals from bonding to the metal surfaces.  

    Consult with a Local Plumber

    Get FREE Quotes Today


    3M Aqua-Pure Whole House Scale Inhibition Inline Water System AP430SS, Helps Prevent Scale Build Up On Hot Water Heaters and Boilers

    Our favorite scale inhibitor system is manufactured by Aqua-Pure. Simply install it on the incoming cold water supply and it'll provide protection to your water heater as well as all of your water-using appliances, faucets, shower heads and pipes.


    Salt Based Whole-House Water Softener

    Both salt based and salt-free water softeners are a good fit for areas with extreme hard water. All of the incoming water to the house is treated, both hot and cold, so all of your appliances, fixtures and plumbing will benefit.

    Salt based water softeners are often the most affordable way to treat water. These systems completely remove the calcium and magnesium from the water as it passes through the water softener.

    The calcuim and magnesium is replaced with sodium ions, which is done by binding negatively charged potassium, sodium or hydrogen resin to positively charged metal ions. In other words, the hard minerals are literally drawn from the water. 

    As hard water enters your water softener, it flows through resin beads  which attracts and traps the hard mineral molecules. When the water enters your home, it's mineral free and considered soft.

    Over time the resin beads eventually are "full" of the hard water minerals. In order for the system to continue to soften your water, it'll need to run through a process called regeneration.

    Consult with a Local Plumber

    Get FREE Quotes Today


    Fleck 5600 SXT Water Softener Ships Loaded With Resin In Tank For Easy Installation (48,000 Grains, Blue)

    Fleck manufactures a whole house system that comes in a variety of size and color options. Simply plumb it into place, add salt and it's ready to use. This may be a more expensive option, but it's a quality product and more than capable of providing years of service.

    Watch the Video 

    Salt Free Whole-House Water Softener

    Salt free water softeners are also commonly called water conditioners or scale inhibitors. They function very differently than salt based water softeners as the hard water minerals are not removed from the water. 

    They do, however, still help prevent limescale build-up. Here are 2 common types of salt free systems:

    Catalytic

    The process used in these systems is called epitaxial crystallization, where the calcium is changed from a type that deposits limescale, to a type that does not. 

    The minerals are not removed from the water, but rather are allowed to pass through in a  stabilized  state leaving them unable to form limescale. 

    Nuvoh2o Dphb-a Nuvo Home System, 5" X 24 - New 2016 Model

    Nuvo's Home Water Softening System lowers the PH level of water. Each cartridge is designed to filter approximately 35,000 gallons of water before it needs to be replaced. Many people love this system, but it's not for everybody.

    Watch the Video 

    Electromagnetic

    Electromagnetic systems alter the ions of hard water minerals as the water flows through a magnetic field. The majority of systems on the market can be used on both metal and plastic pipes. 

    This is an easy-to-use system and many homeowners like that no chemicals are used in the process of treating water. However, there is some debate on the effectiveness.

    Eddy Electronic Water Descaler - Water Softener Alternative

    The Eddy Electronic Water Descaler is a popular choice if you're looking for an electromagnetic water softener. The company has been around for over 15 years and offers a 12-month, no questions asked return policy and lifetime repairs or replacement.

    Watch the Video 

    Water splashing

    Best Water Heaters for Hard Water

    Whether your water heater is tankless or tank-style, dealing with the affects of hard water requires a proactive approach. The methods shown above can help protect your water heater from limescale, and regular flushing will remove any limescale that has formed. 

    But which water heater is best suited for handling hard water? Well, this question can be a little misleading. If you live in an area where hard water is a concern, first and foremost consult with a professional.

    The money and time you spend upfront for a professional's expert advice is well spent. He'll not only be able to help you find the right water heater for your situation, but he can also suggest the best filtering system for your area.

    Selecting the Best Water Heater for Hard Water

    Have you ever heard the saying, "You get what you pay for"?  It may an old saying, but this general rule applies to purchasing a new water heater.

    Higher-end water heaters are manufacturered with better quality materials and components, and purchasing a system  from a reputable manufacturer can ensure good customer service for years to come.

    That's not to say, that you shouldn't help your water heater battle the affects of hard water, but a higher-end system may be a bit more forgiving. Here are a few units you may want to consider:

     

    Our Picks for Best Hard Water Tankless Water Heaters

    Stiebel Eltron Tankless Water Heater – Tempra 24 Plus – Electric, On Demand Hot Water, Eco, White
    Rheem 240V 3 Heating Chambers RTEX-24 Residential Tankless Water Heater
    Rinnai RUR Series Sensei SE+ Tankless Hot Water Heater: Indoor Installation
    Rheem RTGH-95DVLN-2 Tankless Water Heater, Grey
    Stiebel Eltron
    Rheem
    Rinnai
    Rheem
    Model
    Tempra 24 Plus
    RTEX-24
    RUR199iN
    RTGH-95DVLN-2
    Style
    Tankless
    Tankless
    Tankless
    Tankless
    Multiple Sizes Available
    Electric or Gas
    Electric
    Electric
    Natural Gas
    Natural Gas
    Rating
    Price
    $634.38
    $390.00
    $2,014.50
    $1,089.00
    Stiebel Eltron Tankless Water Heater – Tempra 24 Plus – Electric, On Demand Hot Water, Eco, White
    Stiebel Eltron
    Model
    Tempra 24 Plus
    Style
    Tankless
    Multiple Sizes Available
    Electric or Gas
    Electric
    Rating
    Price
    $634.38
    Rheem 240V 3 Heating Chambers RTEX-24 Residential Tankless Water Heater
    Rheem
    Model
    RTEX-24
    Style
    Tankless
    Multiple Sizes Available
    Electric or Gas
    Electric
    Rating
    Price
    $390.00
    Rinnai RUR Series Sensei SE+ Tankless Hot Water Heater: Indoor Installation
    Rinnai
    Model
    RUR199iN
    Style
    Tankless
    Multiple Sizes Available
    Electric or Gas
    Natural Gas
    Rating
    Price
    $2,014.50
    Rheem RTGH-95DVLN-2 Tankless Water Heater, Grey
    Rheem
    Model
    RTGH-95DVLN-2
    Style
    Tankless
    Multiple Sizes Available
    Electric or Gas
    Natural Gas
    Rating
    Price
    $1,089.00
     

    Stiebel Eltron Tempra 24 Plus

    Stiebel Eltron Tankless Water Heater - Tempra 24 Plus - Electric, On Demand Hot Water, Eco, White

    Stiebel Eltron has a large line of tankless water heaters. The Tempra 24 Plus may be the mid-sized unit in the line-up, but it's more than capable of delivering plenty of hot water to your household. With 24kW's, the Tempra 24 Plus can deliver a flow rate of 3.64 gpm with an incoming water temperature of 45°.

    Pros
    •  
       
      Uses the German patented Advanced Flow Control, which automatically reduces the flow of hot water in order to maintain the temperature when the demand exceeds the system's capacity. 
    • Solid copper heating modules.
    • Pre-set temperature memory buttons and a digital display that monitors the temperature and usage of the unit.
    Cons
    •  
       
      Quality comes at a price. Although less expensive than a gas tankless water heater, the Tempra 24 Plus is on the higher-end of the price scale for an electric tankless water heater.

    With it's sleek good looks and superior German engineering, Stiebel Eltron is an excellent choice. The Advanced Flow Control means you won't need to worry about running out of hot water when demand is higher than expected. 

    There's no need to hide this water heater in the basement, not only does it look good, but it runs virtually silent. And since it doesn't need to be vented, it can be installed nearly anywhere!

    Product Details
    • Flow Rate @ 45° Rise: 3.64 gpm 
    • Fuel: Electric
    • kW: 24 kW
    • Installation Location: Indoor
    • Dimensions: 16.5" H x 16.5" W x 4.5" D
    • Warranty: 7-year heat exchanger / 3-year parts

     

    Rheem RTEX-24

    Rheem 240V 3 Heating Chambers RTEX-24 Residential Tankless Water Heater

    The Rheem RTEX-24 is an excellent choice if your looking for a whole house electric tankless water heater. It's capable of delivering a flow rate up to 5.9 gpm, but if you need a more powerful unit, there are plenty of others in the RTEX to choose between.

    Pros
    • The electronic temperature control is easy to read and allows the unit to make 1° adjustments. Temperature settings can be made between 80 to 140°.
    •  
      Three Copper immersion heating elements are not only durable, but are threaded with a brass top for easy replacement. 
    •  
       
       
      Advanced self-modulation system can deliver 99.8% energy efficiency because it adjusts the power up or down to meet the hot water demand. 
    Cons
    •  
       
      Professional installation is recommended. Although, this is an additional expense, electric tankless water heaters are easy to install and having it done by a professional will give you peace of mind that its done correctly.

    Rheem is a top-notch brand, and their RTEX line-up is a favorite among consumers and professionals. Although the RTEX-24 is capable of servicing up to 3 showers running simultaneously, proper sizing is critical to your geographic area. If you purchase a unit too small, you'll most definitely be unhappy.

    You'll have plenty of installation options with the RTEX-24. It doesn't require venting so it can be installed nearly anywhere. The sharp, clean lines and classy finish means you don't need to tuck the unit out-of-sight. This is an excellent choice, and with proper maintenance, it'll last a very long time.

    Product Details
    • Flow Rate @ 45° Rise: 3.64 gpm 
    • Fuel: Electric
    • kW: 24 kW
    • Installation Location: Indoor
    • Dimensions: 18" H x 17.625" W x 3.5" D
    • Warranty: 5-year heat exchanger / 1-year parts

     

    Rinnai  RUR199iN

    Rinnai RUR Series Sensei SE+ Tankless Hot Water Heater: Indoor Installation

    The Rinnai RUR199iN is a powerful gas tankless water heater. It has all the bells-and-whistles you'd expect from a premium brand and it's capable of delivering up to 11 gpm of hot water. It's also the direct and updated replacement for the RUR98iN model.

    Pros
    •  
       
      This unit is ideal for homes without a dedicated return line. The ThermaCirc360 technology means you'll have hot water fast due to the built-in recirculation pump, timer and thermal bypass valve.
    •  
       
       
      The Uniform Energy Factor of .93 means nearly all of the energy used is going to heat your water. This is a very high score for a gas tankless and one of the reasons this heater is ENERGY STAR certified.
    • The included Control-R Module allows you to control the RUR199iN from an app on your phone. Adjust the temperature, activate recirculation,  and even allow for remote monitoring with a professional for maintenance or troubleshooting. With Control-R you'll be able to control your tankless even if you're on vacation!
    Cons
    •  
       
       
       
      The RUR199iN is a premium tankless water heater, but it's not inexpensive. It'll definitely add to the resale value of your home, but if you're planning on moving soon, it may not be worth the investment.
    •  
       
       
      Professional installation is recommended, and if your a DIY kind of person, keep in mind that improper installation may void your warranty.

    It's hard to go wrong with a Rinnai and the RUR199iN is an excellent choice. With one hundred years of experience behind the company, and one of the best warranty's in the industry, Rinnai has earned a reputation of being the best of the best. In fact, the average service life of a Rinnai is 20-years!

    If a part needs to be replaced, it can easily be swapped out with a new part. No need to purchase a whole new heating system. Although professional installation is strongly encouraged, that is the norm for all tankless water heaters. The RUR199iN has multiple venting options and does not require expensive Category III material, making installation easy for a professional.

    Product Details
    • Flow Rate @ 45° Rise: 8.5 gpm 
    • Fuel: Natural Gas
    • BTUs: 199,000
    • Installation Location: Indoor
    • Dimensions: 26.4" H x 18.5" W x 11.5" D
    • Warranty: 15-year heat exchanger / 5-year parts

     

    Rheem RTGH-95DVLN-2

    Rheem RTGH-95DVLN-2 Tankless Water Heater, Grey

    Part of Rheem's Prestige model line-up the RTGH-95DVLN-2 is the updated version. The main difference between the two models is a more powerful fan which enabled Rheem to reduce the intake air and exhaust vent ports from 3-inches to 2-inches.

    This high efficiency gas tankless water heater is designed for indoor use, although thereis a propane fueled unit and outdoor models in the same line-up.

    Pros
    • Freeze protection to -30° allows you to install the unit in garages and basements without worry.
    •  
       
      Rheem exclusive Hot Start Programming minimizes cold water bursts by keeping the unit in a ready-fire state when back-to-back hot water is needed.
    •  
       
       
       
      Connect to the EcoNet mobile app with the Tankless EcoNet Accessory Kit and you'll be able to monitor and adjust your tankless, as well as receive service alerts.
    Cons
    •  
      Although the unit is EcoNet Enabled and Circulation Pump ready, these extra features are not included and need to be purchased separately.

    With a pre-wired digital remote control, built-in condensate neutralizer, and an ultra low NOx burner the Rheem RTGH-95 DVLN-2 is ready for the most challenging hot water households. The unit is also capable of operating in altitudes up to 8,400-ft above sea level.

    This environmentally friendly tankless has a Uniform Energy Efficiency rating of .93, which is an impressive rating for a gas unit. The heating chambers are made of stainless steel, and the self-diagnostic system alerts you to maintenance and repair requirements. 

    Product Details
    • Flow Rate @ 45° Rise: 8.5 gpm 
    • Fuel: Natural Gas
    • BTUs: 199,900
    • Installation Location: Indoor
    • Dimensions: 27.5" x 9.8" x 28.5"
    • Warranty: 12-year heat exchanger / 5-year parts

     

    Consult with a Local Plumber

    Get FREE Quotes Today

    Last update on 2019-12-04 / Affiliate links / Images from Amazon Product Advertising API