Water Heaters – Complete Range of Hot Water Solutions

Do you know that the tankless water heaters provide hot water on demand? Not only are tankless water heaters more energy-efficient, they last longer, but also require less maintenance and repairs, and use less space.

The tankless water heaters pump out hot water at a rate of 2-5 gallons per minute (GPM), making them a better and more energy-efficient source of hot water compared to conventional storage water heaters. Plus, you can enjoy hot water on demand without while avoiding higher utility bills.

It is essential to learn your way around the market as there are several factors to consider before choosing tankless water heater units. With these reviews, you will learn everything you need to know and why you should consider getting one for your home before the fall or winter.

What Is a Tankless Water Heater?

What-Is-a-Tankless-Water-HeaterA tankless water heater is an appliance that provides hot water on demand. Unlike the traditional storage water heaters that heat water continuously in a tank, tankless water heaters heat water as needed, eliminating the need for tank storage.

Tankless water heaters are not a novelty as they have been in use for a long time in Europe and parts of Asia such as Japan. However, the United States has recently caught up with these appliances.

Tankless water heaters have several advantages over their conventional tank heaters. They are more energy-efficient and can help cut your energy bills and conserve natural gas. They also take less space, last longer, and provide a ready supply of hot water on demand.

However, tankless water heaters are more expensive to buy, and can also come with substantial installation costs, with some systems requiring extensive and costly upgrades to your water system and natural gas line, electrical installation, and large-scale venting system to remove the smoke of gas-powered or propane tankless water heaters.

Tankless water heaters work by heating water with a metal element as the water passes through the compartment of the appliance. When you turn on your hot water tap, the water flows through a pipe into the tankless water heater where an electric element or gas burner heats the water to deliver an almost instantaneous supply of hot water whenever you need it.

Tankless Water Heater Types by the Power Source

There are different types of tankless water heaters including:

  • Electric
  • Natural gas, and
  • Propane tankless water heaters

The three types have similar operating mechanisms but different fuels. The type of tankless unit you choose depends on several factors such as the availability of fuel, household size, energy efficiency, initial and installation costs, the water temperature in your area, among others.
Tankless water heaters only heat incoming water when needed, effectively preventing standby heat loss. A tankless unit achieves this with the help of a heat exchanger.


Heat Exchanger

A heat exchanger is a device that transfers heat from one source to another to maintain a uniform temperature in a particular medium, in this case, water. The heat exchanger in tankless water heaters is the gas-powered burner in your gas tankless water heater or an element in an electric unit. Appliances such as a refrigerator and air conditioners also feature heat exchangers.

When you turn on the tankless water heater, a certain amount of water called the activation flow rate must pass through the unit before the heat exchanger is triggered. Once the heat exchanger is triggered, it heats the water to your preset temperature based on the water temperature in your area, and there you have your searing-hot water on demand to bath, wash dishes, clothes, and others.

Tankless water heaters can be point-of-use or whole-house heaters. Point-of-use units are smaller, less powerful, and more affordable. But they can only provide hot water for one or two outlets. The main advantage of this system is that it can be installed closer to the outlet, reducing heat loss due to lag time. Conversely, whole-house units are more powerful, larger, and more expensive but can supply hot water to multiple outlets simultaneously. Point-of-use systems are usually electric-powered while whole-house systems tend to be natural gas or propane-fired.

While tankless water heaters may be more energy-efficient than conventional tanked-type water heaters, they are also more expensive to buy, install, and operate. Tankless units may also require extensive and costly retrofitting of gas, water, or electrical installations if the current fixtures are not compatible with the model you bought. But they compensate with their compact designs, intelligent user interfaces, higher energy efficiency, longevity, and lower maintenance.

Common Types of Tankless Water Heaters and How They Work

how does a tankless water heater work diagram

There are typically three types of tankless water heaters; electric, gas, and propane-powered tankless water heaters. The three units have the same working principle but differ in the kind of fuel they use to raise the water temperature.

Tankless water heaters work by heating the water directly as it passes through the unit, rather than hold the water in a storage tank like the old units popularly used in the past. These units have heating elements in their compartments that heat cold water as it passes through the pipes, thus providing hot water on demand.
The downside is that these units cannot sustain a large volume of hot water output since they lack the infrastructure to hold that amount of water.

Because of their limited flow rate, it may not be possible to use tankless water heaters at multiple water outlets such as in the shower and the kitchen at the same time. If your household requires a large amount of hot water, you can install multiple tankless water heaters to serve different points of use

Since they don’t need to hold hot water in place for long periods, tankless water heaters can avoid standby heat losses that make storage water heaters less energy efficient.

In gas-powered tankless water heaters, a pilot light ignites the gas to heat the water while propane-powered units usually have battery-powered ignition systems. It is essential to keep the pilot light off when the unit is not in use to prevent energy loss in gas-powered tankless water heaters. A better option is to buy a unit with an intermittent ignition device.

Tankless Water Heater Buying Guide

Tankless water heaters have become popular as they help to cut energy costs, provide hot water on demand, and last longer than the conventional water heaters, which heat the water continuously even when not in use. Using the tankless water heaters can help reduce your energy bills by up to 35 percent, while also being environmentally friendly.best-tankless-water-heater

6 Features to Consider Before Purchasing a Tankless Water Heater

Before settling for a type of tankless water heater, there are numerous factors to consider to determine whether your choice is ideal for your household needs. They include the following:

  1. Flow Rate and Temperature Rise

    The flow rate is the amount of water the tankless water heater can accommodate while in operation, and it is measured in gallons per minute (GPM). Most units have a minimum activation flow rate and a maximum flow rate.

    • Minimum & Maximum Flow Rates
      The minimum flow rate is the minimum amount of water that must pass through the tankless water heater to activate the heating component. Conversely, the maximum flow rate is the highest volume of water that can flow through the unit while being heated.
    • Temperature Rise
      However, the flow rate depends on temperature rise. If you live in an area with moderate temperature where the water is already a little warm, the tankless water heater does not have to work hard to raise the temperature higher.
      Conversely, colder water will require the heater unit to work harder to bring the water temperature to the desired level, and this can impede the flow rate or even lead to cold water coming out of the tap.

    It’s best to determine your ideal temperature rise and required flow rate for the different points of use in your home. This way, it becomes easier to get a tankless water heater that can deliver the flow rate and temperature rise needed for constant hot water supply in your home.

  2. Source of Fuel

    According to the fuel used, there are three types of tankless water heaters namely electric, natural gas, and propane-powered. All of these have advantages and disadvantages, so you need to determine which is best for your circumstances.

    • Electric Tankless Water Heaters
      Electrically powered water heaters are the most energy-efficient but are more expensive to operate compared to natural gas or propane tankless water heaters. Also, electric tankless water heaters usually have lower flow rates compared to gas and propane units.
    • Gas Tankless Water Heaters
      Gas and propane units tend to have higher flow rates, and higher heating ability, but are usually bulkier than electric units.
      While electric units are easy to install and maintain, gas and propane tankless water heaters are expensive to buy and even costlier to install as they need ventilation to evacuate the exhaust of the gas.

    Depending on your needs regarding cost, space, efficiency, and maintenance, an electrical, gas or propane might be the ideal tankless water heater for you.

  3. Whole House or Point of Use?

    A point of use tankless water heater serves only one outlet at a time such as a shower or sink. If you want to use hot water simultaneously at different points in the home, a whole-house installation is better. Point of use tankless water heaters are smaller, cheaper and less powerful compared to whole house units. If your demand for hot water is low, a point of use unit is the best.

  4. Space

    If space is going to be an issue, electric units are smaller and more compact compared to propane and gas tankless water heaters. Some propane and natural gas units come in compact sizes for outdoor use, but their flow rate and heating power are limited.

  5. Installation Requirements

    Most manufacturers recommend installation by professionals to retain the warranty. The reality is that even if you want to DIY the installation, it is usually difficult and complicated with most tankless water heater units. If you want to buy an electric unit, your home’s electrical infrastructure must be compatible with the system. If it is not, then you have to carry out an expensive upgrade of electrical systems.

    The same applies to gas and propane-powered units that require combustion vents that may not exist in the home, leading to extensive and expensive installations. You also need to make sure the existing water outlets and inlets are compatible, and order replacements if what you have cannot work with your tankless water heater unit.

  6. Energy Efficiency

    Regarding energy efficiency, electric tankless water heaters trump gas and propane units. Electric tankless water heaters have an efficiency of about 98% while gas and propane-powered have between 80-85 percent energy efficiency.

    While an electric unit may require more electrical power, it raises the temperature of the water in less time, thus reducing energy bills. Also, electrical units are more environmentally friendly. But the cost of fuel in your area may be a determinant when choosing a high-efficiency water heater for your needs.

What Size Tankless Water Heater Do I Need?

Tankless water heaters are the rave of the moment among US homeowners. Despite its relative newness in these parts, the tankless water heater is not new; it only took a while to gain traction in the American market.

You will find several reviews online extolling the benefits of these efficient appliances over conventional water heaters. However, many homeowners are at a loss when they need to choose the required size tankless water heater.

Selecting the Right Size Tankless Water Heater in 3 Steps


How do you choose the best tankless water heater that will serve your household’s hot water needs conveniently? While a bigger sized tankless unit might be more expensive, the best you can do is choose a unit that can conveniently deliver the hot water output you need in your home. We discuss everything you need to select the perfect size tankless water heater in a step-by-step guide below.

  1. Step: Flow Rate

    Calculate the maximum number of faucets and appliances that will run hot water and the flow rate of each outlet. The flow rate is the number of gallons per minute (GPM) that flows through the hot water outlets in your home. Find the total of their flow rate to determine the ideal flow rate for your tankless water heater unit. For instance, you intend to use a showerhead with a flow rate of 2 gallons per minute and a dishwasher with a flow rate of 1.5 gallons per minute simultaneously.

    Manufacturers usually include the GPM rating of appliances with the model number tag. If some of your appliances do not have GPM ratings, you can determine the measurement with a gallon jug. Use the gallon jug to collect water from the appliance and calculate the time to fill up. If, for example, the faucet fills 1 jug in 30 seconds, that means it will fill two gallons in one minute and has a GPM rate of 2.

    Once you determine the GPM rate of all the appliances and hot water faucets you want to run on the demand water heater, add the values. Your tankless water heater should have a flow rate above your total water flow rate. For example, you need about 3.5 GPM if your total water flow rate is 3.35 GMP.

  2. Step: Temperature Rise

    Determine the temperature rise you need to get on-demand hot water. The temperature rise is the amount of heating required to raise the temperature of the incoming water to the desired hotness. This factor is important as it determines the energy consumption of your tankless water heater.

    Places with a warm climate often have higher water temperature, so the tankless unit will do less work to deliver hot water. However, regions with cold climates have colder water temperature, which means more heating to get the ideal hotness.
    To derive the temperature rise, deduct the incoming water temperature from the temperature of the water coming out of the hot water faucet.

    If you are uncertain of the incoming water temperature in your area, assume a low temperature of about 50°F, to avoid under-sizing your tankless water heater. Most people need their hot water to be 105-115°F, which means a tankless unit with a temperature rise of 55°F, assuming the incoming water temperature is 50°F.

  3. Step

    Let us look at a practical example. For instance, you want your 2.5 GPM shower head to deliver hot water of 120°F. If the incoming water temperature is 50°F, what is the desired temperature rise if you also want to run the shower and a 1.5 GPM kitchen sink at 110° simultaneously?

    For the above question, you need a tankless water heater that can raise the incoming water temperature from 50°F to 120°F. That means a tankless unit capable of providing a temperature rise of 70°F at 4 GPM. For this scenario, you need a tankless water heater that can deliver 4 gallons per minute at 120°F.

    Most gas-powered tankless units and many electric units can produce this level of output. Note that the water temperature may reduce if the outlet is a long distance from the heater. Bottom-line is to get a tankless water heater that can deliver the exact or more than your hot water requirements.


Choosing a Tankless Water Heater According to Your Needs

There are different tankless water heaters, depending on their power source and place of use. In this section, we talk about tankless units based on where to use them, and the features to consider while buying one. Regarding the location of use, there are four major types of tankless water heaters including:

  • Commercial tankless water heaters
  • Whole House tankless water heaters
  • RV tankless water heaters, and
  • Point of use tankless water heaters
  1. Commercial Tankless Water Heaters

    Commercial tankless water heaters are used in offices, restaurants, hotels, hospitals, and places with high human traffic. These types of tankless units offer enhanced energy efficiency and on-demand hot water supply, reducing a business’s energy bills and conserving water.

    As a business owner or manager who wants to buy a tankless unit for the office or business premises, you need to consider several factors while shopping for the tankless water heater. An ideal commercial tankless water heater should be capable of supplying upwards of 10 gallons per minute or more.

    Here are some features to consider before buying a commercial tankless unit.Commercial Tankless Water Heaters

    • True On-Demand Water Heater
      Before buying a tankless water heater unit, make sure it is a true on-demand water heater. People who use hot water on business premises don’t have time to wait until the water becomes hot. By getting a tankless unit that delivers hot water every time, you improve the experience of workers and clients who use your facility.
    • Energy Efficiency
      It is vital to buy an energy efficient commercial tankless unit because it will be used almost constantly, especially if your business receives high traffic.
    • Compact-Sized
      You want a tankless water heater that will occupy a small space in your building. Commercial space is expensive, so make the best use of every square inch.
    • Convenience
      It is advisable to buy a commercial tankless water heater easy to install and use. Extensive retrofitting will not only cost you precious cash flow but may also disrupt business activities.
  2. Whole House Tankless Water Heaters

    Whole house tankless water heaters are designed to deliver on-demand hot water to multiple outlets simultaneously. Such units can supply two showers, a kitchen sink, dishwasher, and wash-hand basin at the same time without delays. Whole house units are larger and have higher flow rates. But they also consume more energy.

    Homes with modest hot water needs will do well with one whole house tankless water heater. However, large households with several showerheads running at one time may require more than one tankless unit installed.

    • Energy Efficiency
      Since a whole house tankless water heater consumes a lot of energy, an energy-efficient unit will cut your heating bills and reduce waste.
    • Compact
      You should buy a compact-sized tankless unit to save space and prevent alterations to your property.
    • Ease of Installation
      Whole house tankless water heaters, particularly the gas-powered unit require venting and other extensive retrofitting that can increase the overall cost. Be sure to buy a unit easy to install and even easier to maintain.
    • Power Modulation
      Tankless water heaters with power modulation regulate performance based on hot water demand, saving energy costs.
    • Anti-Freeze Protection
      Anti-freeze protection ensures your unit does not become frozen during the chilly winter months. This is an important feature for externally installed outside of the home.
  3. Point-of-Use Tankless Water Heaters

    saving-energyPoint-of-use tankless units come are dedicated-use heaters installed to serve one water outlet such as a shower or faucet. These units are relatively smaller compared to a whole house and commercial units. If you live alone or do not need plenty of hot water, a point-of-use tankless water heater is an ideal choice. Point-of-use units are also less expensive, making them the most affordable tankless water heaters on the market.

    • Energy Efficiency
      You want a point-of-use unit with enhanced energy efficiency to reduce heating bills.
    • Compact Size
      One feature of point-of-use tankless water heaters is their small size as they are designed for installation in confined spaces. While shopping for this unit, buy a model that will fit into space where you intend to use it. It might be in your closet, underneath your kitchen or bathroom sink or any other space; always have the measurement of the installation site before going to the market.
    • Noise Level
      Ensure your point-of-use tankless unit runs silently, especially if you are installing the heater in a closet or somewhere around people. A silent tankless unit will allow you to enjoy your peace even while running at full blast.
  4. RV Tankless Water Heater

    An RV tankless water heater is installed on a recreational vehicle i.e., a house on wheels. The same features that apply to a small house apply to the RV tankless unit and more.

    • RV-Proofing
      The conditions in an RV differ from that of a house which is stationary. Make sure the RV tankless unit you buy can withstand the rigors of the road. An RV tankless water heater must be weatherproof and able to work smoothly when you are on the move.
    • Fuel Efficient
      RV tankless units use natural gas or propane. Since you will be on the road, get a model that delivers for longer with little fuel. When you are living the RV life, gas may be a luxury.
    • Anti-Freeze
      If your RV adventures will take you to cold regions, you need a tankless unit with anti-freeze so you can have a constant supply of hot water after your outdoor escapades.
    • Compact
      An RV is a small house on wheels and every inch has a purpose. Get a small tankless unit, preferably one you can install outside of the RV to save space, reduce load, and conserve fuel.

    Want to know how to buy an RV tankless water heater? Our helpful RV tankless water heater buying guide will tell you what to look for when it comes to selecting the best one.

Tankless Water Heater Maintenance Tips

Tankless water heaters are sophisticated equipment that requires regular maintenance. While tankless units can last up to 20 years, you may not derive maximum utility from investing in one if you don’t carry out maintenance when due. Not only will maintenance increase the unit‘s longevity, but it will also reduce repair costs, improve efficiency and cut energy costs drastically. So if you want your tankless unit to perform reliably and consistently through the years, maintain the unit according to the manufacturer’s recommendations.

How to Flush a Tankless Water Heater

It is necessary to flush a tankless water heater regularly as these systems are susceptible to mineral accumulation, lime scaling, and sedimentation, all of which can reduce the performance, efficiency, and longevity of the unit. Without regular flushing, your tankless water heater may not perform at peak performance, increase operating costs, and skyrocket maintenance fees. While most manufacturers recommend using a professional for this operation, it is a task you can DIY if you want to save cost.
But make sure flushing it yourself does not violate the manufacturer’s warranty. At least, you need to flush a tankless unit once in 12 months.

How you flush a tankless unit depends on the type of unit you own. While gas-fired and electric-powered units require regular flushing, different ways of flushing apply to them. Flushing generally helps to remove lime scaling and the effects of hard water on the system. Most manufacturers recommend vinegar for the operation as it is environmentally friendly, effective, cheap, and safe, although there are commercial solutions on the market.

Here are some points to note when flushing your tankless unit

  • Before attempting to flush a tankless water heater system, make sure to protect yourself against the hot water in the chamber if it was used shortly before that time.
  • Vinegar is the safest and most effective cleaning agent to flush mineral deposits out of your tankless unit. Avoid using chemicals for this procedure.
  • Consult your user’s manual for manufacturer’s instructions about flushing your unit.

Tips to Make Your Tankless Water Heater More Efficient

The following tips will show you how to maintain your water heater for efficient and hitch-free operation.
Before you start the maintenance process, unplug the power source, be it gas or electric to avoid accidents.
Turn off the water input and flush out the hot water before you proceed.

  1. Check Pressure Relief Valve

    Determine whether the pressure inside the tankless unit is above the recommended point. Release the pressure relief valve to reduce the pressure. Lift and release the PRV lever multiple times to check its condition. If the lever is working perfectly, it should return to the closed position easily. Be careful as the water in the pressure valve may be scalding.

  2. Check Vents

    Check for obstructions in the vents if you use a gas-powered tankless water heater. Also, inspect the pipes for cracks and damages. Make sure vent connections are screwed tight in place and gaskets in an excellent state.

  3. Combustion Chamber

    Inspect the combustion chamber, heat exchanger, motor, fan, and vents. Clean any debris, dust, or dirt that has accumulated in the combustion chamber. If you find broken or damaged parts, order for replacements.

  4. Ignition Check

    Clean the ignition rod with fine grit sandpaper until the surface is a bright finish. Also, clean the flame sensors but take care not to change the factory setting. The igniter might harbor small particles; dust these with a light cloth or blow off with a vacuum.

  5. Water Filter and Sensor

    Inspect the integrity of the water filter. The filter will most likely have mineral deposits, especially if the water in your area is hard. If the sediment reduces the filter’s movement, clean it off with lemon juice or vinegar. Otherwise, replace it. Also, check the flow sensor and clean carefully. The filter and flow sensor is essential to the tankless water heater’s efficiency, so make sure they are in top condition always.

  6. Check Flame Color

    If you are using a gas tankless unit, inspect the flame for any irregularity. The gas burner should burn a clean, stable, blue flame. If the flame is yellow, smoky, or unstable, then something is wrong with the gas burner. An inefficient gas burner will increase soot build-up and obstruct the heat exchanger.  Check gas spillage if the flame pattern is irregular.

Tankless Water Heater Brands of 2021

tankless water heater reviewsThere are several brands on the market, but some of them are clear market leaders. Below are the best tankless water heater brands.

Which Tankless Water Heater Brand is the Best?

Stiebel Eltron

  • Design
    For over 90 years, Stiebel has been a pioneer in the water heating industry. The company boasts an impressive array of compact tankless units with all the attention to detail in everything German.
  • Innovation
    Stiebel Eltron is a leader in innovation and technology. Its tankless units come with some of the most sophisticated sensors and intelligent functions that make using them a breeze.
  • Value
    When you buy a Stiebel Eltron tankless water unit, you are buying a system built to last. The company’s products are durable, efficient and worth the money.
  • Warranty

The company is confident in its products and offers a limited and extended warranty plan for its products.


  • Design
    Rinnai is an industry giant if you need high-efficiency indoor gas tankless water heaters. Over the years, the company has perfected its technology and now has some of the best tankless water heater designs on the market for residential and commercial use. Rinnai’s designs are compact and beautiful but you may need a professional for the installation.
  • Innovation
    As a forward-looking company in a highly competitive market, Rinnai needs to innovate. The company is one of the first to introduce a digital display on its tankless units and continues to add enhanced features to its products.
  • Value
    Rinnai focuses on adding value to the lives of its users. Whether for domestic or commercial purposes, Rinnai always delivers.
  • Warranty
    Rinnai offers limited warranties for its residential and commercial tankless water heaters. Be sure to read the terms and conditions.


  • Design
    EcoSmart tankless water heaters have a sleek, compact design that makes installation on a wall easy. The company’s tankless units are light and efficient.
  • Innovation
    EcoSmart leads the industry regarding green energy products and its proprietary Self Modulating technology delivers exceptional energy cuts compared to other brands. No wonder its products have an energy efficiency rating of 99.8 percent, almost perfect scores.
  • Value
    This brand has the interests of its customers at heart. The customer care is impressive and products are durable and long-lasting.
  • Warranty
    EcoSmart offers a limited lifetime warranty on all its tankless water heaters.


  • Design
    Rheem is a popular tankless water heater manufacturer that provides a wide range of electric and gas units. The company’s products are compact, top quality and reliable.
  • Innovation
    Rheem focuses on simplicity and ease of use. You won’t find complicated systems on their tankless units, making it easy for anybody to operate.
  • Value
    Like other brands on the list, Rheem offers exceptional value with its products and offer a variety of tankless units for residential and commercial users.


  • Design
    Takagi is a Japanese brand which provides top quality, high-efficiency tankless water heaters at affordable rates. The company offers some of the most powerful tankless units regarding flow rates.
  • Innovation
    Takagi does not come with frills but delivers efficiently. The company’s products can reduce your heating bills drastically due to their enhanced performance.
  • Value
    With a low price tag and high output, Takagi offers the best value for money in the tankless water heater market.
  • Warranty
    Takagi offers a limited warranty on its products. However, there are terms and conditions.
    The above brands offer an array of high-quality tankless water heaters for all your needs.  Whether you want a tankless unit for residential or commercial applications or live in a temperate or arctic region, these leading brands have something for you.


  • How Long Does a Tankless Water Heater Last?
    The tankless water heaters can last more than 20 years. Because they have a compact design, intelligent controls, and other enhanced features, they can perform for longer compared to water storage units.
    However, regular maintenance and inspection must be carried out to ensure the unit is always in good working condition. Tankless water heaters must be flushed regularly to remove lime scaling and mineral sedimentation that can reduce its efficiency and performance.
  • Do Tankless Water Heaters Save Money?
    Yes, tankless water heaters are more energy-efficient, reduce standby heat loss, and ultimately help you save up to 30-50 percent of energy bills on heating water.
  • How Much to Install Tankless Water Heaters?
    The cost of installing tankless water heaters depends on the type of fuel, and existing gas, water, or electrical infrastructure in the home. The installation cost for electric units can be up to $800 to $1500 while gas systems can cost between $1,000 to $1,500.
    Note that the cost can increase significantly if you need to retrofit the existing venting system for gas units or upgrade your electrical fixtures for electrical systems.


Tankless water heaters are the rave of the moment. These systems are safe, energy-efficient, environmentally friendly, smart, small and compact. Our water heater reviews covered the different types of tankless water heater systems, how they work, the pros and cons, and how to buy one of these units to enjoy maximum benefits.

While tankless units cost more initially compared to with water storage heaters, they cost more initially, compensate with higher energy efficiency, lower risk of water damage, compact design that facilitates flexibility of installation, and longevity.

Whether electric or gas-fired, the tankless water heaters can lower your energy bills, provide on-demand water and make your initial investment worth the while.

If you are considering a replacement for your conventional water heater unit, an electric or gas-powered tankless water heater is an excellent choice.