Tankless Water Heater Brands: The Complete Buyers Guide

Tankless water heaters or demand-type water heaters are an energy efficient way of generating hot water in your household. Their instantaneous systems provide hot water only as needed, as opposed to tank systems that heat a large amount of water, regardless of how much you need. Often seen as a more energy efficient method, if you are looking to switch to a tankless water heater, here are some things to consider and a quick guide to the brand you will be looking at.

What to Look for in a Tankless Water Heater Brand

If you are switching to a tankless water heater, make sure to bear the following considerations in mind.

Fuel type

When you’re looking for a brand of tankless water heaters, you want to ensure that the brand makes a heater that suits the fuel type you’re looking for. Two things are important to consider here. Firstly, which types of fuel do you have available in your home? While both natural gas and electricity are widely available in the United States, not all homes have the capacity for both. In the first instance, it is usually best to choose the type of fuel you have available to you, otherwise, you may face high installation costs to implement a whole new system.

Secondly, you want to consider the cost of running these systems, especially if you do have more than one fuel type available to you. You can run your tankless water heater on propane, natural gas, or electricity, but natural gas is generally the cheapest and cleanest type of fuel. That said, electric showers tend to use less water and therefore can have lower running costs.

GPM and Size

Sizing Guide (Source)

Think about the flow rate and size of the unit. Not all tankless water heaters can deal with the same demand for hot water. While some bigger models and brands are able to produce large quantities of hot water to a whole house, others are designed to work with smaller applications, such as a single sink or shower. With this in mind, consider how you’ll be using your water heater. If you want to be able to use it with various appliances at once, look for brands that offer bigger water heaters with a high flow rate or high gallons per minute (GPM) water heaters that can serve the whole house. If, however, you want a water heater for an outside sink or a garage shower, you may just want a smaller unit with a low GPM water heater.

Energy Efficiency

Consider the energy efficiency of your water heater unit. If the energy efficiency is low, you will find yourself paying high power bills each month. You want to look for the Universal Efficiency Factor (UEF). The higher the number, the more efficient the system is, which represents how much of the energy is transferred into heat energy.

For gas water heaters only, you can look for the Energy Star. This is a seal that demonstrates that a particular model or brand of water heater is exceptionally efficient. It is measured by five criteria: flow rate, efficiency, size, fuel, and the warranty.


It is easy to get fooled into thinking that large, well-known brands supply the best water heaters that are durable and live a long life while producing consistent service through their lifetime. However, it is not uncommon to find that some bigger brands don’t have the reliability necessary and would rather continuously replace a product that improves its longevity. As a customer, this would mean constantly reinstalling a product.

To look for a reliable brand, try to look at customer ratings. Take into account the durability or the product and its longevity, as well as the levels of customer service that buyers experience. Try to find brands that are in excess of 4 out of 5 stars.


While you may find your ideal tankless water heater online, think about what happens if it breaks down. Sometimes you may have to find parts or someone who can service your unit. While you can sometimes call a service person from the brand manufacturer, this doesn't happen all the times, which can often be expensive.

Before purchasing a water heater, consider if these are offered in your local area and whether someone in your near vicinity can help you if you need a repair.


With all this in mind, the price can also be a determining factor. Unfortunately, the price of tankless water heaters does not always denote the quality. While cheaper models may save on upfront costs, usually they are less durable and need replacing sooner, while also being less energy efficient, increasing the running costs.

That said, more expensive products may also not be ideal for you. Expensive water heaters tend to be larger in size with higher flow rates. If this is not what you need, your money is going to waste. Always compare the price with the other factors and consider what you need first, as your application will determine whether the unit is of value or out of your price range.

A Look at the Key Brands 

Take a look at some of these brands offering high quality tankless water heaters. Each specializing in different ways, these brands offer top products with good added extras.


A German company that started in Stuttgart in 1886, Bosch is a leader in a variety of technologies, from the automotive industry to industrial technology. Bosch now has factories and branches worldwide, with a particular dedication to improving everyday life with innovative technology.

They are known for their thermotechnology and provide sound water heater units that have a long life and work very efficiently. Bosch has a special focus on environmental stewardship and preserving the planet. In this sense, they have made it their aim to develop ultra-efficient products to reduce the fuel consumption, including their tankless water heaters. Both models of tankless water heaters, the Therm and Greentherm have up to 98% efficiency, making them super efficient compared to competitive models. Their condensing models are more efficient than their non-condensing models, but all of them are compact in size, making them ideal to fit into a residential sized space.

Bosch has dedicated their time to producing energy efficient products that fit together to fall in line with the idea of a smart home. Their concept is to provide a series of integrated systems in the home that are easy-to-install, use and maintain. For this reason, Bosch is one of the best brands for cutting-edge technology and innovation.

Stiebel Eltron

Founded in Berlin, Germany, in 1924, Stiebel Eltron is a very trusted brand with a focus toward customer care and service. They have a mission to provide products that are energy efficient, extremely safe, and that provide comfort to the user.

In terms of energy efficiency, all of their products are highly insulated in order to prevent loss of heat while in use. However, their energy efficiency does not compromise their performance, as each tankless water heater includes smart microprocessor technology to enable a steady rate of flow no matter whether the demand varies on the water heater.

As Stiebel Eltron focuses on customer comfort, they have a varying range of sized water heaters in order to make sure you have the correct size for your home. Easy to figure out and install, their range is user-friendly and enables you to have the most efficient unit for your usage pattern. When it comes to installation, because they are small in size, they can be stored closer to the water source and do not cause a disturbance in the house. They have a long lifespan as hot water is not being stored within them and because the unit automatically sensors water temperature of incoming water and adjusts according to this.


EcoSmart specializes in designing high-quality environmentally-friendly products. Unlike other manufacturers with diverse ranges, EcoSmart only makes tankless water heaters as they feel these are more environmentally-friendly and energy efficient than older models, such as stored hot water tanks. They offer both gas and electric tankless water heaters, as well as condensing water heaters.

EcoSmart has a patented technology incorporated in all their models called Self-Modulating Technology. Each model is equipped with a flow sensor that monitors the demand on the water heater. This modulates the energy consumption to the demand on the water heater, which results in up to 50% savings on your water heating bills.

As EcoSmart focus on energy efficiency and savings, they aim to make it as easy as possible for customers to save energy when using their water heater. Each model is fitted with a digital display which makes it simple to lower the temperature and save energy.

The heaters are also designed to be easily maintained and serviced. For example, if the element burns out, the whole unit must usually be removed and replaced. With EcoSmart models, the element is easy to unscrew and replace, making the whole process user-friendly and making EcoSmart one of the most eco-friendly and waste reductive brands.


Established in 1988, Eemax started out as a line of commercial water heating products. In 2000, they expanded into producing residential products. They are now part of the same family as Rheem and EcoSmart, a large Japanese company called Paloma Group. Eemax is definitely not as well known as some of the other brands on the market as they entered the market somewhat later than their counterparts.

However, despite a late arrival, Eemax offers some of the most durable tankless water heaters out there. They tend to last well over 20 years while being far cheaper than many of the other products offered by the competition.

Their tankless water heaters are also hugely energy efficient. They tend to have an energy efficiency rating of 99% which puts them ahead of many of the big brands, as they only lose 1% of their energy when converting it to heat.

In terms of being user-friendly, Eemax products are easy-to-install. They are compact and able to fit into small spaces, meaning you don’t need to find a separate storage space for them. Not only that, they work on low-pressure water so you don’t need to install any complicated parts to get Eemax water heaters going. With low prices, high efficiency, great durability, and user-friendly installation, Eemax offers a lot to rival with its long-standing competition.


One of the newest brands by far, Eccotemp was founded in South Carolina in 2004 as a family business. They have a strong belief in family values and focus on trying to find solutions to keep all family homes comfortable and energy efficient while spreading the message of being ecologically conscious. Not only do they provide a diverse range of propane, gas, and electric tankless water heater for the home, they are the number one supplier of portable tankless water heaters.

Eccotemp products are very durable due to the forward-thinking technologies installed in the products. For example, all outdoor models come with an anti-freeze technology to help prevent a shut-down in the colder months. The water heaters are also installed with ventilation systems and a powerful fan to cool down the heaters, preventing them from degrading or breaking.

As Eccotemp wants to provide their clients with the best option for their home, their range of tankless water heaters is extensive. You’ll find different fuel types, installation types, applications and so on to suit whatever application you need in your home or on the go. Eccotemp clearly has the customer in mind and proves itself as a customer-friendly supplier at every turn.


The largest manufacturer of water heating devices in the USA, Rheem was founded in California in 1928. Having won a myriad of awards for their energy efficiency measures and forward-thinking designs, Rheem is a household favorite across the country. They are now part of the Paloma Group in Japan and sit as a subsidiary with other brands like Ruud and EcoSmart.

Rheem offers high efficiency condensing tanks with efficiency ratings of up to 96%. Their models can be fuelled by gas or electricity, and all come with electric controls to help monitor the temperature more effectively, to harness the energy efficiency of the unit.

One notable thing about Rheem tankless water heaters is the performance value. Their products are highly rated for providing a consistent temperature even when they have a high demand for them. The Hot Start Programming prevents a fluctuation in the temperature while the unit is working, while most of their water heaters tend to have very high flow rates. In this sense, they work well in households with multiple bathrooms and hot water appliances.

One downside to Rheem products is that they generally have a higher price tag than their competitors. Despite this, they have a great warranty, and their customer service is very highly praised, making them a worthwhile investment.


A tankless water heater could be your first step toward a more energy efficient home. Aside from being more ecologically friendly, tankless water heaters tend to save you money, while also being a little easier to install. The prices of different brands can vary wildly, and this is usually due to their reputation and service. Always make sure to consider customer reviews before taking the plunge.

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