Buying a water heater? Consider condensing water heaters

Are you thinking about buying a water heater? Maybe you've heard that tankless condensing water heaters are the best option for you, but how do you know for sure? Is condensing worth it?

In this article, we look at the effect of water heaters on total energy consumption. We will also talk about condensing water heaters and if they are much different from the non-condensing variety.

Now, it’s hard to believe but, water heaters use about 17 percent of the total energy consumed in a home. This means that water heaters alone use up more energy than all other household appliances combined.

Yet, we can’t do without water heaters in the home, as they are an essential part of our lives. We need hot water for so many uses. For example, hot water is used for washing hands, showering, and doing dishes, among others. Therefore, it has become even more important to use efficient heaters to save on energy. Naturally, efficient heaters also leave a smaller footprint as they save on fuel and gas emissions.


What exactly are tankless and condensing water heaters?

Rinnai RUR199Rinnai RUR199

First of all, tankless heaters are devices that don’t store water in a tank. With heaters that have tanks, a whole lot of water is heated at once. The problem with this is that you’ve got this load of hot water which you might not need. So, this is not a very energy-efficient solution.

However, when you buy a tankless heater, you would only get the hot water you need. For one thing, the heater heats water as it is required and does not store any extra.

Secondly, when we’re talking about a tankless condensing water heater, we’re referring to heaters that are even more efficient or ultra-efficient. These heaters achieve added efficiency by extracting energy from the flue gases, using an extra heat exchanger, usually made of stainless steel. It then uses the energy to pre-heat the water that flows back into the heater. Therefore, with condensing heaters, very little energy is wasted. Some heaters, such as Navien NPE, heats the water close to 99% efficiency.

How does condensing work?

Well, without going too much into technicalities, a condensing water heater converts vapor into energy. Basically, when water is heated in a regular water heater, some of it is lost through vapor. A condensing heater like the Rinnai RUR98, during condensation inside the heater, releases the heat, which increases the temperature of the incoming water. Capturing the heat during the condensation process makes such heaters several times more energy-efficient than a regular non-condensing heater.

Condensing vs. non-condensing water heaters

Basically, both heaters serve one purpose, and that’s to heat water. While condensing water heaters like the Takagi T-H3 might have two commercial-grade heat exchangers, not so with non-condensing heaters. These water heaters have a single heat exchanger usually made of copper.

When the water vapor from the hot gases is cooled down, it turns into water. This process is known as condensation, which is acidic and corrosive.

In the case of the non-condensing water heaters, the temperature of flue gases is around 300 F, and due to its corrosive effect, they must use corrosion-resistant vents, such as stainless steel. Also, the thermal efficiency is about 80%, so 20% is wasted - released into the outside atmosphere.

The temperature of flue gases from the condensing heaters is much lower – around 100 F, so instead of using the expensive stainless steel vents, a standard PVC pipe is often utilized - a cheaper option that can also withstand the heat and acidic nature of the flue gases.

Tankless and condensing water heaters do not have water storage

Of course, we're talking about the tankless variety. An excellent example of a tankless condensing water heater is the Rinnai RUR98. This is an eco-friendly model from the Sensei SE+ series that comes equipped with lots of wonderful energy-efficient and advanced features.

For instance, it has a modulating gas valve that adjusts the power according to the set temperature and water flow. This means that it works perfectly whether you need hot water for one fixture or multiple applications. Due to its high water flow of close to 10 GPM, it can supply enough water for the entire house, where there’s a greater demand for hot water.

Also, the Rinnai RUR98 is a smart gas heater that comes Wi-Fi-ready and can be remotely controlled.

Another difference is the installation and running costs

To be fair, condensing water heaters cost more than non-condensing water heaters at first. If you’re going to buy a water heater, you should be prepared to spend more on the condensing type. A solid tankless condensing water heater like the Rheem RTGH-95, for example, costs close to $1500, while the non-condensing would cost less than $1000. As the venting is made of plastic, it is cheaper, plus the operational cost is lower due to increased efficiency.

Also, take into account the tax breaks and rebates from the utility companies, as the condensing heaters are Energy Star.

What to look for in condensing water heaters

Well, the most important thing to look for is the Energy Star Rating or energy efficiency. There are many tankless and tank-type water heaters out there, but the efficiency varies, from 0.57 for non-condensing tank-type to 0.96 found in Rinnai RUC98 condensing and tankless water heaters, for example. What you need to look out for is the heater that is Energy Star compliant such as the models mentioned in the above text.

Take the Takagi T-H3, for instance – this is an ultra-efficient and ultra-low NOx heater that is eco-friendly or "green." It makes use of a high-grade copper alloy that ensures the water heating is reliable. What’s more, it has in-built temperature controllers, and it complies with ultra-low NOx regulations. This is a versatile heater that’s perfect for larger homes and is Energy Star.

Therefore, it is clear that Energy Star gas tankless water heaters must meet the minimum standard for:

  •  Energy efficiency
  • Safety
  • Hot water delivery
  • Warranty period

Pros and cons of condensing water heaters

So, are condensing water heaters the answer to all problems? Obviously not. It is a fact that there will be advantages and disadvantages. Before you buy your tankless water heater, it will be a good idea to examine the pros and cons. Then, decide if this is the heater for you.


  • Higher energy efficiency
  • Reduced carbon footprint
  • Cost-saving
  • Safer for home use
  • Hot water on demand
  • Last longer


  • Expensive
  • More expensive to maintain (when they have a problem)
  • Corrosive acid in the condensate, which needs special treatment before it can be discharged into the drainage. A condensate neutralization kit will solve that problem
  • The hot water output in cold climates could be lower than what you need.
  • It might not be the best option for smaller homes/families.

Who should buy a condensing water heater?

To conclude, condensing water heaters are best for those who want to save and reduce their carbon footprint. The energy-efficiency nature of such water heaters like the Rinnai RUR98 or the Rheem RTGH-95 means they're an ideal choice either for a new or old home. 

The high energy efficiency makes them attractive purchases. They have a large capacity so they can quickly meet the high-water demand, are small and portable that utilize the smart control system, and include a diagnostics system, Wi-Fi, and Amazon Alexa voice recognition features. 

With their ability to regulate the flow of water, tankless condensing heaters are fast becoming a favorite. It does help when you can monitor the temperature settings. Also, when a heater can serve a small or large household without stress, then it is worth the purchase.

So, should you buy a condensing water heater? Well, if you are interested in cutting down on your energy cost and reducing your carbon footprints, then you should. Get in touch with us today to find out more about our recommended Energy Star tankless condensing water heaters.


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