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Rheem RTE 13 Electric Tankless Water Heater Review 2021

Rheem RTE 13

When it comes to picking the right heater available for you, you must consider multiple facts. In the field of the tankless heaters, the Rheem is indeed a top brand. Similarly, the Rheem RTE 13 has all the bases covered that make the product a top choice for you.

But before you buy any electronic product for your home, the first thing that you need to consider is a complete review of the product. Without knowing all the details, it may become tough for anyone to pick up the right product available for you.

Knowing all about the product is thus important. However, if you are looking for more about the product, here is a complete review of the Rheem RTE 13 that you can follow.

1. Rate of Flow

The Rheem RTE 13 comes with a decent speed of flow. Coming to the rate of flow technology, it seems to be smooth and quite fast. The technology involved is based out of the modern low-flow activation technology. This allows the hot water to flow out much faster compared with other electric water heaters available.

Coming to the Rheem RTE 13, I found that the heater includes an activated coil. This is around 0.4 GPM. Now when I compared all the other models available, I found that the heater works efficiently and quite better than most of the others available. So it efficiently works better than most others.

2. Rise of Temperature

Another important feature of the Rheem RTE 13 is the thermostat of the product. It can seamlessly rise to the optimum levels required. However, this mainly depends on the groundwater temperature that the heater is consuming.

So basically, the lower the ground temperature of the water is the rate of flow will be much lower. So it works highly when you have regular water temperature. The RTE 13 includes a regular temperature intake of 55 degrees and then produces an output of 105 degrees of water.

So it has a general water temperature rise of 50 degrees and because of this, the heater can approximately provide around 1.75 GPM with a regularity.

3. Durable

The one feature that always inspired me the most is all about the durability of the product. The RTE 13 includes decent interiors that can work well in any place. The most important thing is that all the components from the manufacturer are highly tested.

They come with quality materials that are great for a longer time. I tested the product with contaminated water for a long time. But I was surprised to see that the Rheem RTE-13 performed well. It has proper coating layers on the internal components that can prevent the heater from any type of corrosion.

4. Energy Factor

The energy factor of the product is another important part when it comes to the performance of the product. The energy factor depends on the conversion of heat and how much it is productive for your use. Most of the electric-based heaters come with lower efficiency than that of the gas-based heaters.

But when it comes to the energy factor, the Rheem RTE 13 always has a proper result. We found that the product has an energy efficiency of around 0.755 to 0.95 that works efficiently. Constantly, the water heater works around 0.82 that performs well as compared to others. You can always rely on the efficiency and low costs.

5. Technology

The Rheem RTE 13 comes with advanced technology to ensure that the flow of water is fast and effective. I found that the product comes with Rheem advanced technology when it comes to heating the water. This will get the proper rate of flow according to the requirements.

Apart from this, the power consumption is very low and it operates fast from 54 Ampere and it can always provide you with maximum results in the shortest period.


Coming to the performance of the Rheem RTE-13, it is always impressive for their use. When it comes to regular uses, it is always reliable for everyone. Moreover, it includes modern technology that can always be effective.

Comparing it with the other models, I found that the RTE 13 can easily save up at least 25% of the energy when you run it for longer hours. 

The product has a decent size and it an always provide a fast flow of hot water. The best part that I liked about the product is the option of low energy consumption. This tankless water heater is highly energy-efficient and it can work with low pressure providing faster results.

While I tried to use the product, I found that it took only a few seconds to heat up and get started. So even if you connect multiple faucets with the product, it works fast.


While coming to the warranty, the manufacturer always has a decent interaction policy. Overall, to check if the product is under warranty, you can go to the official website of the manufacturer and enter the serial number.

However, the body is well built and so are the internal components. The Rheem RTE 13 Warranty offers a 1-year warranty for the internal components. This is followed by a 10-year warranty on the heat exchanger. 

For any electric tankless heater, the offers by RTE-13 Warranty are quite impressive. However, there are certain criteria that you should be matched with to claim the warranty.

The water heater cannot be installed by any user and it must be done with the help of a licensed professional. Otherwise, the warranty will be null and void.


When you are looking at any electrical heater, the important thing that you must consider is the value of the product. It is evident that once you buy a product, it must have proper value in return. Coming to the Rheem RTE 13, it seems to be a little expensive when you first compare the price with other natural gas heaters.

However, because of the energy consumption and the low power operation, it seems to be a great buy in the long run. The one thing that has impressed me the most is the ability to provide proper hot water flow to any shower or a dishwasher simultaneously. It can be very helpful if you have a small family along with the product.

Apart from this, the electric tankless water heater comes with a longer warranty. So you may not have to worry much about the product performance. Even if there is any problem from the manufacturer’s end, the response is always good and you will get proper support from the technician. So you must follow the instructions set up by the manufacturer while operating the unit.

However, another factor that may determine the value is the output performance at the peak hour. If the water flow is regular and there is enough pressure on the faucet, the Rheem RTE-13 comes with a decent flow. You will not have any trouble while operating with the heater.

Installation & Design

Coming to the design of the product, the RTE 13 can ideally have a space-saving concept. When you buy any heater, you must take note of the space available on your wall. If you just want to mount it, make sure that nothing else and especially flammable objects are near to the heater.

However, it comes with a much compact unit. Since there is not any tank present, there is no spaced used for storage. The dimensions are around 7.25 x 7.25 x 7.25 inches.

Because of this compact size and nature of the product, it can be paired with any household appliances like showers, faucets or washing machines for your immediate needs. 

Coming to the installation of the Rheem RTE-13, this is another part that I liked. It comes in a 1 complete unit. So you do not have to assemble anything before installing.

Moreover, there is a wall mounting option available with brackets inside the package. So you can just install the brackets to the proper space just before you go to install the heater.

This tankless water heater weighs only 7.35 pounds which is much lighter than any of the products available in the market. So to lift the product is not a big deal. It hardly takes a few minutes to complete the entire setup and you may start using the heater in no time once it is ready.

However, there is one thing that you must keep in mind before installing the Rheem RTE-13. It is a warranty policy. The manufacturer clearly states that the warranty will be void if the product is not installed by any Rinnai Trained professional. So to install it, you need to take the help of any Rinnai trained professional.

The installation charges are not much and it is quite affordable. However, if you want to save up on the costs, you can ask your local plumber to do the installation or the plumbing requirements. Here, the installation charges will depend on the quantity of pipe that you need.


  1. It is fully electric
  2. The product can easily supply till 4 gallons per minute
  3. The size is highly compact and great for lifts
  4. You can get a 10-year warranty
  5. All the interior components are durable
  6. Rheem Tankless Water Heaters are easy to troubleshoot due to the display of error codes.


1. Heat Flow is low at times


The Rheem RTE 13 comes with a decent heating coil that can provide you a maximum of 4 Gallons per minute. But the rate of flow through the faucet depends on the water pressure that you have.

If you are living on the top floor of a multi-storied building, it is evident that the water pressure will be low here. You may not be able to get faster water. You can take the help of an external pump to make the rate of flow faster.

2. Maintenance required


Though the internal components of the RTE 13 are durable, they also have a single layer of protection. If you live in an area with a higher amount of contamination, sediments will be formed.

If you are not flushing the water heater, these sediments will get stuck and may cause erosion. The internal components are not so strong to evade any type of corrosion. So you must keep maintaining the product once in a while.

3. Startup takes time


The Rheem RTE 13 includes a Time delay service. So it takes time for the product to gear up. On average, you can consider the product to start providing hot water after 1 minute. However, this also depends on the locality. If you are living at places under extremely low temperatures, the groundwater is almost frozen.

Since there is no storage system to heat the entire water present, it will start providing just lukewarm water. So to get the best performance, you may have to wait for a little.

4. Difficult for large families


The Rheem RTE 13 comes with a decent flow of rate. However, it is not efficient for larger families. The heater may provide continuous hot water simultaneously to different faucets but not at the same time. It can provide hot water either to a shower or a dishwasher simultaneously.

So if you have a larger family, consider purchasing a different model. But if the family is only of 2-3 people, this Rheem water heater can be a decent purchase for you.

Frequently Asked Questions [FAQs]

Q1. How long can the Rheem RTE 13 last?

A1. Well, this is complete upto you… I have always kept on doing proper maintenance services to my RTE 13. So it has always helped me to easily run to a product. But you can still expect the heater to run for 15-17 years. Moreover, you can always get a 10-year warranty.

Q2. Do I need a ventilator with the Rheem RTE-13?

A2. Why would you even require it? Ventilators are used to emit the NOx out of the gas-based heaters. But this Rheem water heater is completely run by electric. So you can expect it to be environmentally friendly all the time.

Q3. What size wire is required for the Rheem RTE 13?

A3. Though I am not a professional plumber I had asked this question to them. Currently, they have installed 6 gauge wires on my home for the RTE-13. This seems to be working perfectly for my needs. I even checked out the status while turning on the AC and there seemed to be no problems.


Going through the complete review of the Rheem RTE 13 will surely help you to know all about the product. Comparing all the features and the performance, the Rheem RTE-13 seems to be a professional buy. The product includes some specific features that will always make it more professional to use.

We found the heater works precisely and efficiently to work regularly. So if you want to have the Rheem RTE 13 along with your needs, I think that it can always be a great buy.