Stiebel Eltron Tempra 24 Plus Electric Tankless Water Heater Review

By: John Owens,

Water Heater Expert

Overall Rating: 


Welcome to my review of the Stiebel Eltron Tempra 24 Plus electric tankless water. I hope I’m able to convince you in the end as to why I think this is the best tankless water heater on the market today. The Tempra 24 plus is an electric heater with a prime flow rate of 3.64 GPM at a temperature rise of 45°F. It can provide hot water for 2 showers and an appliance such as a washing machine simultaneously.

This meets the hot water needs of most homes in the country. This heater is ideal for a home with 3 bathrooms and family of 4 to 6 people. Provided there are no more than two people are showering at the same time, this unit is capable of meeting the hot water demands of larger families.

It can provide hot water for 2 showers and an appliance such as a washing machine simultaneously. This meets the hot water needs of most homes in the country. This heater is ideal for a home with 3 bathrooms and family of 4 to 6 people. Provided not more than two people are showering at the same time, larger families can also use this heater to meet their hot water demands.

If you live in a very cold climate where inlet water temperatures can be below freezing, the unit can only provide enough temperature rise for to sustain one shower at a time. So if you and your family can get by with taking showers sequentially during the winter months, then a single unit can meet your hot water needs in winter.

However, if you need to have two showers running simultaneously during the winter, you might need two of these units or buy the higher capacity  Tempra 36 Plus (click for best price) which can handle two simultaneous showers in the winter months. The Tempra 36 plus is just a little over $100 more expensive than the Tempra 24 plus.

Stiebel Eltron is a German brand with a proven track record of manufacturing high-quality, long-lasting tankless water heaters. And the Tempra 24 plus is no different.

The only negative I find with the Stiebel Eltron Tempra 24 is one that is peculiar to all tankless water heaters. It takes between 5 – 30 seconds for the hot water to reach the shower or sink depending on how far from the outlet the unit is installed.

Here is a flavor of what some REAL users have been saying about the Tempra 24 water heater.

customer review of Stiebel Eltron Tempra 24 tankless water heater

Stiebel Eltron Tempra 24 customer review

In my review of the best tankless water heaters, the Stiebel Eltron Tempra 24 rates very high. If you want a unit that can provide endless water heating for your home with precision temperature control, high-efficiency heating and long

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Key Features of The Stiebel Eltron Tempra 24 Plus

At this stage of my Tempra 24 Plus review, I want to touch on a few key features that make this unit so great.

Advanced flow control system: The unit features a temperature sensor that regulates the flow rate. Inlet water to the unit can vary in temperature during different times of the year. The unit automatically adjusts the flow rate to maintain your desired temperature.

The higher the inlet water temperature, the higher the flow rate at your preferred outlet temperature and vice versa. What this means is that if you set the temperature on the unit to 120°F, the unit will automatically adjust the flow rate to maintain a 120°F hot water temperature.

In practical terms, this means the hot water will come out of your shower at a higher pressure than in the winter. If the water pressure is too low for you, you might want to reduce your desired temperature to increase the flow rate.

Self Modulating Technology: This is a clever bit of technology that ensures that your unit only uses the least amount of energy required to heat the water.

Digital Display: The digital display tells you the precise temperature of water coming out of the tankless heating unit

Precision temperature control: The unit features a precision thermostatic control that allows you to set the temperature of the hot water to the precise temperature you desire in 1°F increments. You can choose a temperature between 86°F and 140°F. One thing I like about this unit is that you can set the temperature control knob to the off position. Let’s say you are away for a while and there is a leak in your home, the unit will not turn on automatically as it should and rack up a large bill in your absence.


Build Quality of the Tempra 24 Plus

The Tempra 24 Plus from Siebel Eltron is built with longevity in mind. The unit is built with the highest quality components to ensure the flow of hot water for many years. I have clients who have been using this unit for over 5 years with no problems. You only need to follow the prescribed maintenance to keep the unit running perfectly year after year.

The unit works in areas with hard water. However, hard water can lead to the build-up of scale in the unit and descaling is recommended as often as needed. For those living in an area with hard water, it is recommended that you purchase a flow aid system to flush and descale the system. I recommend J.C. Whitlam FLOW-KIT Flow-Aide System Descaler Kit for this purpose.


Installation Guide

Is it possible DIY install this unit? Yes ONLY if you know a thing or two about electricals. Installing this unit may require additional wiring and other electrical work that should only be done by someone who understands what they are doing.

If you know a thing about wiring and can handle the piping work, then it is possible to install this tankless water heater yourself in a couple of hours.  But the best option is to always get an installer to install the unit for you.


What is required to install the Stiebel Eltron Pentra 24 Plus tankless water heater?

It is recommended that your premise has a minimum of 150 amps. The Pentra 24 plus requires two (2) 50 amps circuits to handle the power requirement.  You need two 50 amps circuits because the Pentra 24 Plus is essentially two heating units built into one, with each requiring a 50 amps circuit.

Although it says 2 50 amps circuits, I usually install a 2 60 amps circuits for my clients.  You need to make sure that your home or premise meets these electrical requirements before installing the heater.

You need to make sure that your home or premise meets these electrical requirements before installing the heater.

You also need 6 gauge wires long enough to run from the unit to the fuse box twice to account for the two 50 amps fuses.

The unit should work with your existing plumbing. It uses 3/4 inch plumbing.  However, you might need 2 flexible connecting hoses to connect the unit to the outlet and inlet pipes.

You will need to purchase the two 50 or 60 amps fuse, wires and hoses separately. The unit comes with screws to mount it on the wall. If you decide to go the installer route, they should be able to supply everything needed to complete the installation.


Pricing Info

The cost of the Stiebel Eltron Pentra 24 Plus ranges from $700 to $1,200 depending on where you are buying it from (Click here to get today’s best price for this unit).

Installation costs (including labor costs) can range from $300 to $2,000 depending on the amount of work required. Resources such as and are great resources for finding installers with customer feedbacks.

After the initial cost, running costs for tankless water heaters are much lower than their traditional counterparts. The Pentra 24 plus has a 99.9% efficiency rating. You’ll notice a significant decrease in your monthly electricity and water bills which will offset your initial investment in the unit.


Pros and Cons


  • Lower running costs because of its 99.9% efficiency rating
  • An endless supply of hot water. You can take a six-hour shower without running out of hot water
  • It can meet the hot water needs of a 5 person family
  • Overheat protection protects you from accidentally scalding your skin.
  • A generous parts warranty
  • Ability to turn the unit off and prevent it from heating water if there is water leakage somewhere whiles you are away.
  • The unit is very quiet when running. You can barely hear it working.


  • If your power goes out mid-shower, you only have a few seconds of hot water left. However,  this is not a problem specific to the Pentra 24 Plus. It is the same problem for all-electric tankless water heaters.
  • Your home may require additional electrical work if it does not already meet the minimum requirements for installing the Stiebel Eltron Pentra 24 Plus in this review.


Bottom Line

The Stiebel Eltron Pentra 24 Plus is an excellent electric tankless water heater designed to meet the hot water needs of most homes and some commercial applications. You may want to find some reason not to buy it but there aren’t many. You may find a negative feedback or two but in my experience, these are sentiments that are not specific to this heater.

If you’ve got the money to invest in a tankless water heater, and this meets your hot water demands, then there really is no reason to buy this if you want to go the electric route. With its excellent performance, durable design and easy to use interface, it is easy to see why it has an almost perfect rating by users. That is why I placed it in prime position on my list of reviews of the best tankless water heaters

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Tips to get the best out of your Tempra 24 Plus.

  • Install the unit as close to the showers or sinks as possible. The closer it is, the quicker the hot water gets to the shower or sink.
  • Instead of getting a Tempra 36 plus, you can choose to go with a Tempra 24 Plus combined with a Tempra 12. The Tempra 12 will act as a pre-heater. This will raise the temperature of the water entering the Tempra 24 Plus, ensuring that you get a higher flow rate at high-temperature rises. This will be a great set up for those living in colder climates.