In today’s time, convenience and efficiency are essential to keep work simple, especially when it comes to everyday tasks like heating water. One of the best choices is the under-sink tankless water heaters. They are great for being a compact and energy-efficient solution for providing hot water exactly where people need it. In particular, under-sink tankless water heaters are helpful in the kitchen because they deliver hot water on demand while saving space and energy. So, if you don’t like washing dishes with cold water, you can get the job done thanks to this compact heater.
Similarly, tankless under-sink water heaters are also an excellent choice for bathrooms and other areas with limited space. Due to their diminutive design, they can be installed in tight locations. Therefore, they won’t ruin your interior. Nevertheless, they can work efficiently because they can connect to a mains water supply. Hence, they can deliver direct heat at high pressure and nice, warm water.
Impressed with the under-sink tankless water heaters? Then, you are in the right guide because we will explore the best picks available on the market, helping you buy a high-quality under-sink tankless water heater for your home or business.
What is an Under-sink Tankless Water Heater All About?
As their name implies, under-sink water heaters are designed to be installed beneath a basin to provide instantaneous hot water. Thanks to their compact size, they are handy when hot water is needed. As for how they function, heaters can heat the water as it travels through or warm up a tiny quantity. Ultimately, the under-sink tankless water heaters are a great solution for supplying hot water quickly without having to wait for it to travel from a central water heater to the sink.
Different Types of Under-sink Water Heaters
There are two different types of under-sink water heaters. Explore them below.
Storage or Tank Under-Sink Water Heaters
Storage or tank under-sink water heaters work similarly to traditional home water heaters. They look exactly like their name — they consist of a tank that stores a certain amount of hot water and keeps it heated to a set temperature until it’s needed.
Generally, these types of water heaters are relatively simple to install and provide a steady hot water supply. However, the amount of hot water available is limited to the capacity of the tank. This means that you will need to wait once the stored hot water is depleted.
Tankless or Instant Under-Sink Water Heaters
Tankless or instant under-sink water heaters do not have a storage tank. Instead of storing a hot water supply, they simply heat water on demand as it passes through the unit. When you turn on the hot water faucet, cold water flows through a heating element or coil inside the unit, rapidly heating it to the desired temperature before it reaches the faucet.
These models are more energy-efficient than storage or tank under-sink water heaters because they only heat water as needed. They eliminate standby heat loss associated with keeping a tank of water continuously hot. If you want an endless supply of hot water, this model is for you.
Top Picks for the Best Under-sink Tankless Water Heater Models
Among the array of options available, under-sink tankless water heaters stand out as a space-saving and energy-efficient solution. These compact marvels provide instant access to hot water precisely where it’s needed. If you want to buy one, here is a list of the top picks for the best under-sink tankless water heater models you can choose from:
The Rinnai RL75iN is an exceptional choice for those seeking a gas-powered tankless under-sink water heater, especially prioritizing energy efficiency. This model proves particularly advantageous when installation space is at a premium, such as in tight areas like crawl spaces or attics. In regions where groundwater temperatures typically range between 47°F and 67°F, the RL75iN boasts a commendable capacity to deliver a high discharge rate of heated water, capable of servicing up to 5 units simultaneously.
Moreover, this under-sink tankless water heater offers additional functionalities, including the option to connect to a Wi-Fi system, enhancing accessibility and ease of monitoring. However, it’s important to note that for seamless integration with a Wi-Fi system, an additional regulatory piece must be purchased separately.
PROS
It can be installed in a cellar, crawl space, or attic
An under-sink tankless water heater offers a blend of efficiency and convenience, and among the available options, the Rheem tankless water heater stands out for its user-friendly design. This model simplifies temperature adjustments with a streamlined control lever located on the unit’s front, allowing for precise adjustments in 1-degree increments. Additionally, its digital display feature provides clear confirmation of the set temperature, ensuring accuracy. Users have the flexibility to modify the desired temperature at any time, enhancing control and comfort.
With a maximum discharge rate of 3.51 gallons per minute (GPM), this under-sink tankless water heater is compact and versatile, suitable for point-of-use applications. Due to its space-saving design, it can also be installed in alternative locations such as a cellar or attic. However, it’s important to note that this unit is susceptible to frost damage and should not be installed in areas where temperatures may drop below zero, ensuring optimal performance and longevity.
Wouldn’t it be fantastic to have an under-sink tankless water heater that not only delivers hot water on demand but also significantly reduces your energy bill? The Atmor 13kw/240v, 2.25 GPM Tankless Water Heater fits the bill perfectly. With this innovative unit, you can save up to 30% on your energy expenses. Unlike traditional water heaters, this tankless under-sink water heater activates only when it detects water flow, minimizing electricity consumption when not in use.
In addition to its energy-saving benefits, the Atmor tankless water heater features a compact and lightweight design, making it versatile for installation options such as on the floor, wall, or under the sink. Its adaptability extends to various applications, from kitchen sinks to showers, depending on the warmth of the incoming water. Capable of raising the temperature of 2.5 liters of water per minute by 45 degrees, it ensures a comfortable and consistent flow of hot water.
PROS
Three modes of electricity.
It can be used in the restroom
Easy to install.
Small and light in weight.
Energy saving.
CONS
It lacks scorching protection despite its dire need for it.
While this tankless water heater boasts a compact and affordable design, it doesn’t compromise on features compared to its pricier counterparts. With a power rating of 13 kilowatts, this electric tankless water heater efficiently supplies heated water to standard kitchen or bathroom fixtures. Its on-demand heating system not only ensures cost-effectiveness but also eliminates the need to maintain a reservoir of hot water.
Moreover, this under-sink tankless water heater stands out for its ability to deliver hot water swiftly and reliably while significantly reducing energy consumption by approximately 60%. Thanks to its self-regulating automation, the unit optimizes power output, further enhancing efficiency. EcoSmart provides assurance on the lifespan of the electronics and exchanger of this model, reinforcing its reliability, especially when installed by a professional or licensed electrician.
It’s worth noting that this under-sink tankless water heater is suitable for areas with water temperatures above 67 degrees Fahrenheit, ensuring optimal performance in various environments.
PROS
Has a 90% reduced footprint than conventional tank heaters
Includes sophisticated self-modulating technology that utilizes only the energy required to heat the water.
Provides limitless hot water on demand at regulated flow rates
CONS
Unable to heat sufficient water for larger residences
The warranty excludes labor costs and accidental damage.
All tankless water heaters promise energy savings, and the Stiebel Eltron Tempra 36 Plus is among the most energy-efficient models available. Notably, Energy Star does not issue energy factor ratings for electric tankless water heaters, according to the manufacturer. The Tempra 36 Plus provides up to 7.5 gallons per minute (GPM) of hot water, ample for three or more fixtures, all while operating with minimal noise.
Unlike some under-sink tankless water heaters susceptible to temperature fluctuations when multiple faucets are in use, the Tempra 36 Plus features advanced flow control. This innovative technology subtly reduces water flow if hot water demand spikes, effectively preventing the dreaded “cold water sandwich” phenomenon. Consequently, users can expect consistent output temperatures without sudden drops in warmth when turning on additional faucets.
Moreover, addressing a common complaint about rapid water heating in under-sink tankless water heaters, the Tempra 36 Plus offers one of the lowest temperature thresholds among tankless models. With a minimum 68 degrees Fahrenheit, it ensures a comfortable and gradual increase in water temperature, enhancing user satisfaction and safety.
PROS
Extremely silent operation
Minimum 68 degrees F
Maintains constant temperature discharge
99 percent energy effective
CONS
Requires 300-volt electrical service
Comparison of the five best under-sink tankless water heater
Product Wattage Temperature Range Flow Rate
Comparison of 5 Best Under-sink Tankless Water Heaters
PRODUCT
WATTAGE
TEMPERATURE RANGE
FLOW RATE
Rinnai RL75iN Water Heater
Gas-powered
47°F to 67°F
7.5 GPM
The Rheem 18kW Tankless Electric Water Heater
18kW
1-degree increment
3.51 GPM
Atmor Tankless Water Heater
13kW
45° and above
2.25GPM
EcoSmart ECO 11 tankless water heater
13kw
67°F and up
1.3-3.1 GPM
Stiebel Eltron Tempra 36 Plus Tankless Water Heater
3600 watts
Minimum 68 degrees F
7.5 GPM
FAQs
Are there code requirements and safety matters I should consider in under-sink tankless water heaters?
Yes. Under-sink tankless water heaters are complex appliances, and although most manufacturers provide detailed installation instructions, we strongly advise having a professional install your new unit. This is a wise investment. Hiring a professional plumber will ensure you comply with all local building code requirements. In addition, many manufacturers require professional installation to activate the warranty.
Why is it crucial to purchase the proper size tankless water heater?
It’s crucial to purchase the proper size tankless water heater to ensure that it meets your household’s hot water demand efficiently. If the unit is too small, it may struggle to provide an adequate supply of hot water, leading to discomfort and inconvenience. Conversely, an oversized unit can result in unnecessary energy consumption and increased costs without delivering any additional benefits, making it essential to match the heater’s capacity to your specific usage requirements.
Can I fix my tankless water heater under the sink?
Even for experienced do-it-yourselfers, installing a tankless under-sink water heater is a VERY DIFFICULT and POTENTIALLY DANGEROUS task. In many scenarios, doing so is prohibited by the local plumbing code and may void the warranty. Plus, installation required proper electrical configuration for safety and optimal performance. So it is not a job for everyone. Unless you replace a gas-powered tank water heater, you will need gas lines installed and possibly a gas meter upgrade.
Why is the installation of tankless under-sink water heaters so expensive?
Under-sink tankless water heaters have a higher initial cost than tank heaters, ranging from $1,200 to $3,500 for residences. New gas and water lines are needed for installation, necessitating a more labor-intensive setup. For tankless electric water heaters, new electrical wiring must be installed, and that adds to the cost.
How can I determine the size of a tankless water heater I need?
To know the right size of tankless water heater you need, consider factors such as the number of fixtures (sinks, showers, etc.) in your home, the flow rate (in gallons per minute) of each fixture, and the temperature rise needed to reach your desired hot water temperature.
Conclusion
In conclusion, selecting the right under-sink tankless water heater can significantly enhance your home’s convenience, energy efficiency, and overall comfort. After exploring the top five options available, it’s obvious that each model offers unique features and benefits tailored to various household needs. Whether you prioritize energy savings, compact design, or advanced technology, there’s a tankless water heater on our list to suit your preferences.
Hopefully, you have seen this guide as a helpful solution in finding the best under-sink tankless water heater that suits your home. Remember, our team is always available to help you if you require professional guidance on the perfect system or if you’re ready to have your new water heater installed.
Hi everyone! My name is Jason, and I am the founder of HeaterWise.com. Having run my own business as a Heating Engineer for 21 years, I have picked up a few things along the way.
I wanted to create Heater Wise as a place where anyone could come, from far and wide, to find the information that they need.
I hope you will join us here at Heater Wise, to get started on your own journey, to expand your knowledge, and make the best heating choices for you and your family.
