These low flow 120-110 volt tankless water heater choices are great for a single hand washing sink.
Also, I have provided one 110 volt tankless heated shower product that is suitable for use in the far southern U.S.
Introduction To Picking The Best 120-110 Volt Tankless Water Heater
With so many different models of tankless water heaters being available on the market, it becomes very tricky to select the one that will be most suitable for your specific requirements.
To make matters even more complicated, the different models each have their own set of features which may or may not be required for what you want to use it for.
It should be noted that the products discussed in this article are the best in the 110-120 volt category. To get anything better you must go to a 220 or 240 volt system (future article) or a natural gas/propane system (future article).
Tankless Water Heater Selection Criteria
When selecting a tankless water heater, one of the first specifications you need to look at is the maximum flowrate measured in gallons per minute (GPM). The table below shows the average GPM used by different applications.
Knowing the maximum flowrate required is in itself, however, not enough.The maximum flow rate can be misleading, because the flow rate is lowered by how cold the groundwater temperature is.
Tankless water heaters heat the groundwater and should ideally raise it up to at least 105 degrees. Which is considered to be hot by most people.
The problem is that the average groundwater temperature differs depending on where in the USA you are. The map shown below will give you a good indication of the ground water temperature in your area.
The products selected for this review will work in most of, or all of the USA, because they have enough power to raise the groundwater temperature. You may however only get .4 GPM instead of .5 GPM in the far north.
The farther south you live, the warmer the groundwater. So, you can get higher temperatures than 105 degrees, or more water flow. This might make specific heaters useful for a kitchen sink instead of just a bathroom sink.
Criteria Used for Including or Excluding Products in This Review
Most 110-120 Volt tankless heaters are only useful for washing hands in a sink because they only provide a maximum .5 GPM hot water (105 degrees) flow. All models in this group can get more water flow if the incoming water temperature is higher.
The first product listed can be used in warmer climates with a water saving showerhead, because it has a maximum 2 GPM.
Generally, the products listed are only suited for one faucet. If you try running another faucet, the one farthest from the heater will get less hot water. Or if one faucet has a .5 GPM flow aerator and the other one has a standard 1.5 to 2.0 GPM aerator, the 1.5 to 2.0 GPM aerator faucet will have colder water, because of greater water flow.
It should be noted that 110 volt devices can work with a 120 volt system and vice versa, because the devices are made to work within a plus or minus 10% voltage range. However, selecting a heater that works at 120 volts is generally better than one that is designed for 110 volts.
There are tankless heaters available on the market that come with a plug-in cord and can operate on your current house wiring (120 volts). Although these devices are less expensive and lower powered, they have not been included in the list, because they are only useful when the incoming water is already warm, i.e. on the south coast of the USA.
The devices in this list all need a dedicated circuit breaker and upgraded wire size to operate.
Many of the products require (and include) a 0.5 GPM sink faucet aerator. It restricts the amount of water that can flow out of the faucet so that the device has enough time to fully heat the water.
Modulated vs Unmodulated Water Heating
Unmodulated water temperature devices will heat until they hit their highest temperature or the temperature set point that was selected, and then turn off. Which means that you will now have cooler water until it turns back on again.
With unmodulated devices, if the water is too hot, you can cool it down by turning on the cold water, or by turning up the hot water volume past the .5 GPM flow rate (if a flow restricting faucet aerator isn’t used). Which means that the water doesn’t spend enough time in the heater to reach its maximum temperature.
Less expensive devices that do modulate to a certain extent, do so by turning on one or more heating units. The best (fully modulating) modulating units use a computer chip to modulate (60 times every second) the amount of heat the unit makes according to incoming water temperature, water pressure, and water flow. This is what many customers think they are getting when the device lets them set a temperature, but that isn’t always true.
Many devices that let you set a temperature are just activating the number of heating modules used – which is a “rough” form of modulation. This rough form of modulation can be effective in very warm climates (warm groundwater temperatures) where the unit can produce more than the .5 GPM it is rated for.
There are only 3 products in this list that actually fully modulates the heater in response to varying incoming water temperature, changing water pressure (someone using cold water somewhere else in the house), and the amount of water flow being used. These are the iHeat HS-4 Electric Tankless Water Heater, the Stiebel Eltron DHC 3-1 and the Chronomite SR-30L/120 HTR SR Series
Flushing Air From The Water Heater
A big reason for heaters to never work right from the start, or just after installation, is that not all of the air was flushed out of the heater before turning the heater on.
If there is any air in the heater, it will over heat and either trip the overheat safety feature (many heaters don’t have a safety system), or it will burn up some part of the system inside the heater.
After tightening all fittings at the water heater, but before switching the power on, turn on several hot water faucets and let the water to run though the water heater. About 3-4 minutes should be enough time. This process purges all the air from the water lines and MUST be performed prior to turning on the power at the unit.
Note: Failure to follow this step can cause permanent damage to the heating elements.
When a water heater or the plumbing system in a home is maintained, this could result in air being introduced into the plumbing. Before powering the unit up after such maintenance, it’s important to first turn the water heater off and purge the lines from any air.
Water Quality Is Important To Your 110 Volt Tankless Water Heater
Poor water quality can damage heaters from hard water scale deposits, sediment clogging aerator screens, and other factors.
Water quality can have an impact on appliance longevity and may not be covered under the manufacturer’s warranty.
For water analysis data, call your local water department, or if on a well, have well water analyzed periodically. If water quality exceeds one or more of the values specified below, it is recommended that you consult a local water treatment professional for water softening/conditioning options.
The first three factors to evaluate are the pH, the total dissolved solids (TDS) and the total hardness. The pH should be between 6.5 and 8.5, the TDS should be less than 500 mg/l, while the total hardness should be less than 6 grains, or 100 mg/l.
The presence of various chemical elements should also be limited. These are as follows:
- Chlorides – Less than 250 mg/l
- Aluminum – Less than 2 mg/l
- Iron – Less than 0.3 mg/l
- Copper – Less than 1 mg/l
- Zinc – Less than 5 mg/l
- Manganese – Less than 0.05 mg/l
There are many water filters and water softening products available on the market for users of tankless water heaters.
When installing a tankless water heater, always follow the manufacturer’s instructions for optimal results and to ensure that your water heater will not only operate as expected, but also to ensure that you don’t invalidate the manufacturer’s warranty.
Some manufacturers specify that their product must be installed by a professional installer, and also specify which installation codes should be adhered to.
We recommend that a manual shut-off valve (ball valve) is installed before and after the water heater so that there is an easy way to shut off the water system. That will make future maintenance or servicing much easier.
Winterizing Your Tankless Water Heater To Prevent Freeze Damage
It should be noted that the installation manual of several models state that the water heater must not be installed in a location where it may be exposed to freezing temperatures.
Also note that:
- Freeze damage is not covered under the warranty.
- Use of agents like anti-freeze are not allowed as they may cause damage to the water heater’s internal components.
If the heater must be left in a space that is likely to experience freezing temperatures, all water must be drained from the heater.
Due to the shape of the heat exchangers and connecting pipe, it is extremely difficult to get all of the water out of the heater. Follow the procedure below to best minimize the chance of freezing:
- Disconnect electric supply.
- Disconnect cold and hot water pipes from fittings on bottom of heater. Allow water to drain out (have a catch basin ready).
- After allowing all water to drain out, the heater should be blown out with low pressure compressed air to remove as much water as possible from water heater modules. Bursts of air work better than continuous flow.
Remember, these suggestions are only made to help minimize the potential for freeze damage and are not to be construed as the guaranteed method for dealing with freeze possibilities.
What to Watch Out For When Reading Other Reviews
While doing research for this article, we came across many crappy products that had bad reviews for numerous reasons, or cases where seller claims were invalid. Some things to watch out for include:
- Devices claiming to be tankless but actually use mini tanks (mini tanks will be a separate article).
- Seller claiming the product could be used for a shower, bath tub, pool, sauna, but didn’t have enough water flow or enough temperature rise to handle more than .5 GPM for a sink.
- Product could only be used in the far south of the USA because it could not provide enough temperature rise.
- Product never worked, or only worked for 20 minutes, or actually melted.
Compare The 9 Best 120-110 Volt Tankless Water Heater Choices
The table below shows the main technical specifications for the 9 tankless water heaters discussed in this review:
|Model||Voltage||Power||Amps||Wire Size||Min GPM||Max GPM||Temp rise at 0.5 GPM|
|iHeat HS-4||110 V||3.2 Kw||29 A||10 AWG||0.25 GPM||2 GPM||41 °F|
|Stiebel Eltron DHC 3-1||120 V||3.0 Kw||25 A||10 AWG||0.32 GPM||1.14 GPM||41 °F|
|Stiebel Eltron Mini 3-1||110 V||3.0 Kw||25 A||10 AWG||0.4 GPM||41 °F|
|Rheem RTEX-04||120 V||3.5 Kw||29 A||10 AWG||0.3 GPM||1.5 GPM||48 °F|
|Bosch Tronic 3000C US3||120 V||3.4 Kw||27 A||10 AWG||0.35 GPM||1 GPM||41 °F|
|Chronomite SR-30L||120 V||3.5 Kw||30 A||10 AWG||0.35 GPM||1 GPM||49 °F|
|Ecosmart POU 3.5||120 V||3.5 Kw||29 A||10 AWG||0.3 GPM||1 GPM||47 °F|
|Eemax EEM12004||120 V||4 Kw||29 A||0.35 GPM||2 GPM||48 °F|
|AHSH 2500||110 V||3.3 Kw||30 A||10 AWG||0.48 GPM||1.25 GPM||47 °F|
Our 9 Best 120-110 Volt Tankless Water Heaters
#1. Drakken iHeat Hotspot HS-4 Electric Tankless Water Heater – 110 Volt
The HS-4 point of use electric tankless water heater by iHeat comes in a stainless steel enclosure.
The temperature can be safely and easily controlled by making use of Drakken’s water proof interactive touch pad. This allows users to select any temperatures between 80°F and 140°F.
The Department of Energy recommends that water heaters should be set at 120°F.
The power drawn for the heater is calculated by using real time data based on behavioral use. This data is then applied to the unit’s closed loop modulation system. This water heater also features activation at a mere 0.25 GPM flow.
- Compact size saves valuable space and makes it suitable to be installed in closets or under counters.
- Suitable for use in sterile applications, including hospitals, commercial kitchens, schools and clinics.
- Water heating costs can be reduced by up to 60%.
- Suitable for use with a kitchen sink, or in warm climate zones, with a very low flow shower.
- (Underwriters Laboratory) UL Listed
Notes: This product has a number of features that are not available on other products including:
- Adjustable thermostat.
- Closed loop modulation.
#2. Stiebel Eltron DHC 3-1 Single Sink Point-of-Use Tankless Electric Water Heater 120V
The Stiebel Eltron DHC 3-1 is suitable for delivering hot or warm water to a single point, e.g. a utility sink or a hand wash basin.
Many years of reliable service is made possible by the all copper, rugged design.
The reliability and simplicity of these tankless water heaters make them ideal for use in various residential applications such as:
- Utility, kitchen and bathroom sinks
- RVs and Boats
- Laundry Areas
They are also ideal for use in kitchenettes and restrooms in several industrial, commercial, or office settings, including:
- Gas Stations
- Office Buildings
- Motels and Hotels
- Commercial Condominiums
- Manufacturing Facilities
DHC-E Provides Electronic Accuracy
DHC-E delivers hot water to a single or multiple sinks, or in specific conditions, to low-flow showerheads.
Simply Set a Dial To The Desired Temperature
The dial on the front cover can be used to set the temperature to between 86 and 140 °F (30 and 60 °C), and can be changed at any time. Even if the water flow varies, advanced microprocessor technology will ensure that the temperature of the water remains at the set point.
Constant Temperature Output
DHC-E water heaters use Stiebel Eltron’s Electronic Temperature Control. This compensates for incoming water temperature variations and flow rate fluctuations to ensure that a constant output water temperature is maintained. The smart microprocessor technology saves power by continually monitoring information from two temperature sensors and the flow sensor. This data is then used to micro-adjust the heating elements.
- Heats water instantly.
- Use up to 50% less power vs tank type units.
- Safety high limit switch prevents dry firing, protecting the heater against burn-out.
- Quiet operation via hydraulic control, eliminating clicking noise when turning off and on.
- Decreased installation costs compared to storage type heaters.
#3. Stiebel Eltron Mini 3-1 Mini Single Handwashing Sink Tankless Electric Water Heater
This model is this is a downgraded version from the Stiebel Eltron DHC 3-1 described above and is physically smaller.
- Saves energy.
- Space saving compact design.
- Sleek design and can be mounted in plain sight.
- Provides unlimited hot water.
- 3 years warranty on parts and 7 years on leakage.
- Proven reliability.
- Manufactured in the USA.
- Safety high-limit with manual reset included.
- Three year limited warranty – product must be installed by licensed personnel.
- The model Mini 3-1 is supplied with a 0.5 GPM pressure compensating flow reducer / aerator. Installation of the aerator is required by the manufacturer.
#4. Rheem RTEX-04 3.5kW Electric Instantaneous Water Heater – 120V
This instantaneous water heater by Rheem provides continuous hot water on demand.
These units can either be used as single point-or-use, or for multiple applications simultaneously.
This model of tankless water heater is more efficient than standard tank-based hot water heaters, and boasts an energy efficiency of 99.8%.
- Easy replacement facilitated by threaded heating elements.
- Maximum flow rate of 1.5 GPM (Gallons per Minute).
- Stylish and compact.
- Output temperature between 80°F and 140°F.
- Continuous and consistent hot water on demand.
- Simple installation.
- Highly durable with robust copper immersion heating elements with brass tops.
- Adjust temperature with external controls in increments of 1°F.
- Digital temperature display.
- Water Quality Association tested and certified as per NSF/ANSI 372 for lead free compliance.
- 1-year parts limited and 5-Year heating chamber warranty.
- All circuit protection (breakers) and wiring (wire gauge) used for installation must comply with the Canadian Electrical Code (CEC), or the U.S. National Electrical Code (NEC). Failure to do so may result in personal injury and/or property damage, and void the warranty. Insurance companies do not cover damages unless installed by a licensed professional.
- It is recommended that the unit be installed in an upright position with the outlet and inlet water connections at the bottom of the unit to facilitate ease of installation and servicing.
#5. Bosch Tronic 3000C US3 Pro Point-of-Use Electric Tankless Water Heater – 3.4Kw 120volt
The Bosch Tronic 3000C 7736500685 is a tankless water heater designed to heat water for any point of use application.
With its ability to instantly heat water and no bulky tanks to worry about, this water heater provides constant and infinite hot water to your home all within a small cabinet size.
Thus, making the Bosch 3000C 7736500685 an ideal candidate in almost any sink application.
- 0.7 maximum gallons per minute, 3.4kW electrical tankless water heater
- 98% heat transfer efficiency
- Designed for heating water at point-of-use applications, on demand and with no interruptions
- Supports up to a 45°F water temperature rise
- Simplistic installation design
- Compact and light weight, a true space-saving solution
- Do not install the heater in a location where it may be subject to freezing.
- Do not install a check valve or any other types of back flow preventer within six feet of the cold water inlet.
- If the unit is to supply a sink, you can fit it either above or below the sink.
- The heater must only be wall mounted and positioned with the water connections located either at bottom or the right side of the unit.
#6. Chronomite SR-30L/120 HTR SR Series Instant-Flow Low Flow Tankless Water Heater
The patented Chronomite microprocessor technology enables controlled or pre-set output temperatures to be delivered accurately within two seconds rather than the six seconds required by other tankless water heaters.
These water heaters are installed at point of use and will only operate when hot water is required. This dramatically reduces inefficient use of electricity and hot water delivery times.
- Flow rate: 0.5 GPM.
- Rear electric knock-out.
- Designed for horizontal under-sink installation, unlike others that require vertical installation.
- Two chrome compression fittings included.
- 3/8” water outlet and inlet connections.
- To reach 105 degrees (hot water) at .5GPM the incoming water temperature must be at least 56 degrees.
- A water restricting governor needs to be installed on the sink to limit the flow.
- The temperature can’t be adjusted, but is factory preset at 110 °F
#7. Ecosmart POU 3.5 Point of Use Electric Tankless Water Heater
The Ecosmart POU 3.5 has been designed for single applications with a maximum flow rate of 0.5 GPM.
It is installed under the sink and includes a 0.5 GPM sink aerator.
The flow controlled heater enables the temperature to be adjusted based on the flowrate.
This Ecosmart electric tankless model should only be used to run one sink at a time. It is also only suitable for areas where the inlet water temperature is 57°F or higher. The ECO POU 3.5 can heat inlet water at 57°F to 105°F at a flowrate of 0.5 gallons per minute.
Under the sink installation is possible due to the unit’s compact size. The water heater is ideal for: strip malls, wet bars, boats, doctor’s office, bathroom sinks and recreational vehicles (RVs). This water heater will provide an endless supply of hot water provided it is sized properly.
Before purchasing and installing consumers should verify that this model is sized correctly for the required demand and electrical requirements. The Ecosmart POU 3.5 should only be installed using #10 AWG wire with a 30 amp single pole breaker. 1/2″ NPT plumbing connections should also be used.
- This product should only be used with a single sink and is not suitable for use with multiple fixtures or a shower.
- Compact size.
- Endless, consistent hot water on-demand.
- Maximum flow rate: 0.5 GPM (gallons per minute).
- 0.5 GPM sink aerator included.
- Stainless steel and copper components allow for durability, efficiency and easy replacement.
- Digital output temperature display.
- Only for use in the Southern USA.
- This unit is not modulated, and the output temperature cannot be selected
- This product is ETL Listed to UL 499 & CSA.
#8. Eemax EEM12004 4kW Electric Tankless Point of Use Water Heater, Blue
Eemax electric tankless water heaters provide endless hot water where you need it and when you need it.
This product can be used for any of your residential or commercial water heating needs.
The EEM12004 is most often used for single lavatory sink applications. The unit operates from 120 volts, and delivers 4 Kw of power.
It has been designed to operate in warmer climates and is suitable for point of use applications with a flowrate of 0. 5 GPM (gallons per minute.
- Provides consistent, instant, and endless hot water.
- Tank less water heaters provide a continuous supply of hot water and only heats the water you need, when you need it.
- Advanced, self-modulating technology enables the unit to adjust how much energy is needed based on how much hot water is required.
- Compact size saves valuable storage space.
- Verify that this unit is sized correctly for the required hot water needs before purchase and installation.
- Utility, bar and kitchen sinks.
- Hand set shower (0.7 to 2.0 GPM)
- Hand basins (0.35 to 2.0 GPM)
- Manufacturing facilities
- Modular tenant spaces and buildings
- Dual hand basins (DL option)
- Mobile Home approved
- Endless hot water due to storage capacity not required.
- Heater activated by flow switch on demand, eliminating standby heat losses.
- High temperature limit switch with automatic reset.
- Easy installation.
- Wall mounted.
- Temperature & Pressure (T&P) relief valve not required depending on local codes.
- Patented, unique flow path ensures extended element life and optimum heat transfer.
- Ni Chrome element.
- Proper temperature increase via optional flow restricting aerator (for EX-DL models). Standard with SP models.
- Flexible installation due to compact size.
- One year parts warranty, five years limited warranty on leaks.
- Suitable for ADA compliant facilities
Not suitable for use in application with an inlet temperature of less than 57 °F.
#9. Drakken iHeat Tankless Electric Shower Head With Heater AHSH 2500
This 110 volt electric shower head with heater needs to be screwed onto the shower outlet.
The temperature is controlled via two buttons that are labeled low and high.
- Stainless Steel Finish
- Includes 1 Shower Head and 1 Heater
- Maximum Temperature 116.6 Fahrenheit
- Minimum Temperature 75.2 Fahrenheit
- Adjustable thermostat Included
- Suitable for Indoor and Outdoor Use
- Weather Resistant
- Mobile Home Approved
- Cord length: 36 inches
- Water connection: 0.5 inches
- Designed with a completely waterproof enclosure and has the ability to be used in the shower, outdoors, and even on your hunting or camping trips.
- Can be used inside a recreational vehicle (RV), assuming you have adequate power available.
Conclusions: 120-110 Volt Tankless Water Heater Reviews
Generally speaking, if you have 110 volt electrical service in your house, then use a 110 volt tankless water heater. However, if you have 120 volt service, then a 110 volt tankless water heater isn’t your best bet.
That’s because you are asking the device to “work” harder than it was designed for. The result? It might not last as long as it could have.
None of these 120-110 volt tankless water heater choices are going to perform like their 240 volt “big brothers” that can provide hot water to multiple sinks and showers.
However, the tankless heaters in this article are the best choices available for most people in the U.S. for low flow hot water needs.