15 Best Whole House Tankless Water Heaters Today

In Brief: Best Whole House Tankless Water Heater

  1. EcoSmart ECO 27 
  2. Stiebel Eltron Tempra Plus 
  3. Stiebel Eltron Tempra Plus 20 Plus 
  4. Stiebel Eltron 24 Plus Tempra
  5. Eccotemp FVI12-LP
  6. Bosch Electric Tankless Water Heater
  7. Rinnai RL94EP 
  8. Takagi T-H3-DV-N 
  9. Rheem 240V Heating Chamber RTEX-13
  10. Rinnai RUC98iN Ultra Series 
  11. Atmor AT-910-24TP 
  12. Takagi T-K4-IN-NG
  13. iHeat Tankless S-14 
  14. Eemax EEM24018 
  15. Marey ECO150 
How We Decided

39 products considered. 1100+ reviews analyzed, 43 research hours spent, 25+ info. sources referred

More about our Methodology

Hot water is an essential requirement in most households. And having a big house shouldn’t mean that one has to buy several water heaters and install them at every water outlet to ensure hot water supply for their needs.

This is where whole house tankless water heaters come into the picture.

Not only is installing multiple tankless water heaters around the house inefficient, but it is also cost-intensive and would unnecessarily duplicate the efforts in maintenance and upkeep.

A whole-house tankless water heater can be installed at a single location anywhere in the house and be connected to multiple points of application.

The capacity of a whole house tankless water heater is sufficient to simultaneously fulfill hot water needs by opening many faucets at the same time.

It removes the need for one to purchase many heaters and reduces the costs in the process.

Comparison Table: Top Whole House Tankless Water Heaters

Check out the key parameters of top tankless water heaters compared – 

ProductFlow Rate (GPM)Weight (lbs)Energy EfficiencyPrice

EcoSmart ECO 27

EcoSmart ECO 27 Electric Tankless Water Heater, 27 KW at 240 Volts, 112.5 Amps with Patented Self Modulating Technology

3 16.8 50% Check Price

Stiebel Eltron Tempra Plus 29 kW

Stiebel Eltron Tankless Water Heater – Tempra 29 Plus – Electric, On Demand Hot Water, Eco, White

4.5 13 80% Check Price

Stiebel Eltron Tempra Plus 20 Plus

Stiebel Eltron 224198 240V, 1 Phase, 50/60 Hz, 20 kW Tempra 20 Plus Whole House Tankless Electric Water Heater, Advanced Flow Control

4.5 16.1 80% Check Price

Stiebel Eltron 24 Plus Tempra

Stiebel Eltron Tankless Water Heater – Tempra 24 Plus – Electric, On Demand Hot Water, Eco, White

2.6-5 24 99% Check Price

Eccotemp FVI12-LP

Eccotemp FVI12-LP Liquid Propane Gas Tankless Water Heaters, White

3.6 33 Check Price

Bosch Electric Tankless Water Heater

Bosch Electric Tankless Water Heater - Eliminate Time for Hot Water - Easy Installation

3.5 19.5 97% Check Price

Rinnai RL94EP

Rinnai RL Series HE+ Tankless Hot Water Heater: Outdoor Installation

9.4 44.3 Check Price

Takagi T-H3-DV-N

Takagi T-H3-DV-N Condensing High Efficiency Natural Gas Indoor Tankless Water Heater, 10-Gallon Per Minute

10 59 Check Price

Rheem 240V Heating Chamber RTEX-13

Rheem 240V Heating Chamber RTEX-13 Residential Tankless Water Heater

1.5 8.5 99.80% Check Price

Rinnai RUC98iN Ultra Series

Rinnai RUC98iN Ultra Series Indoor Natural Gas Tankless Water Heater, Twin Pipe

9.8 82 92% Check Price

Atmor AT-910-24TP ThermoPro

Atmor AT-910-24TP ThermoPro 24 kW/240V 4.6 GPM Digital Tankless Electric Water Heater, Grey

4.6 17 Check Price

Takagi T-K4-IN-NG

Takagi T-K4-IN-NG Indoor Tankless Water Heater, Natural Gas

8 43 82% Check Price

iHeat Tankless S-14

iHeat Tankless S-14 240V 59A 14KW Stainless Steel Enclosure 7.2' by 11' by 3' 1/2'CPT 36' AWG#6 Electric Water Heater, 7.5 lb

3 8 60% Check Price

Eemax EEM24018

Eemax EEM24018 Electric Tankless Water Heater, Blue

3.5 14.5 Check Price

Marey ECO150

Marey ECO150 220V/240V-14.6kW Tankless Water Heater with Smart Technology, Small, White

2.5 10.1 Check Price

Table of Contents

The article finally reviews the top fifteen best products in the whole house tankless water heater category.

An amalgamation of all this information will be quite essential as a quick start guide for any person looking to purchase a whole house tankless water heater.

Reviews of the Whole House Tankless Water Heater

1.best overall rating

EcoSmart ECO 27 Electric Tankless Water Heater

EcoSmart ECO 27 Electric Tankless Water Heater, 27 KW at 240 Volts, 112.5 Amps with Patented Self Modulating Technology

Ecosmart as the name suggests, is focused entirely on creating green and sustainable products.

Their line of tankless water heaters is the only business they are invested in and all their products have a patented self-modulating technology which is used for saving energy by cutting down the electricity consumption by almost 50%.

The company is based out of the United States and apart from water heaters, they also manufacture related heating equipment like pool heaters, shower heaters etc.

All of their products are available in commercial and residential variants.

This tankless water heater by EcoSmart has an activation flow rate as low as 0.3 GPM. The design of this unit is sleek and compact allowing it to be fitted into the tiniest of spaces easily.

The components of the heater are made of stainless steel and copper which ensures efficiency and durability. The design also allows for easy replacement and repairs.

The tankless model also boasts of cost savings of a whopping 50% for heating water. EcoSmart offers a limited lifetime warranty for this model.

This water heater weighs 16.8 lbs and the dimensions of the same are 17H x 17W x 3.625D inches.

Check out how to install an EcoSmart water heater here :

 

Some of the key USPs of this whole house electric tankless water heater is listed below :

  • Patented self-modulating technology
  • Increased temperature control with increments as small as 1 °F
  • Space consumption reduced by 12 cubic feet due to compact design
  • Durable design of components made of copper and stainless steel
  • Output water temperature ranging from 80 °F – 140 °F
  • Can handle water flows up to 6 GPM
PROS:
  • Capable of heating water as low as 37 °F at 3 GPM
  • Customers happy with the product performance
  • Rated high on energy efficiency
  • Great features on the temperature control
  • Easy on the budget
CONS:
  • Most customers were unhappy with the warranty terms

Check Reviews & Price on Amazon

2.best overall rating

Stiebel Eltron Tempra Plus 29 kW, Tankless Electric Water Heater

Stiebel Eltron Tankless Water Heater – Tempra 29 Plus – Electric, On Demand Hot Water, Eco, White

Stiebel Eltron was established way back in May 1924. It is a German based manufacturer of many products in the heating space and is currently headquartered at Holzminden, Germany.

Their product line includes a wide range of heating solutions like water boilers, heat pumps, hand dryers, electrical heaters, taps etc.

This Stiebel Eltron product is a part of the Tempra Plus series. The ‘29’ in the name of the product is indicative of its power rating which stands at around 29 kW.

The name of this company is synonymous with reliability and good performance. The model is designed to be extremely sleek so as to increase the ease of installation for the customer even in the smallest spaces inside their homes.

Some of the special features of this tankless water heater are inbuilt sensors that detect as soon as a trickle of water flows when a faucet is turned on.

This then allows the unit to be triggered on and to utilize the exact amount of energy needed to heat that water at the temperature set by the user and according to the pressure of the flow.

The unit does not require any special venting.

The output temperature of this unit varies anywhere from 86 °F and 125 °F and the user can set it to any temperature in this range using the digital display at the front of the heating unit.

The product weighs 10.39 lbs and the dimensions of the same are 16.5 x 4.6 x 14.5 inches.

Some of the key USPs of this whole house electric tankless water heater is listed below :

  • Offers separate warranty terms for commercial and residential usage
  • Increased accuracy in temperature control
  • Easy access to components due to a hinged cover design
  • Features upgraded heavy-duty electronics
  • A simple single flow sensor design
  • Advanced flow control
PROS:
  • Budget friendly
  • Able to support multiple water outlets at the same time
  • Good energy efficiency
  • Technical support service is good
  • Good temperature control functionality
CONS:
  • Professional installation which is required is cost intensive
  • Customers expect a better product life

Check Reviews & Price on Amazon

3.best overall rating

Stiebel Eltron Tempra Plus 20 Plus Whole House Tankless Water Heater

Stiebel Eltron 224198 240V, 1 Phase, 50/60 Hz, 20 kW Tempra 20 Plus Whole House Tankless Electric Water Heater, Advanced Flow Control

This tankless electric water heater by Stiebel Eltron is a part of the distinguished Tempra Plus series. The ‘20′ in the name signifies the 20 kW power rating that the unit has been stamped with.

The unit is equipped with electronic control to provide consistent hot water temperatures even if the flow varies.

It also boasts of an intelligent self-modulating technology that continually saves energy by ensuring the least amount of electricity is used to heat the water.

The Tempra Plus models also offer the additional comfort of Advanced Flow Control that provides the desired hot water temperature even when demand exceeds the capacity.

This tankless water heater weighs 16.1 lbs and the dimensions of the same are 16.5 x 4.6 x 14.5 inches.

Some of the key USPs of this whole house tankless water heater is listed below :

  • Sleek design that fits anywhere
  • No venting required
  • Saves 15% to 20% on the electric bill
  • Multiple heating elements activated according to demand
  • Output water temperature range of 86 °F – 140 °F
  • A minimum flow rate of 0.50 GPM for activation of the unit
  • Equipped with preset temperature memory buttons
  • Copper sheathed heating element housed in a copper cylinder
  • 7-year leakage and 3-year parts warranty
PROS:
  • Temperature control feature is good
  • Technical support is rated well
  • Noiseless operations due to electronic switch activation
  • High energy efficiency
CONS:
  • Product life could be longer
  • Installation costs are too high

Check Reviews & Price on Amazon

4.best overall rating

Stiebel Eltron 24 Plus Tempra, Tankless Water Heater

Stiebel Eltron Tankless Water Heater – Tempra 24 Plus – Electric, On Demand Hot Water, Eco, White

This Stiebel Eltron product is another offering from their Tempra Plus series that has an electrical rating of around 24 kW.

The heating components are entirely made of a copper sheathing and are also housed inside a copper body known for its good conducting properties.

The heater does not require any venting which is a very big plus when it comes to installation needs.

This unit is equipped with a smart technology that allows it to regulate the energy according to the water pressure and the required temperature.

The water heater comes with a seven-year leakage and three-year complete parts warranty. It weighs a meager 1 lb and the dimensions are 4.6 x 16.6 x 14.5 inches.

Some of the key USPs of this whole house electric tankless water heater is listed below :

  • Virtually noiseless operations owing to electronic switch activation
  • Can support multiple water pressures and temperature rations according to requirement
  • Tested and certified by WQA against NSF/ANSI 372 for lead-free compliance
PROS:
  • Unit is an easy install
  • Customers are happy with the component quality
  • Unit works very silently
  • Reliable and good performance
  • A great temperature control feature
  • Positive impact on the electricity bill
CONS:
  • Can cause the circuit breaker to trip at times while usage
  • Copper components prone to corrosion and clogging faucets with debris

Check Reviews & Price on Amazon

5.best overall rating

Eccotemp FVI12-LP Liquid Propane Gas Tankless Water Heaters

Eccotemp FVI12-LP Liquid Propane Gas Tankless Water Heaters, White

Started in 2004 as a small family owned business, Eccotemp is now a big name in the market of energy-efficient water heaters. It is a company based out of Charleston, Summerville, South Carolina.

The different kinds of tankless water heaters that they manufacture and sell fall into the portable, whole house and electric categories.

They also sell parts and equipments for all their products which is useful for repairs or replacements.

This Eccotemp water heater operates at minimal noise levels. It is a product developed for serving the hot water needs for an entire household. The water flow output for this unit is pegged at 3.6 GPM.

There is a mechanism for energy conservation which activated the unit only when a certain minimum water pressure is detected.

Since it is a gas based model, sufficient space is needed for installation of the ventilation pipes. However, the company made the design of the heater extremely space efficient and compact.

The system is equipped with a safe electronic ignition system. There is a digital display that allows setting and modifying the temperature in increments as low as a degree.

The heater kit includes equipment like a horizontal venting, a 2 1/2″ 90-degree Elbow with Backflow Preventer, termination pipe and other installation hardware along with the water heater.

The unit weighs 33 lbs and the dimensions of the same are 29 x 17 x 11 inches.

Some of the key USPs of this whole house tankless gas water heater is listed below :

  • Can be used with a 20 to 100-pound (lb.) propane tank
  • 2 year limited warranty
  • Temperature range of 80 °F – 140 °F
  • Manual temperature controls
PROS:
  • Rated high on energy savings
  • Installation process is easy
  • Pocket friendly purchase
  • Customers were happy with the customer service
CONS:
  • May not perform suitably in extreme climatic conditions

Check Reviews & Price on Amazon

6.best overall rating

Bosch Electric Tankless Water Heater

Bosch Electric Tankless Water Heater - Eliminate Time for Hot Water - Easy Installation

Bosch is a company that needs no introduction when it comes to a wide range of products. The company has been in business for almost 280 years and there is no other organization that comes close to that experience in technology.

Bosch Thermotechnology is the specially developed division of the company that deals with all products involving heating technology and hot water solutions.

Their focus is on developing environmentally viable green solutions and reducing the carbon footprint of many devices used in our day to day lives.

This tankless water heater by Bosch is rated at 26.9 kW and is a whole house water heater.

This WH 27 heater is a part of the Bosch Tronic 6000 C series and it can easily supplement the hot water needs of an entire household. The polymer encased elements and built-in flow sensor ensures constant output temperature.

The external temperature control knob gives superior temperature stability and control.

The unit boasts of 97% thermal efficiency with minimal stand-by loss. The heater can deliver hot water to a maximum of three outlets at a time. It weighs 19.5 lbs and the dimensions of the same are 15.5 x 4.5 x 12.5 inches.

Some of the key USPs of this whole house tankless water heater is listed below :

  • 97% thermal efficiency
  • A 3.5 GPM output at a 45-degree temperature rise
  • 10 year and a 3-year warranty on the heating module and parts respectively
PROS:
  • Inexpensive, budget-friendly purchase
  • Easy to install
  • Works as advertised
  • Good technical support
  • Great brand reputation
CONS:
  • Product life is short

Check Reviews & Price on Amazon

7.best overall rating

Rinnai RL94EP Tankless Water Heater, Large, RL94eP-Propane/9.4 GPM

Rinnai RL Series HE+ Tankless Hot Water Heater: Outdoor Installation

Rinnai Corporation was founded by Kanekichi Hayashi and Hidejiro Naito in Japan way back on 1st September 1920.

It is primarily a home appliance company and a leading player in the residential and commercial markets for gas based tankless water heaters.

They also offer a few other products and these are all in the gas based home heating space.

This propane-based tankless water heater is made for outside installation only. It has a very impressive output water flow rate of 9.4 GPM. This rate may vary according to the groundwater temperature.

It can comfortably support up to six fixtures which is more than the industry average. This tankless gas water heater is also approved by the South Coast Air Quality Management District for residential usage.

The unit weighs 44.3 lbs and the dimensions of the same are 14 x 10 x 23 inches.

Some of the key USPs of this whole house tankless water heater is listed below :

  • WiFi-enabled tankless water heater
  • Comes with a residential warranty (180, 12 and 60 months on heat exchanger, labor and parts respectively)
  • CIRC-LOGIC Recirculation Technology capable unit
  • Uniform Energy Factor Rating of 0.81
PROS:
  • Reputed brand
  • The good quality construction of the water heater
  • Kit includes isolation and pressure valves
  • Easy to repair
  • Good capacity of the water heater is a plus
  • Has the option of connecting to battery backup
  • Great for home brewing
CONS:

Check Reviews & Price on Amazon

8.best overall rating

Takagi T-H3-DV-N Condensing High-Efficiency Natural Gas Indoor Tankless Water Heater

Takagi T-H3-DV-N Condensing High Efficiency Natural Gas Indoor Tankless Water Heater, 10-Gallon Per Minute

Takagi is a 60 year old company established way back in 1952 and has since been developing environment friendly water heaters.

Their product line is centered around water heaters and they manufacture and sell high quality tankless water heaters for residential and commercial applications.

With one of the highest flow rates in the residential tankless water heater industry (10 GPM), this model is more than adequate for meeting the hot water requirements of an entire household easily.

Not only does it serve houses well, due to its high capacity it is also often employed by small business like a restaurant or a salon. It can also be used for other purposes like space heating and in recirculation systems.

Copper, which is almost 25 times better than steel at exchanging heat, is the primary component of the commercial grade heat exchanger tubing.

The unit has minimal NOz emissions that are well within the limits set by the state of California. The unit can handle up to 4 showers simultaneously in warmer climates and three in cold ones.

It is designed to be space-saving and energy-efficient. The water heater weighs 59 lbs and the dimensions of the same are 11.2 x 17.8 x 24.9 inches.

Check out the installation of this water heater at :

 

Some of the key USPs of this whole house tankless gas water heater is listed below :

  • Satisfies the 2012 SCAQMD Rule 1146.2
  • Energy-star certified
  • 15 years and 5 years limited warranty on the heat exchanger and parts respectively, for residential use
  • Output water temperature range of 100 ºF – 185 ºF.
PROS:
  • Great energy efficiency
  • Performs well under challenging conditions
  • The output flow rate of hot water is good
  • Instantly supplies hot water
CONS:
  • Weighs a little higher than average

Check Reviews & Price on Amazon

9.best overall rating

Rheem 240V Heating Chamber RTEX-13 Residential Tankless Water Heater

Rheem 240V Heating Chamber RTEX-13 Residential Tankless Water Heater

Rheem Manufacturing Company is headquartered at Atlanta, Georgia, United States, however its roots were established in Emeryville, California by brothers Donald and Richard Rheem.

The company will soon become a century old in the business of producing a wide range of products for commercial and residential usage. These products are pool heaters, air conditioners, HVAC systems and furnaces.

Apart from these, they have gained wide popularity of their water heaters.

The unit is highly energy efficient boasting a whopping 99.8% in terms of energy conservation. This is possible owing to their patented self-modulating power control.

This system allows for the energy consumption to be regulated according to the water flow and usage. The unit is rated at 13 kW and 240 V. This water heater also enjoys immense popularity for its consistent hot water supply.

This is possible owing to the two durable copper immersion heating elements.

The model design is simple and user friendly allowing for aid in easy repairs and replacement. The heater kit includes a 3-foot electrical cable and ½ inch NPT adapters.

The external adjustable digital thermostatic control with the LED display allows for a great level of accuracy while setting the temperature.

It can easily serve a water saver shower head at 1.5 GPM. The water heater weighs 8.5 lbs and the dimensions of the same are 4 x 9 x 13 inches.

Some of the key USPs of this whole house electric tankless water heater is listed below :

  • Advanced temperature control
  • Patented self modulating temperature technology
  • Comes with a limited 5 years no-leak warranty and 1-year parts warranty
  • One of the best units for residential use
PROS:
  • Allows good precision in setting unit temperature
  • Highly energy efficient (one of the best ratings in industry)
  • Quick to supply hot water
  • Money saver design
  • Works effectively in serving multiple outlets
CONS:
  • Customers unhappy with product life

Check Reviews & Price on Amazon

10.best overall rating

Rinnai RUC98iN Ultra Series Natural Gas Tankless Water Heater

Rinnai RUC98iN Ultra Series Indoor Natural Gas Tankless Water Heater, Twin Pipe

This tankless water heater is a part of the Sensei series which is known to be a condensing type heater series. This eliminates the need for extensive venting that is needed in the non-condensing type models.

Due to this feature, the heater is also very suitable for an indoor installation. The energy efficiency rating for this heater ranges between 0.92 and 0.96.

The output water temperature range for commercial tankless water heaters is 98° F to 185 ° F and for residential tankless water heaters is 98° F to 140° F. The unit has an impressive power output at 199,000 BTU per hour.

This high number signifies that the unit can support a minimum and maximum number of three to six outlets respectively.

This number can vary according to the weather conditions but is still fairly good compared to other models in the industry of comparable capacity.

Fast hot water delivery is supported by recirculation technology. The unit has ultra-low NOx emissions. It weighs 82 lbs and the dimensions of the same are 10 x 18.5 x 26 inches.

Check out the details of this product at https://www.youtube.com/watch?v=tjzYsshqKMo.

Some of the key USPs of this whole house tankless gas water heater is listed below :

  • Recirculation technology is supported
  • 12-year warranty on the heat exchanger and 5-year warranty on parts
  • A good flow rate of 9.8 GPM (one of the highest in industry)
PROS:
  • Rated high on the ease of installation
  • Long lasting product
  • Customers happy with the performance of the unit
CONS:
  • Unit is slightly heavy
  • Users expected a better output water temperature range

Check Reviews & Price on Amazon

11.best overall rating

Atmor AT-910-24TP ThermoPro 24 kW/240V 4.6 GPM Digital Tankless Electric Water Heater

Atmor AT-910-24TP ThermoPro 24 kW/240V 4.6 GPM Digital Tankless Electric Water Heater, Grey

Atmor Industries Ltd has been in the business of manufacturing electric tankless water heaters for over 30 years now. They have sold over 2 million units worldwide.

They are exclusively focused on the development of efficient electric water heaters.

This digital tankless water heater by Atmor can comfortably support residential usage and provide hot water in as quickly as 15 seconds after the faucet is turned on.

The unit is focused on energy conservation and uses electricity only when the water flows through it.

The adjustable temperature of the unit is possible with the digital temperature control unit housed on the unit’s front which allows adjustment in increments or decrements of one degree.

The unit comes installed with a thermal switch as a part of a safety mechanism that prevents the unit or the water from getting too hot.

When it reaches a certain peak temperature, the switch causes the unit to trip and cool down before turning back on again.

The flow sensors prevent the unit from turning on until a minimum flow level is reached. The unit weighs 17 lbs and the dimensions of the same are 17.4 x 5.2 x 13.4 inches.

Some of the key USPs of this whole house tankless water heater is listed below :

  • Interior components made of high-quality stainless steel
  • 7 years leakage and 2 years parts warranty
  • Can heat incoming water temperature as low as 37 °F at 2.45 GPM
  • Ideal for supporting up to 4 operations simultaneously
PROS:
  • Well made unit
  • Great aesthetic appeal
  • The digital display is good
  • Great savings on the electricity bill
  • Decent price point
  • Recommended by users
CONS:
  • Pressure relief valve not included in the kit

Check Reviews & Price on Amazon

12.best overall rating

Takagi T-K4-IN-NG Indoor Tankless Water Heater, Natural Gas

Takagi T-K4-IN-NG Indoor Tankless Water Heater, Natural Gas

This tankless water heater by Takagi is for indoor installation only and works on natural gas. There is an option for a direct vent conversion. The heat range of this device varies from 11,000 to 190,000 BTUs per hour.

It has an energy factor of 0.82.

The maximum flow rate of this tankless water heater is 8.0 GPM. The unit weighs 38 lbs and the dimensions of the same are 8.5 x 13.8 x 20.5 inches.

This ultra-compact design allows for it to be mounted anywhere on the wall strategically so it doesn’t take up too much space. It is a very efficient and environmentally friendly unit.

The unit is capable of saving up to 45% on the monthly gas bills.

Some of the key USPs of this whole house tankless water heater is listed below :

  • Perfect for domestic applications as well as hydronic or radiant heating applications
  • Supports water pressure range of 15 PSI to 150 PSI
  • The temperature range of the output water is 99 °F to 167 °F
PROS:
  • Instant hot water on demand
  • Good value for money
  • Semi-reasonable installation procedure
  • Good performance of the unit
  • Lightweight
  • Efficient and great water output
  • Smaller carbon footprint
  • Great space saver design
CONS:
  • Takes time for hot water to reach the faucet

Check Reviews & Price on Amazon

13.best overall rating

iHeat Tankless S-14 240V 59A 14KW Electric Water Heater

iHeat Tankless S-14 240V 59A 14KW Stainless Steel Enclosure 7.2' by 11' by 3' 1/2'CPT 36' AWG#6 Electric Water Heater, 7.5 lb

This tankless water heater by iHeat is a part of the S series that is manufactured in complete stainless steel and boasts an ixp-4 waterproof construction. This particular model of water heater is rated at 14 kW.

The compact size of this heater saves valuable space with its compact size and can be fitted into closets as well.

It can save up to 60% on water heating costs. The waterproof construction allows one to easily and safely control the temperature by using the interactive waterproof touchpad.

The unit weighs a meager 8 lbs and the dimensions of the same are 3.5 x 7.7 x 11.5 inches. The hot water output of this unit stands at 3 GPM which can comfortably support 2 showerheads at the same time.

Some of the key USPs of this whole house tankless water heater is listed below :

  • Stainless steel components
  • A maximum output flow rate of 3 GPM
  • Saves up to 60% on heating costs
PROS:
  • Works as advertised
  • Installation was easy
  • Good value for money
  • Compact size
  • Great safety feature for keeping the temperature in check
CONS:
  • Best suited only for warm weather states
  • Slight delay in getting hot water

Check Reviews & Price on Amazon

14.best overall rating

Eemax EEM24018 Electric Tankless Water Heater

Eemax EEM24018 Electric Tankless Water Heater, Blue

Eemax Inc. is a subsidiary of the well-known water heater brand Rheem and was founded in 1988. The company was originally established as a manufacturer of commercial tankless water heaters.

In 2000, the company first introduced a line of residential products. In 2013, Eemax acquired the well-known company of water heaters EcoSmart.

Their entire range of products includes several customized lines of water heaters for commercial and residential application.

This electric tankless water heater by Eemax supplies an instant, consistent and continuous supply of hot water.

The unit is equipped with a self-modulating technology which means that it will adjust energy input based on how much hot water is needed. The heater has a compact design that saves on the valuable space.

The exteriors are stylish and weather resistant. There is a digital temperature control featured on the front that allows increments as small as one degree for a temperature range of 80 °F to 140 °F.

The unit weighs 14.5 lbs and the dimensions of the same are 17 x 14 x 3.8 inches.

Some of the key USPs of this whole house tankless water heater is listed below :

  • Can handle a water pressure range of 25 PSI to 150 PSI
  • Electric specifications are 240 volts, and 18 kW
  • Stainless steel construction
  • The output water flow of 3.5 GPM
  • 5 year and a 1-year warranty for leaks and parts respectively
PROS:
  • Installation instructions were clear
  • Easy to adjust the unit temperature
  • Very efficient
  • Great unit with reliable performance
  • Good value for money
CONS:
  • Some users complained the unit doesn’t heat the water enough

Check Reviews & Price on Amazon

15.best overall rating

Marey ECO150 220V/240V-14.6kW Tankless Water Heater with Smart Technology, Small, White

Marey ECO150 220V/240V-14.6kW Tankless Water Heater with Smart Technology, Small, White

Marey Company was founded in 1955 and they specialize in the design and manufacture of tankless water heaters. They offer affordable variants of both electrical and gas tankless water heaters.

The company was founded in Puerto Rico by an entrepreneur Mr. Mariano Reyes. Keeping their product line focused on tankless water heaters, they also sell parts and accessories for them and refurbish old models.

The electrical specifications of this unit are 220 V to 240 V and it requires a 70 AMP double pole breaker.

This water heater is an example of simple and smart technology in that it allows fine-tuning the temperature easily with the help of an LCD panel. This precision goes a long way in helping one to preserve electricity.

Constant temperatures are guaranteed by a flow switch activation mechanism. This enables the unit to maintain consistent temperatures with flows as low as 0.5 GPM/ 5 Psi.

This 10 lbs water heater supports a vertical wall mounting and the dimensions of this unit are 8.7 x 3.5 x 14.2 inches. The 150 in the ECO150 is descriptive of the power rating which stands at approximately 14.6 kW.

Some of the key USPs of this whole house tankless water heater is listed below :

  • ETL approved model
  • German-designed patented heating element with a stainless steel water channel
  • Comes with a 5-year warranty
PROS:
  • Rated high in energy efficiency
  • Impressive temperature control
  • Installation is fairly straightforward
  • Budget purchase
  • Good, reliable performance
  • Quality customer service by Marey
CONS:
  • Instruction quality could be better

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Buying Guide for Whole House Tankless Water Heater

Rinnai RL94EP Tankless Water Heater, Large, RL94eP-Propane/9.4 GPM

The following are some of the parameters that should be kept in mind when purchasing a tankless water heater for whole-house usage.

These are important because it is a long term investment and can significantly affect the ease and comfort of getting hot water instantly.

Unit Sizing

The residential tankless water heater should be sized specifically for the home’s hot water needs. Adequate capacity should be provided for optimal water supply and a delivery network.

Oversizing the unit works against the advantages of a tankless water heater.

All the manufacturers include a detailed guide on how to determine which model would be best suited to one’s needs depending upon the location they live, the climatic conditions, the temperature of groundwater, etc.

Accordingly, it is indicated which model can support how many faucets.

Installation space

The indoor and outdoor installation makes a great difference in the performance of the unit.

If one has a space crunch inside their house and would want to go for outdoor installation, one has to make sure that the unit is built for that.

These units would ideally have more weather protection or freeze insulation to avoid harsh climatic conditions from affecting the performance of the heater.

Similarly, a unit that is strictly built for indoor installation should be installed inside the house as it would not be equipped to function under the conditions prevailing outside of the house.

Smart Functions

Some of the water heaters these days are equipped with functionality like self-modulating systems that maintain the temperature and energy consumption according to the flow of the water.

There are also functions like wifi-enabled heaters, freeze protectors, etc. that make this device smart.

Flow Rate

One of the crucial aspects of any tankless water heater is the flow rate. Since it does not store water; the flow rate is the sole indicator of how much hot water output the unit can supply.

A higher flow rate is a direct indicator of a higher number of faucets that can be serviced. If one is looking at operating many faucets simultaneously, they should strictly consider the specifications manual that will give an idea of what each specific model can do.

Also, if one lives in cold weather conditions, there are special mentions of what model should be used in that case.

Energy efficiency

Given that a tankless water heater is going to be used almost every day and forms an essential component of day to day activities, it makes sense that one should ensure that it consumes electricity/ gas efficiently.

The water heaters are given a certification by energy star or contain some information regarding their energy-saving efficiency in their manuals.

One should carefully consider this information and also make sure that the device meets the local norms and regulations. This can amount to significant savings over time.

One of the last, but not the least factors, is the price. The tankless variety of water heaters is generally more expensive than the tanked versions.

However, this cost is neutralized over time with energy efficiency and the long life of the product.

One should keep their budget in mind but not skimp on the quality of the product as this is a one time, long term investment.

Benefits of Tankless Water Heater for Whole-House Usage

Stiebel Eltron 24 Plus Tempra, Tankless Water Heater, White

Some of the benefits of using a tankless water heater for whole-house usage are discussed below.

Space-Saving Design

Space efficient design of tankless heaters enables them to be placed strategically throughout the house and even outside to greatly reduce the lag time and the amount of water wasted in that process.

As opposed to this, a tank version of the water heater takes up a lot of space as it is bulkier in design and occupies more space as it has to store the water within.

Energy Efficiency

A tanked water heater has a certain amount of water inside it at all times and it is required to maintain that water at the temperature which is set by the user constantly.

What this implies is that a tanked water heater is always on and keeps consuming energy to maintain the water at a certain temperature and this leads to huge wastage.

As opposed to this, a tankless water heater essentially remains in the off state unless a faucet or an application demands water and a trickle are detected by the sensors.

These sensors are turned on only when the trickle has a certain minimum flow level.

Longer Life

When one is investing a few hundred dollars in buying a water heater, they expect the product to serve them purposefully over at least a few years.

This is one area where tankless water heaters do not disappoint. With proper care and maintenance, a tankless water heater can easily last for 20 to 25 years.

This makes it one of the most financially viable options for getting hot water supply around the house.

Space Consumption

Since, we are talking about residential or whole house usage, aesthetic is one of the factors that cannot be ignored.

Nobody would prefer having a huge, bulky tank visible and taking up a lot of space in the washroom or elsewhere in the house.

The tankless water heaters available these days rank high on the aesthetic appeal and successfully fit into small, strategic corners owing to their compact and sleek design.

The design has no impact on their performance whatsoever.

Time to Heat

In case of a tanked water heater, there are a few minutes before hot water can reach the faucet. This causes wastage of water as the user will let the cold water flow freely without using it until they get the required temperature.

In contrast, a tankless water heater can supply water instantaneously. This is because it is triggered as soon as it detects a flow of water in the system.

These are a few benefits of using a tankless water heater for whole-house usage.

Benefits and Limitations of Gas Tankless Water Heater for Whole-House Usage

Bosch Electric Tankless Water Heater - Eliminate Time for Hot Water - Easy Installation The benefits of a gas tankless water heater for whole-house usage are discussed below.

More Powerful

A gas tankless water heater is more efficient at the utilization of the energy supplied to it and is able to deliver better performance than an electric water heater of similar specifications.

The gas tankless water heaters are able to achieve higher temperatures quicker and while using lesser amount of energy.

Better Equipped to Deal with Cold Weather Conditions

Most tankless gas water heaters require ventilation due to the NOx emissions, however low they may be. Due to this, most of them are designed in a manner that they can be installed outside the house.

This makes tankless gas water heaters better equipped to deal with harsh climatic conditions and deliver hot water regardless of the outside temperatures which is something that is not guaranteed by tankless electric water heaters.

Environment-Friendly

Natural gas and liquid propane are fairly more environment friendly as compared to alternative fuels like petroleum or diesel. They have a significantly lesser carbon footprint (almost 50% lesser).

The little NOx emissions that these heaters have are also strictly regulated by the laws set by the state of California and are well within the permissible limits.

Higher Reliability

A gas supply line is a far more reliable source of energy than electricity. Many places experience power outrages and surges which make electric tankless water heaters a little unreliable for getting a constant supply of water.

As compared to this, a gas tankless water heater is a better option.

The limitations of a gas tankless water heater for whole-house usage are discussed below.

More Installation Requirements

A tankless water heater requires proper ventilation to function. This often requires rework and increased costs.

A properly trained technician is required to complete the installation process and the necessary equipment may also have to be purchased separately for ensuring a proper functioning.

Emissions

Electric tankless water heaters have no emissions, however, no matter how energy efficient gas tankless water heaters are; they will have some amount of NOx emissions which is not good for the environment.

Expensive

The gas water heaters are sometimes more expensive than the electric water heaters on the get-go. The installation charges are also higher owing to the need for having a proper ventilation system in place.

Benefits and Limitations of Electric Tankless Water Heater for Whole-House Usage

Bosch Electric Tankless Water Heater - Eliminate Time for Hot Water - Easy Installation

The benefits of an electric tankless water heater for whole-house usage are discussed below.

Pocket-Friendly

Electric water heaters are in general less expensive than gas water heaters. Electricity costs are also slightly less than gas consumption costs. There is no venting required so the rework costs are also negligible.

More Environment-Friendly

There are no emissions involved which is not the case with gas tankless water heaters. Therefore, when it comes to environment friendliness, electric water heaters are a better option.

Low Installation Costs

Since there are no special ventilation requirements that are associated with an electrical tankless water heater, there is a significant difference in the amount of costs required for installation of these two variants.

Electric tankless water heater emerges as the clear winner and a low cost option.

The limitations of an electric tankless water heater for whole-house usage are discussed below.

Installation location

Electric water heaters will generally not be able to withstand harsh weather conditions and aren’t designed in that manner either.

For this reason, they need to be installed inside the house and this might be an eyesore for some people who wouldn’t prefer having an indoor installation.

Added Costs of Rework

A professional installation is needed for electric tankless water heaters for the warranty to hold true. This also means that there might be need for rework to get the fittings done properly and install the heater in the current configuration.

Not very Effective in Cold areas

The electric water heaters are not very effective in cold climatic conditions. If the temperatures are too low, the heater would not be able to keep up a hot water supply for the entire house.

How to use Whole House Tankless Water Heater

To understand how to optimally use a residential tankless water heater, it is essential to get under the hood and look at how the heater works. The following few pointers highlight some important things to know.

A tankless water heater is also called an on-demand or continuous water heater. They are designed to provide hot water, when and only when it is called for.

Gas-based tankless water heaters lower water use by 20% and can save up to 60% of water heating energy. These numbers vary according to household usage and local utility factors.

Below, we take a brief look at the working of a propane whole house tankless water heater.

  • A whole-house tankless water heater uses a compact metal cabinet instead of a tank. Because there is no pre-heated or standby water to manage, there is no need to insulate the cabinet or maintain a level of heating energy.
  • So instead of being always on, a tankless water heater only uses energy when there is a demand for hot water.
  • Otherwise, it is effectively off. This accounts for the bulk of the energy savings and reduced emissions afforded by tankless water heaters.
  • When hot water is called for an appliance or a faucet, cold supply water flows into the unit. A sensor detects this flow triggering a computer-generated signal to send propane into the heating element and bring combustion air into the inducer motor.
  • The unit draws the combustion air usually from an intake at the top and exhausts it from the vent at the bottom.
  • Units installed inside the house require a sealed combustion direct vent pipe that both brings in and exhausts the combustion air safely from and to the outside.
  • The flow of propane triggers the furnace to ignite warming the heat exchanger. Some pipes curl around and through the heat exchanger heating the water as it flows.
  • The heater water is then supplied through the home’s plumbing system to the appliance or the faucet being used.
  • Once the tap is turned off, so does the unit and its energy demand and related energy cost.

This process allows a residential tankless water heater to supply an almost unlimited amount of hot water, even if more than one hot water-using appliance or fixture is on at a time.

Using a tankless water heater is a very simple process that only involves turning the faucet on when hot water is needed and initially setting a base temperature for the unit.

The rest of the process is taken care of by the heater itself.

Maintenance of Whole House Tankless Water Heater

Stiebel Eltron 29 Plus Tempra, Tankless Water Heater, White Most manufacturers recommend bi-annual maintenance activities for prolonging the life of a whole-house tankless water heater.

If one receives hard water in their region, the following are a few measures that can be taken to ensure the good health of the unit.

  • Using water softeners can be a good idea. These can be used before the water passes through the tankless heater.
  • Regular flushing with water or vinegar will help remove the limescale buildup. If this buildup is not cleared out, there is a chance of it breaking off and clogging the faucets.
  • The anode rod is a component of the water heater that attracts the calcium deposits onto itself and in the process protects the heat exchanger and other important components from corrosion. This rod should be checked and replaced as and when required.
  • The other aspect of conducting proper maintenance activities is to ensure that all the connections are in place properly. The electrical connections should be wired properly and tightly. The grounding should also be checked.
  • In the case of gas connections, it should be ensured that the pipe is not damaged in any way and that there are no leakages. This could be very dangerous and should be prevented. The ventilation system should also be checked regularly.

FAQs

How does a Tankless Water Heater Heat the Water Instantly?

The availability of instant hot water in case of whole house tankless water heaters can be owed to the smart automatic ignition systems that they come equipped with.
The heater gets powered on as soon as it detects a flow of water when the faucet is turned on (even as low as 0.2 GPM). This allows the heater to start its heating operations immediately.
The system also powers down on its own when the faucet is turned off and the water flow stops.

What are the Benefits of using a Whole House Tankless Water Heater?

A whole-house tankless water heater is useful because it can serve many faucets and showerheads comfortably at the same time without any reduction in its performance. The heater ensures optimal utilization of electricity or gas (whichever applicable) and therefore, reduces the cost of operations.
In its place, if multiple heaters are installed in the house, it leads to an increase in the consumption of gas, electricity, money, time and efforts in terms of maintenance and upkeep activities.
Since the water heater is tankless there is no need of wasting energy to heat the stored water inside the tank and also the user does not have to wait a significant amount of time before they can get hot water.

What Should be done if I Get Hard Water?

Almost all the models of whole house tankless water heaters come pre-installed with an anode rod. This sole purpose of this rod is to attract the minerals towards itself so it doesn’t have any corrosive effect on the heat exchanger. Along with this mechanism, regular flushing with vinegar or plain water can also help in removing calcified deposits that may have formed.
Regular maintenance activities are more than enough to prolong the life of the tankless water heater even if one gets hard water supply at their house.

How to identify the Correct Size of the Whole House Tankless Water Heater for my house?

The first and foremost step should be to identify the total number of faucets and showerheads in all the rooms of the household. The next step would be to check the specifications of the model which is being considered. All manufacturers give details of how many faucets the unit can support in different weather conditions. They also provide a sizing guide in many cases to help one get a fair idea of which unit would be best suited to fulfill their needs.

Can Existing Venting be used for a New Whole House Tankless Water Heater?

It is recommended that one use venting that is specified by the manufacturer for that particular tankless water heater. It is not good practice to use the existing venting if that is not conducive to the new unit.

Who can Install a Whole-House Tankless Water Heater?

All the whole house tankless water heaters come with an installation guide. This guide can make it fairly straightforward for any layman to read and install the heater. However, when it comes to gas tankless water heaters, there is also the case for adequate ventilation requirements.
In almost all cases, when the manufacturer offers a warranty on the unit, it is explicitly mentioned that the unit should be necessarily installed by a licensed professional for the warranty to be valid.
Since the unit is dealing with electricity/ gas and hot water, it is often best practice to leave the installation to professionals to ensure that all the safety requirements are taken care of.

How much Maintenance is Required for a Whole House Tankless Water Heater?

A bi-annual check of the components inside the whole house tankless water heater is useful for keeping a tab on the health of the unit. Activities like flushing can be undertaken to prolong the life of the unit. Apart from these, inspection helps in deciding when to replace or repair the parts of the heater preemptively.

Can one get Hot Water even if the Power is out?

In the case of electric tankless water heaters, one cannot get hot water if the power is out. However, in case of gas tankless water heaters, there is often a batter backup ignition option that will allow the heater to run despite power outrage. Once ignited, the hot water is supplied owing to the natural gas or liquid propane inside the heating unit.

What is Temperature Rise?

A temperature rise is the difference between the temperature that is set for the tankless water heater and that of the water coming from the inlet valve. The smaller this difference, the hotter water the unit will be able to produce instantly.
For example, if the temperature set on the tankless water heater is 120 and the temperature of the incoming water is 70, the temperature rise is 50. The ideal situation for optimally producing hot water would be to have a high temperature of the incoming water and a low-temperature setting of the tankless water heater.

How does Recirculation Work?

Recirculation is water and energy-saving mechanism. There is a sensor located near each faucet that activates this recirculation pump. The pump has a temperature sensor and a valve that prevents the ambient water from flowing into the return line. Once the hot water has reached the faucet, the pump is alerted of the same and it promptly shuts down saving energy and preventing unnecessary wastage of water or electricity/ gas.

Final Words

As is the case with most products, there is no one size fits all concept when it comes to tankless water heaters for whole-house usage.

There are a variety of models available, each with its unique features and specifications by several reputed manufacturers.

The best way to ensure that one is happy with their whole house tankless water heater is to choose the right size according to the requirements of the household.

As this is a significant expense as far as household expenses go, many manufacturers are willing to help and extend support to potential customers in choosing the correct model by providing a sizing guide.

One of the key things to keep in mind is the fact that, more often than not, the total costs involved in getting a tankless water heater for whole-house usage will not just include the purchase price of the unit.

There is almost always some sort of minor or major rework involved in the switch to tankless water heaters.

Therefore, careful thought and consideration is a must for getting the best value out of the unit which is purchased.

Here is the list of our top picks again for you. Check out the specs, customer reviews, price and offers on Amazon –

 

Last update on 2020-01-18 / Affiliate links / Images from Amazon Product Advertising API

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