Whole House Tankless Water Heaters Buying Guide

Updated October 2016. As technology continues to improve, tankless water heaters are becoming more efficient and increasingly popular. We delved into the world of tankless water heaters to find out which models are the most popular and which ones earned the highest ratings from consumers.  We researched both electric and natural gas models to identify the very best ones available on the market today.

When considering a tankless water heater, be sure to take note of the specifications so you end up with a water heater that is powerful and efficient enough for your needs, as well as compatible with your plumbing and other utility configurations.

We focused on whole house tankless water heaters for this buying guide, as opposed to point-of-use units. Within that category, there is still a wide range of options and capacities available. Read on for the details of what we discovered in our buying guide.

Highest rated whole house tankless water heaters on Amazon

Best rated tankless water heaters at AmazonCustomers on Amazon gave the highest rating to a water heater by Rheem. The other two tankless water heaters that received similar ratings are units from Seisco and Rinnai. Following closely behind in the Amazon ratings are several water heaters from Takagi and a few models by Stiebel.  Another Rheem tankless unit is next in line, and the highest rated list is completed with four  offerings from EcoSmart and another Steibel unit.

Rating Model
4.9 Rheem RTG-64XLN 6.4 GPM Low NOx Outdoor Tankless Natural Gas Water heater
4.9 SEISCO RA-28 Tankless Electric Water Heater
4.9 Rinnai V65EP 6.6 GPM Outdoor Low NOx Tankless Propane Water Heater
4.8 Takagi T-KJr2-IN-NG Indoor Tankless Water Heater, Natural Gas
4.8 Stiebel Eltron Tempra 20 Plus Electric Tankless Whole House Water Heater, 240 V, 19.2 kW
4.8 Takagi T-H3-DV-N Condensing High Efficiency Natural Gas Indoor Tankless Water Heater, 10-Gallon Per Minute
4.7 Stiebel Eltron Tempra 24 Plus Electric Tankless Whole House Water Heater, 240 V, 24 kW
4.7 Takagi T-T-KJr2-OS-LP Outdoor Tankless Water Heater, Propane
4.6 Takagi T-KJr2-IN-LP Indoor Tankless Water Heater, Propane
4.6 Rheem RTG-84XLN 8.4 GPM Low NOx Outdoor Tankless Natural Gas Water Heater
4.5 Ecosmart ECO 18 Electric Tankless Water Heater, 18 KW at 240 Volts with Patented Self Modulating Technology
4.5 Ecosmart ECO 24 24 KW at 240-Volt Electric Tankless Water Heater with Patented Self Modulating Technology
4.4 EcoSmart ECO 11 Electric Tankless Water Heater, 13KW at 240 Volts with Patented Self Modulating Technology
4.3 Ecosmart ECO 27 Electric Tankless Water Heater, 27 KW at 240 Volts with Patented Self Modulating Technology
4.3 Stiebel Eltron Tempra 29 Plus Electric Tankless Whole House Water Heater, 240 V, 28.8 kW

Bestselling whole house tankless water heaters on Amazon

Top selling tankless water heaters on AmazonLooking at sales data, Amazon customers favored units from Ecosmart much more than any other manufacturer of tankless water heaters; three of their models dominate the top of the best selling chart. Next in line is a Stiebel unit, followed by yet another Ecosmart model.  A Takagi water heater is next on the list, followed by a string of six Rinnai tankless units.  Finishing off the top seller list on Amazon are offerings from Stiebel and Bosch.

Rank Model
1 Ecosmart ECO 27 Electric Tankless Water Heater, 27 KW at 240 Volts with Patented Self Modulating Technology
2 Ecosmart ECO 18 Electric Tankless Water Heater, 18 KW at 240 Volts with Patented Self Modulating Technology
3 Ecosmart ECO 24 24 KW at 240-Volt Electric Tankless Water Heater with Patented Self Modulating Technology
4 Stiebel Eltron Tempra 24 Plus Electric Tankless Whole House Water Heater, 240 V, 24 kW
5 Ecosmart ECO 36 36kw 240V Electric Tankless Water Heater
6 Rinnai RL94eP Propane Tankless Water Heater, 9.4 Gallons Per Minute
7 Takagi T-K4-IN-LP Indoor Tankless Water Heater, Propane
8 Rinnai RL94iN Natural Gas Tankless Water Heater, 9.4 Gallons Per Minute
9 Rinnai V65EN 6.6 GPM Outdoor Low NOx Tankless Natural Gas Water Heater
10 Rinnai V65IP 6.6 GPM Indoor Low NOx Tankless Propane Water Heater
11 Rinnai V65EP 6.6 GPM Outdoor Low NOx Tankless Propane Water Heater
12 Rinnai RUC98iP Ultra Series Propane Tankless Water Heater, Concentric/Twin Pipe Installation
13 Rinnai RUC98iN Ultra Series Natural Gas Tankless Water Heater, Concentric/Twin Pipe Installation
14 Stiebel Eltron Tempra 29 Plus Electric Tankless Whole House Water Heater, 240 V, 28.8 kW
15 Bosch 520 PN LP Therm Tankless Water Heater, Propane

Bestselling whole house tankless water heaters at AJ Madison

Most popular tankless water heaters at AJ MadisonLooking at the most popular or best-selling tankless water heaters from AJ Madison, we see three units from Electrolux. The most popular unit is the Electrolux EP18W130LS water heater.

Rank Model
1 Electrolux EP18WI30LS
2 Electrolux EP19WI30LS
3 Electrolux EN18WI30LS

Bestselling whole house tankless water heaters at Wal-Mart

Top Rated tankless water heaters at WalmartTaking a look at the top selling data from Wal-Mart, we find the most popular tankless water heater is a model from Stiebel. The next best-selling whole house tankless water heater at Walmart is an EcoSmart unit. Takagi, Marey and Rheem models follow up next on the bestsellers list. After that we see units from EchoSmart and Powerstar. Three more Rheem water heaters are next up, after which is a Takagi unit. The list is finalized with three other Rheem units and one more water heater from Takagi.

Rank Model
1 Stiebel Eltron TEMPRA 15 Whole House Tempra Tankless Water Heaters Electric
2 EcoSmart ECO27 27 kW 240V Electric Tankless Water Heater
3 Takagi T-KJr2-IN-NG Whole House Tankless Water Heaters Gas/Propane
4 Marey 5.4 GPM Tankless Liquid Propane Hot Water Heater ETL Approved GA16LPETL
5 Rheem RTG-84DVLN Direct Vent Natural Gas Tankless Water Heater for 2 – 3 Bathroom Homes
6 EcoSmart ECO18 18 kW 240V Electric Tankless Water Heater
7 PowerStar AE115 Whole House Electric Tankless Water Heater
8 Rheem RTG-64XLN Outdoor Natural Gas Low Nox Tankless Water Heater for 1 – 2 Bathroom Homes
9 Rheem RTG-64DVLN Direct Vent Low Nox Natural Gas Tankless Water Heater for 1 – 2 Bathroom Homes
10 Rheem RTG-64XLP Outdoor Tankless Propane Water Heater for 1 – 2 Bathroom Homes
11 Takagi T-KJR2-IN-LP Whole House Flash Tankless Water Heaters Gas/Propane ;Liquid Propane
12 Rheem RTG-95DVLN Direct Vent Low Nox Natural Gas Tankless Water Heater for 2 – 3 Bathroom Homes
13 Rheem RTG-95DVLP Direct Vent Low Nox Liquid Propane Tankless Water Heater for 2 – 3 Bathroom Homes
14 Takagi T-K4-IN-NG Whole House Tankless Water Heaters Gas/Propane
15 Rheem RTGH-84DVLN 8.4 GPM Direct Vent Tankless Water Heater (NG)

Conclusion

A theme we noticed when researching tankless water heaters for this buying guide is that each retailer appears to have a few brands they favor over the others. One of the more successful manufacturers across multiple outlets is Rheem. Others are Stiebel and EcoSmart. When choosing a tankless water heater for your home, be sure to take a look at the specifications to ensure it will provide adequate hot water for the size of your home. Also, take into consideration how heavy of use the unit will receive based on your needs. Finally, because we covered both Gas and Electric water heaters in our buying guide, be sure to focus on the format you need for your space.