A gas tankless heater burns natural gas or propane as water flows through it. The biggest residential models reach 199,000 BTU/h, enough for two or three showers at once in most climates. Condensing models pull extra heat from the exhaust, score higher on efficiency and vent through PVC; non-condensing models cost less but need stainless steel venting. Most models come in a natural gas and a propane version, which share one listing here.
Prices were last checked October 31, 2026 and are subject to change; the price and availability shown by the retailer at the time of purchase apply.
Full ranking 20
- Rinnai Sensei RX199i#1 of 20Full review
A top choice for a large home that wants one heater for three or more showers at once with the lowest gas bills Rinnai offers.
Amazon $1,532.79$1,532.79199,000 BTU/h11 GPM0.98 - Rheem RTGH-95DV#2 of 20Full review
A well priced condensing whole home heater for buyers who want PVC venting and lower gas bills.
Amazon $1,411.70 Amazon $1,411.99$1,411.70199,900 BTU/h9.5 GPM0.93 - Eccotemp 7GB Builder Grade#3 of 20Full review
A strong value outdoor heater for a natural gas home in a mild climate, with a better warranty than most budget rivals.
Amazon $499$499180,000 BTU/h7 GPM- - Rheem RTG-95DV#4 of 20Full review
A whole home indoor heater for buyers who want maximum burner size without the condensate drain of a condensing unit.
Amazon $1,201.29$1,201.29199,900 BTU/h9.5 GPM0.82 - Rheem RTG-70DV#5 of 20Full review
A budget indoor heater from a major brand for a two bathroom home in a moderate climate.
Amazon $653.77 Amazon $785.13$653.77160,000 BTU/h7 GPM0.82 - ThermoMate CZ750NG#6 of 20Full review
A low cost indoor whole home heater for natural gas homes, but check the warranty with ThermoMate before buying.
Amazon $739.99$739.99199,000 BTU/h8 GPM0.81 - Rheem IKONIC S11i#7 of 20Full review
A premium condensing heater for a large home that wants top efficiency and app control from one unit.
Amazon $1,847.43 Amazon $1,859.99$1,847.43199,900 BTU/h11.2 GPM0.96 - Gasland Gasmart E CE686#8 of 20Full review
A low priced whole home heater for buyers who accept a short warranty and thin documentation to save several hundred dollars.
Amazon $629.99 Amazon $629.99$629.99199,000 BTU/h7.6 GPM0.80 - Rinnai RE199e#9 of 20Full review
A strong pick for homes in mild climates that want full whole home power without running a vent.
Amazon $1,280.79 Amazon $1,280.79$1,280.79199,000 BTU/h9.8 GPM0.82 - Rinnai RE199i#10 of 20Full review
A dependable whole home heater for buyers who want Rinnai power at a lower price than a condensing model and have room for metal venting.
Amazon $1,280.79 Amazon $1,412.82$1,280.79199,000 BTU/h9.8 GPM0.82 - Camplux WA686M#11 of 20Full review
A bargain outdoor whole home heater for mild climates, best for buyers comfortable with a short warranty.
Amazon $559.99 Amazon $599.99$559.99199,000 BTU/h8.4 GPM- - Rinnai Sensei RX160i#12 of 20Full review
A very efficient heater for a two bathroom home that does not need the full 199,000 BTU/h of the RX199i.
Amazon $1,298.43$1,298.43160,000 BTU/h9 GPM0.97 - A.O. Smith Adapt ATHR-199M#13 of 20Full review
A premium whole home heater for buyers who want built in recirculation and top efficiency and can pay for it.
Amazon $2,346.08$2,346.08199,000 BTU/h10.5 GPM0.95 - Camplux Climatech 7 CA686W#14 of 20Full review
A low cost indoor heater for a two bathroom home where price matters more than a long warranty.
Amazon $629.12$629.12170,000 BTU/h6.9 GPM- - ThermoMate RTC68iN#15 of 20Full review
A budget condensing heater for natural gas homes that want PVC venting and lower gas bills, if you can live with an unclear warranty.
ThermoMate $1,099.99$1,099.99163,000 BTU/h9.4 GPM0.91 - Mizudo GEN 3 199K#16 of 20Full review
A connected indoor heater with full whole home power, though major brands give a longer warranty for similar money.
Amazon $1,199 Amazon $1,199$1,199199,000 BTU/h10.3 GPM- - Rinnai RE140e#17 of 20Full review
A good outdoor heater for a one or two bathroom home in a mild climate.
Amazon $884.10 Amazon $884.10$884.10140,000 BTU/h5.3 GPM0.81 - Eccotemp SmartHome SH22i#18 of 20Full review
An affordable smart heater for a small home that wants app control without paying for a premium brand.
Amazon $499 Amazon $499$499140,000 BTU/h6.8 GPM- - Rinnai V53De#19 of 20Full review
A low cost outdoor heater from a major brand for a small home, cabin or condo in a mild climate.
Amazon $741.65 Amazon $741.65$741.65120,000 BTU/h5.3 GPM0.81 - Noritz NRC661-DV#20 of 20Full review
A compact condensing heater for a smaller home that wants PVC venting, though bigger rivals cost little more.
Amazon $1,280.09 Amazon $1,470.40$1,280.09120,000 BTU/h6.6 GPM0.89
