A shower is one of life’s small luxuries, and a hot one, with soothing music or in blissful silence, is a great way to relax. The most popular water heating equipment for the job is a gas water heater, which uses gas energy to make hot water.
Gas tankless water heaters heat water on demand, so you never run out, and they are generally more efficient than tank heaters. The units are easy to install if you already have a gas line in the right place. Below we compare six gas tankless water heaters, from budget models to a premium condensing unit, followed by a short guide on how to choose.
| Product | Our Rating | ||
|---|---|---|---|
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Best overall
Rheem RTG Series 7.0 GPM Natural Gas Tankless Water Heater, Indoor, 160,000 BTU |
VIEW ON AMAZON | |
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Best for large families
Rheem RTG Series 8.4 GPM Natural Gas Tankless Water Heater, Outdoor, 180,000 BTU |
VIEW ON AMAZON | |
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Best budget capacity
Ranein Natural Gas Tankless Water Heater, 8.5 GPM, 190,000 BTU, Indoor |
VIEW ON AMAZON | |
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Best budget
APUS Natural Gas Tankless Water Heater, 95,000 BTU, 4.42 GPM, Indoor |
VIEW ON AMAZON | |
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Premium pick
Rinnai RX199iN Condensing Smart Sense Tankless Water Heater (Indoor or Outdoor, Natural Gas or Propane) |
VIEW ON AMAZON | |
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Best for propane
Rinnai V53DeP Propane Tankless Water Heater, 5.3 GPM, Outdoor |
VIEW ON AMAZON |
Best Gas Tankless Water Heater Reviews in 2026
Best Natural Gas Tankless Water Heaters
1. Rheem RTG Series 7.0 GPM Natural Gas Tankless Water Heater, Indoor, 160,000 BTU
The Rheem RTG Series 7.0 GPM is a whole-house, non-condensing natural gas tankless heater for indoor installation with a direct vent system. It delivers 7.0 GPM at a 35 degree temperature rise, which is enough for two to three showers at once, and it has a 0.82 uniform energy factor.
- 7.0 GPM at 35 degree rise, 160,000 BTU
- Indoor installation with direct vent
- Non-condensing, 0.82 UEF
- Whole-house natural gas model
- Enough capacity for two or three showers at the same time
- Rheem is a major, widely supported brand
- Energy savings compared with a 50-gallon electric tank
- A very good price for whole-house capacity
- Strong owner feedback
- Non-condensing, so less efficient than the premium condensing models
- Needs venting and a gas line that can handle the load
Our Verdict: Our top pick: strong capacity, a trusted brand and a sensible price for an average family home.
2. Rheem RTG Series 8.4 GPM Natural Gas Tankless Water Heater, Outdoor, 180,000 BTU
This is the outdoor version of Rheem’s larger RTG heater. It delivers 8.4 GPM at a 35 degree temperature rise from 180,000 BTU per hour, enough for three to four showers at once, and installing it outdoors eliminates the need for venting.
- 8.4 GPM at 35 degree rise, 180,000 BTU
- Outdoor installation, no venting needed
- Non-condensing, 0.82 UEF
- Whole-house natural gas model
- Top owner rating in the group
- Outdoor installation avoids venting and saves indoor space
- Large capacity for big families or several bathrooms
- Backed by Rheem's service network
- Costs more than the indoor 7 GPM model
- In very cold climates the outdoor location needs freeze protection
Our Verdict: The best heater for a large family, where an outdoor installation is possible.
3. Ranein Natural Gas Tankless Water Heater, 8.5 GPM, 190,000 BTU, Indoor
The Ranein is a large-capacity indoor natural gas heater rated at 8.5 GPM and 190,000 BTU. Its fan sits underneath to improve safety and prevent smoke backflow, and the blower automatically adjusts speed according to wind pressure and water temperature so combustion stays complete.
- 8.5 GPM, 190,000 BTU natural gas
- Indoor installation
- Blower adjusts automatically for safe combustion
- No 30-minute preheating wait
- High capacity at a lower price than the big brands
- Fan design adds safety against backflow
- Low noise and a long service life are claimed
- Large owner base for a lesser-known brand
- Brand is less established than Rheem or Rinnai, so support is less certain
- Owner ratings are lower than for the leaders
Our Verdict: A budget-friendly high-capacity option if you can accept a lesser-known name.
4. APUS Natural Gas Tankless Water Heater, 95,000 BTU, 4.42 GPM, Indoor
APUS offers a compact 95,000 BTU heater at 4.42 GPM that is meant for two showers plus a sink. It has a low-flow start of 0.66 GPM, a smart CPU with high-precision sensors that keeps the temperature within one degree of the set value, and an adjustable range of 95 to 140 degrees F.
- 95,000 BTU, 4.42 GPM natural gas
- Low-flow start at 0.66 GPM
- Holds temperature within +/-1 degree F
- Adjustable from 95 to 140 degrees F
- The lowest price in the roundup
- Good for small to medium homes with two showers
- Precise temperature control
- Starts at a very low flow, so small taps work too
- Smaller capacity than the whole-house leaders
- Brand is newer, with limited support history
Our Verdict: The cheapest way into gas tankless for small homes and apartments.
Best Premium and Propane Tankless Water Heaters
5. Rinnai RX199iN Condensing Smart Sense Tankless Water Heater (Indoor or Outdoor, Natural Gas or Propane)
The Rinnai RX199iN is a condensing heater that can be installed either indoors or outdoors, using Rinnai’s Versa Vent, and it runs on either natural gas or propane thanks to a Smart Sense gas control. About the size of a small suitcase, it delivers up to 11.1 GPM, enough for as many as seven fixtures at once.
- Condensing, up to 11.1 GPM
- Indoor or outdoor installation with Versa Vent
- Natural gas or propane via Smart Sense
- Easy-to-use interface and Quick Flush feature
- Very high capacity for large homes
- Condensing design is more efficient than non-condensing models
- One model for any location and either fuel
- Compact for its power, with an easy interface
- Top-rated by owners
- The most expensive heater in the roundup
- Outdoor installs need an RX-OVC vent cap, which is sold separately
Our Verdict: The premium choice for efficiency and flexibility, if you can afford it.
6. Rinnai V53DeP Propane Tankless Water Heater, 5.3 GPM, Outdoor
The Rinnai V53DeP is a compact outdoor propane tankless heater with a 5.3 GPM flow rate. It supplies endless hot water to several fixtures, conserves energy by heating only on demand and includes improved scale detection to protect the unit, and its small size suits tight spaces.
- 5.3 GPM flow rate, propane
- Outdoor installation
- Scale detection feature
- Compact, space-saving design
- A good choice for homes without natural gas
- Trusted Rinnai quality and service
- Compact for installation in tight spots outdoors
- Scale detection helps protect the heat exchanger
- Smaller capacity than the Rheem models
- Propane only, so not usable with natural gas
Our Verdict: The best option for propane homes or cabins.
Gas Tankless Water Heater Prices and Efficiency
Prices span a wide range. Cheap units start from around $150 to $500, but it is wise not to buy the cheapest unit available, because those can bring trouble. Mid-range heaters of $500 to $1,000 give 5 to 9 GPM and are enough for most homes. Premium units from about $1,500 to $2,500 are condensing, with efficiencies of around 90 to 96 percent compared with about 80 to 86 percent for an average gas tankless unit, and they can supply up to 15 GPM or more.
Most manufacturers offer warranties, often split into one for the heat exchanger and one for the other parts. Some are valid only if a professional installs the heater, and some do not cover commercial use, so read the terms.
Gas vs. Electric Tankless Water Heaters
One of the biggest advantages of gas over electric is that natural gas is cheaper than electricity, but gas is a non-renewable fuel and its price may rise in future. It cannot be said that gas is simply superior to electric, so compare them against your own requirements. Our guide gas vs electric tankless water heater goes into detail, and you can also read our electric tankless water heater reviews.
How to Choose a Gas Tankless Water Heater
- Flow rate. Add up the GPM of the fixtures you will run at the same time and choose a heater that can deliver that at the temperature rise you need in winter.
- Fuel type. Check whether you have natural gas or propane, because many models are fuel-specific.
- Indoor or outdoor. Outdoor models do not need venting but must be protected from freezing. Indoor models need a vent.
- Condensing or non-condensing. Condensing units are more efficient but cost more and need a drain for the condensate.
- Gas line and venting. A bigger heater needs a larger gas line. Have a professional check this before you buy.
- Warranty and support. Pick a brand with a good service network.
Read reviews to compare the written specifications with the real experience of owners, and avoid the very cheapest units. Relax, take your time, research, and make a smart investment. See also our portable tankless water heater reviews.
