Finding the best gas water heater for the money means balancing hot-water capacity, installation needs, efficiency, and the cost of getting the unit set up correctly. The five picks below are all natural-gas tankless models, but their flow rates, installation styles, and listed features differ. Before choosing one, check your home’s incoming water temperature, gas supply, venting, and local code requirements with a qualified installer.
Table of Contents
Quick Comparison
| Product | Listed capacity | Installation | Notable feature |
|---|---|---|---|
| Rheem RTG Series 7.0 GPM | 7.0 GPM; 160,000 BTU | Indoor, direct vent | Leak detection and temperature control |
| ThermoMate CZ422NG | Up to 5 GPM; 102,000 BTU | Indoor | Compact size and diagnostic display |
| Rinnai V53DeN | 5.3 GPM | Outdoor | Compact design and listed heat-exchanger warranty |
| Rinnai RE160iN | Up to 6.6 GPM; 160,000 BTU | Confirm exact model and venting | Service reminders and error codes |
| GASLAND Gasmart E | Up to 5.8 GPM; 150,000 BTU | Indoor | Listed UEF of 0.8 |
Flow rates are not directly comparable unless they use the same temperature-rise conditions. Your home’s groundwater temperature and desired output temperature affect how much hot water a tankless unit can deliver at once.
Our Picks: Best Gas Water Heater For The Money reviews
1. Rheem RTG Series: A high-capacity pick for busy homes
The Rheem RTG Series is an indoor, non-condensing natural-gas tankless heater designed for whole-home use. Its listed output is 160,000 BTU per hour, with a rated 7.0 GPM at a 35°F temperature rise. That combination makes it the highest-capacity option in this group on paper, though actual performance depends on your incoming water temperature and the installation.
Useful features include a digital temperature control with stated one-degree adjustments, built-in freeze protection, and LeakGuard leak detection and prevention. The unit is wall-mounted, so it can free up floor space compared with a tank. Its indoor direct-vent setup also means you need to plan carefully for compatible venting and clearances.
This is a strong candidate for a larger household that may run several hot-water fixtures at once. The product information lists a UEF of 0.82 and claims energy savings compared with a 50-gallon electric tank, but actual savings depend on your usage, utility rates, and existing heater. The supplied listing is marked unavailable, so confirm that the product can be purchased before building your project around it.
Pros:
- Highest listed flow rate in this comparison
- Designed for whole-house use and multiple simultaneous fixtures
- Leak detection and several built-in safety features
- Wall-mounted design saves floor space
Cons:
- Indoor direct-vent installation requires careful planning
- Availability may be limited; confirm the listing before purchasing
Verdict: Choose the Rheem if you need strong listed capacity for a busy home and can confirm availability and a suitable indoor venting setup.
2. ThermoMate CZ422NG: A compact indoor option with clear diagnostics
The ThermoMate CZ422NG is an indoor natural-gas tankless heater rated for up to 5 GPM and 102,000 BTU. The listing describes its two-shower capacity at a specific example condition: 105°F output with 65°F incoming water. That context matters, since colder inlet water can reduce the flow available at your chosen temperature.
Its compact listed dimensions are 21 inches high, 13 inches wide, and 7 inches deep. A 3.5-inch LED display shows temperature and operating information, while error codes are intended to help with troubleshooting. The product also lists freeze protection and a range of other safety protections. The maker claims up to 98% thermal efficiency and a UEF of 0.81; those are manufacturer-provided specifications, not a guarantee of a particular utility-bill reduction.
This model may suit a smaller household or a home with moderate simultaneous hot-water demand. Its indoor design requires correctly sized gas and water connections, electrical power, and compatible venting. The listing gives connection details, but an installer should verify that they match your home and local requirements.
Pros:
- Compact indoor design with a useful diagnostic display
- Lists up to 5 GPM and 102,000 BTU of output
- Includes freeze protection and multiple stated safety protections
- Lists temperature adjustment from 90°F to 140°F
Cons:
- Less listed capacity than the higher-output Rheem and Rinnai options
- Actual flow depends on the temperature rise and household demand
Verdict: The ThermoMate is worth considering if you want a compact indoor unit with diagnostic features and your home’s hot-water demand fits its capacity.
3. Rinnai V53DeN: An outdoor model for homes with suitable space
The Rinnai V53DeN is a natural-gas tankless water heater intended for outdoor installation. It has a listed flow rate of 5.3 GPM and is described as serving up to four appliances. That figure is not a promise that all four can run at once at full flow; the result will depend on the fixtures’ demand and the temperature rise needed in your location.
Outdoor placement can avoid the need to route an indoor vent through the home, but it requires an appropriate exterior location and installation that follows the manufacturer’s instructions and local code. The compact design may help where indoor utility space is tight. The listed residential warranty provides a 15-year limited warranty on the heat exchanger, five years on parts, and five years on labor, with registration within 90 days required for the stated labor term.
This pick is best for homeowners who specifically want an outdoor unit and have a suitable installation location. Compared with the higher-capacity models here, the V53DeN has a lower listed flow rate, so it may be a better fit for moderate household demand than for several high-flow fixtures running together.
Pros:
- Outdoor installation can preserve indoor utility space
- Listed 5.3 GPM flow rate for household hot-water use
- Compact design
- Listed residential warranty includes heat-exchanger, parts, and labor coverage
Cons:
- Outdoor installation limits where the unit can be placed
- Lower listed flow rate than the largest-capacity options in this group
Verdict: Pick the V53DeN if you want a compact outdoor heater and its listed capacity suits your home’s likely peak demand.
4. Rinnai RE160iN: Higher listed output with service reminders
The Rinnai RE160iN is listed at up to 6.6 GPM and 160,000 BTU, putting it among the higher-output choices here. The product information says it can serve up to five fixtures at once, but the usable number will depend on the temperature rise and the flow each fixture needs. It heats water on demand and includes an LED screen with service reminders and error codes.
One important detail needs checking before you buy: the product title identifies the RE160iN, while the supplied description calls the unit an outdoor model. Because indoor and outdoor models have different venting requirements, confirm the exact model number, installation type, and approved venting in the current product documentation before ordering.
The listed residential warranty is 15 years for the heat exchanger, five years for parts, and five years for labor, with registration within 90 days required for the stated labor coverage. Wi-Fi control is not included; the listing says a separate Controlr module is needed. Professional installation is recommended, which is especially important given the need to verify the model and vent configuration.
Pros:
- Strong listed capacity of up to 6.6 GPM and 160,000 BTU
- Service reminders and error codes on the LED screen
- Listed warranty covers the heat exchanger, parts, and labor
- Designed to heat water only when needed
Cons:
- Product information conflicts on whether the model is indoor or outdoor
- Wi-Fi control requires a separate module
Verdict: Consider the RE160iN for its listed capacity, but do not purchase until the seller or manufacturer confirms the exact model and installation configuration.
5. GASLAND Gasmart E: A mid-to-high-capacity indoor option
The GASLAND Gasmart E is an indoor natural-gas tankless heater listed at up to 5.8 GPM and 150,000 BTU. Its product information describes it as a whole-house model with a compact, wall-mounted design. As with the other heaters, the maximum flow figure does not tell the whole story: colder incoming water or multiple high-demand fixtures can reduce available flow.
The unit is listed as CSA certified and includes stated overheat, flame-out, and freeze protections. Its listed UEF is 0.8. The maker also describes a one-year replacement promise if the heater stops working within that period; check the written warranty for exclusions, coverage details, and any installation requirements before relying on that promise.
This model could suit a household looking for more listed capacity than the ThermoMate while avoiding the largest unit in the comparison. It is an indoor appliance, so you will need an approved venting plan and a professional check of gas-line capacity. The listing’s efficiency and savings claims should be treated as manufacturer claims rather than a guarantee of your own operating costs.
Pros:
- Listed flow rate of up to 5.8 GPM and output of 150,000 BTU
- Compact wall-mounted design
- CSA certification and several stated safety protections
- Listed UEF of 0.8
Cons:
- Indoor venting and gas-supply needs can add installation work
- Warranty terms should be checked carefully before purchase
Verdict: The Gasmart E is a reasonable option to compare if you want an indoor unit with more listed capacity than a smaller 5-GPM model, provided its installation requirements fit your home.
How to Choose a Gas Tankless Water Heater
Match flow rate to your household’s peak use
Think about how many hot-water fixtures may run at the same time, such as showers, a dishwasher, or a washing machine. Add their approximate flow needs, then compare that demand with the heater’s output. A listed maximum GPM is not a guarantee at every temperature, so look for the temperature-rise conditions behind the rating. When those conditions are not given, ask the manufacturer or installer for a sizing recommendation.
Account for incoming water temperature
A tankless heater must raise cold water to your chosen output temperature. If your incoming water is cold, the unit has to work harder, and the flow it can heat may fall. A model that handles your needs in a warm climate may not provide the same flow in a colder region. Use local groundwater-temperature information and the manufacturer’s sizing guidance when comparing units.
Confirm indoor or outdoor installation
Indoor units need venting that is approved for the specific heater and suitable for your home. Outdoor units need a safe, permitted exterior location and must be installed according to the product instructions and local rules. Do not assume two models from the same brand use the same setup. Verify the complete model number and venting type, especially when the product listing gives conflicting information.
Check gas, water, electrical, and vent connections
Before choosing a heater, have a qualified professional check whether your gas line can supply the required input and whether your existing water, vent, and electrical connections are compatible. A new tankless unit may require changes to these systems. The product’s connection sizes and power requirements should be compared with your home rather than treated as a guarantee of simple installation.
Compare efficiency claims carefully
Uniform Energy Factor (UEF) can help you compare models, but it does not tell you exactly how much you will save. Your hot-water habits, local gas and electricity rates, climate, and installation all affect operating costs. Treat advertised savings as estimates or manufacturer claims, and compare units using consistent test conditions where possible.
Review warranty terms and maintenance needs
Read the warranty for the heat exchanger, parts, and labor separately. Check whether registration, professional installation, or other conditions are required. Also ask the installer what routine maintenance the model needs in your area. Water conditions and the manufacturer’s instructions can affect maintenance requirements, so include those costs in your long-term comparison.
Consider the full installed cost
The purchase price is only one part of the value. Venting, gas-line work, electrical changes, permits, and labor can affect the total cost. Get an installation estimate for the exact model and your home before deciding that a unit is the best deal. A less expensive heater may not be the better value if it requires major upgrades or cannot meet your household’s peak demand.
Frequently Asked Questions
Are tankless gas water heaters suitable for a whole house?
They can be, if the heater is sized for your home’s simultaneous hot-water demand and incoming water temperature. Check the flow rate at the temperature rise your home needs rather than relying only on the maximum GPM in a product title.
Does a higher GPM rating always mean more hot water?
Not in every situation. GPM ratings may use different temperature-rise conditions, and colder incoming water can reduce the flow a heater can raise to your target temperature. Compare ratings under similar conditions whenever possible.
Can I install a gas tankless water heater myself?
Gas, combustion, venting, and electrical work can create safety risks if done incorrectly. Professional installation is recommended, and local codes may require permits or licensed trades. Check the manufacturer’s instructions and local rules before planning an installation.
Should I choose an indoor or outdoor model?
Choose based on your home’s layout, climate, available installation locations, and the model’s venting requirements. Indoor units need approved venting, while outdoor units need an appropriate exterior location. Confirm the exact model configuration before buying.
Will a tankless heater reduce my energy bill?
It may use less energy than a storage tank in some homes because it heats water on demand, but savings vary. Household usage, utility rates, climate, installation, and the efficiency of your current heater all matter. Manufacturer savings claims are not a guarantee of your results.
What does UEF mean?
UEF stands for Uniform Energy Factor, a measure used to compare water-heater efficiency. A higher figure can indicate greater efficiency under the test conditions, but it does not predict your exact monthly bill.
Which model is the best choice for a smaller home?
The ThermoMate CZ422NG has the lowest listed maximum flow rate in this group, while remaining a whole-house indoor model. It may be suitable for moderate demand, but have an installer check the expected simultaneous use and temperature rise before choosing it.
Final Recommendation
For households that need higher listed capacity, the Rheem RTG Series stands out on paper, although its supplied listing is marked unavailable. The Rinnai V53DeN is a clear option if you specifically want an outdoor model, while the ThermoMate is worth comparing for a compact indoor installation. The GASLAND offers a middle ground in listed capacity. Before buying any of them, verify the exact model, sizing, venting, warranty, and total installed cost with a qualified professional.
