The best gas hot water heater for many homes is a tankless model that supplies endless hot water and takes up very little space. A tankless gas hot water heater heats water only when you open a tap, so you avoid the standby heat loss of a traditional tank.
Our top pick is the Rheem RTG-70DVLN-3 Natural Gas Tankless Water Heater. It delivers up to 7.0 gallons per minute (GPM), which supports two to three simultaneous showers, and it carries a 0.82 UEF efficiency rating in a compact wall-mount design.
Best Gas Hot Water Heater: Top Picks Compared
Our top pick for gas hot water heaters is the Rheem RTG-70DVLN-3 7.0 GPM Natural Gas Tankless.
Pros
- Delivers continuous hot water supply for multiple simultaneous uses without depletion
- Highly energy efficient with 0.82 UEF rating and minimal monthly gas consumption
- Compact footprint and wall-mount installation saves significant floor space
- Hot Start Programming keeps unit ready-state, eliminating annoying cold water delays
- Comprehensive safety features including freeze protection and flame failure detection
Cons
- Initial water temperature can take time to reach desired heat at the tap
- Requires professional installation for proper venting and gas line connections
- Needs periodic maintenance with vinegar flushing in hard water areas to prevent scaling
The Rheem RTG-70DVLN-3 is a high-performance natural gas tankless water heater designed for large families and multi-bathroom homes that demand continuous hot water without the bulk of traditional tank systems. This unit delivers 7.0 GPM flow rate at a 35 degree Fahrenheit temperature rise, supporting 2-3 simultaneous showers or water points with its 160,000 BTU output. It's an excellent replacement for aging tank water heaters, particularly for households tired of running out of hot water during peak usage times.
What sets this Rheem unit apart is its combination of efficiency and user-focused engineering. The exclusive Hot Start Programming keeps the heater in a ready state, virtually eliminating cold water bursts that plague some tankless systems between uses. The 0.82 Uniform Energy Factor means you'll see real savings on your gas bills, with users reporting increases of only $2-3 monthly compared to previous electric heaters. The integrated digital LED display offers precise temperature control with plus or minus 1 degree adjustments, giving you consistent water temperature exactly as you prefer it.
Build quality is solid throughout, with a stainless steel construction and wall-mount design that occupies minimal space compared to bulky tank heaters. The compact 13.5-inch width and 24.2-inch height fit into tight spaces while maintaining industry-leading installation clearance. The Overheat Film Wrap provides heat exchanger protection, and LeakGuard Leak Detection monitors for internal leaks both large and small, offering valuable peace of mind against potential water damage. The unit operates at just 132 watts and includes universal venting compatibility plus half-inch gas line compatibility for flexible installation options.
One honest drawback is that some users report a slight delay in reaching desired water temperature at the tap, particularly for the first use after a period of inactivity. This is inherent to how tankless systems work and can be partially mitigated by the Hot Start feature. In hard water areas, the unit requires biannual vinegar flushing to maintain optimal performance and prevent mineral scaling, adding a small maintenance requirement that tank heaters don't demand.
The Rheem RTG-70DVLN-3 is backed by an impressive warranty including 15 years on the heat exchanger and 5 years on parts, reflecting the manufacturer's confidence in durability. For households ready to eliminate hot water shortages and reduce energy consumption, this tankless system delivers reliable performance and genuine long-term value. It's particularly well-suited for families with multiple bathrooms or high simultaneous water demand.
Performance Metrics: Flow Rate: 7.0 GPM at 35 degree Fahrenheit temperature rise. Heat Output: 160,000 BTU/hr. Maximum Temperature: 140 degrees Fahrenheit. Energy Factor: 0.82 UEF (saves up to 34% vs. 50-gallon electric tanks).
Physical Specifications: Dimensions: 13.5 inches width by 24.2 inches height by 10.27 inches depth. Weight: 46.5 pounds. Mount Type: Wall. Material: Stainless Steel. Color: Gray.
Electrical and Fuel: Power Source: Natural Gas. Wattage: 132 watts. Voltage: 120 volts. Gas Line Compatibility: 1/2 inch. Venting: Universal compatibility with direct vent system.
Features: Integrated Digital LED Display. Hot Start Programming. High Energy Efficiency. Integrated Leak Detection and Prevention. Freeze Protection. Flame Failure Protection. Temperature Control: Plus or minus 1 degree precision adjustment.
Warranty: 1 Year Labor. 15 Years Heat Exchanger. 5 Years Parts.
Who Should Buy This Unit: The Rheem RTG-70DVLN-3 is ideal for families of 3 or more living in homes with multiple bathrooms or high simultaneous water demand. It's perfect for households currently using electric tank heaters who want to reduce energy consumption and eliminate hot water shortages. The compact design makes it suitable for apartments, condos, and homes with limited utility space.
Installation Considerations: This is not a DIY-friendly product for most homeowners. Professional installation is strongly recommended to ensure proper gas line connections, venting configuration, and local code compliance. Budget for professional installation costs in addition to the unit price. Confirm your home has natural gas service and adequate venting options before purchasing.
Maintenance Requirements: In areas with hard water, plan to flush the unit with distilled white vinegar twice yearly to prevent mineral buildup and maintain efficiency. This is a simple process but requires commitment. Soft water areas may need flushing less frequently. Regular inspection of the LeakGuard system is recommended as part of routine home maintenance.
Comparison Context: Compared to traditional tank heaters, this unit costs more upfront but delivers lower operating costs, unlimited hot water supply, and space savings. Compared to other tankless systems, Rheem's reputation for reliability and the Hot Start feature that eliminates cold water delays make this a strong value choice. The 15-year heat exchanger warranty is longer than many competitors offer.
Our Best Gas Hot Water Heater Picks Reviewed
Among the gas hot water heaters we reviewed, the Rheem RTG-70DVLN-3 7.0 GPM Natural Gas Tankless stands out, and every pick is judged on performance, features, and value.
- 7.0 GPM flow: enough hot water for two to three showers at once.
- 0.82 UEF: efficient performance that helps reduce energy use.
- Compact wall mount: frees up floor space compared with a tank.
- Endless hot water: no waiting for a tank to recover.
- Trusted brand: Rheem is a well-established water heater manufacturer.
How to Choose the Best Gas Hot Water Heater
Choosing the right gas hot water heater comes down to tank or tankless, flow rate (GPM), efficiency (UEF), and venting.
- Tank or Tankless: A tank heater stores hot water and is usually cheaper to buy. A tankless gas hot water heater costs more up front but provides continuous hot water and saves space.
- Flow Rate (GPM): Add up the fixtures you use at the same time. A typical shower uses about 2 GPM, so a 7.0 GPM unit can supply several showers at once in many climates.
- Efficiency (UEF): The Uniform Energy Factor (UEF) measures efficiency. Higher numbers mean lower operating costs.
- Venting: Tankless gas units need proper venting. The “DV” in the Rheem model name refers to direct venting.
- Gas Type and Supply: Make sure the unit matches your fuel (natural gas or propane) and that your gas line can supply enough BTUs.
Installation Considerations
- Tankless gas units often need a larger gas line than tank heaters.
- Venting must follow local codes and manufacturer instructions.
- A licensed plumber or gas technician should install the unit.
- Consider a water softener or regular descaling in hard water areas.
Maintenance Tips
- Flush the heat exchanger once a year to remove scale.
- Clean the inlet water filter regularly.
- Check vents for blockages.
- Schedule professional service as recommended.
For more options, read our guides to the best gas hot water heaters and the best tankless hot water picks.
Sizing for Your Household
The Rheem RTG-70DVLN-3 is rated up to 7.0 gallons per minute under favorable conditions. In practice, flow depends on the temperature rise you need. Add up the fixtures you use at the same time, such as showers at about 1.5 to 2.5 gallons per minute each, and compare that with the heater’s flow at your local incoming water temperature.
Direct-Vent Design
Direct-vent models draw combustion air from outside and vent exhaust outdoors, which can make installation more flexible in tight spaces.
Permits and Professional Installation
Gas water heaters need a correctly sized gas line, approved venting, and often a permit and inspection. A licensed plumber or gas fitter should handle installation. Install a carbon monoxide detector near any gas appliance.
Common Mistakes to Avoid
Do not reuse old venting without confirming it is approved. Avoid undersized gas lines, and plan for annual descaling when choosing a gas hot water heater.
Final Verdict on the Best Gas Hot Water Heater
For whole-house use, the Rheem RTG-70DVLN-3 is an excellent gas hot water heater, delivering 7.0 GPM of continuous hot water with a 0.82 UEF rating. It is a smart choice for households that want endless hot water and more floor space.
Gas Hot Water Heater FAQs
Common questions from buyers include “Is a tankless gas water heater worth it?”, “How many showers can a 7.0 GPM unit handle?”, and “Do tankless gas heaters need special venting?”.
Is a tankless gas water heater worth it?
Yes, for households that want endless hot water and lower standby losses.
How many showers can a 7.0 GPM unit handle?
Usually two to three at once, depending on climate and fixtures.
Do tankless gas heaters need special venting?
Yes. They require proper venting according to code.
Can I install it myself?
Hire a licensed professional for gas and venting connections.
How long do tankless gas heaters last?
Many last 15 to 20 years with regular maintenance.
For more home gear, browse our best water heaters category.
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