Are tankless water heaters gas or electric? The answer is both: tankless water heaters are available in gas-fired and electric models. This guide explains the key differences to help you choose the right type for your home.
Understanding Tankless Water Heater Types
Tankless water heaters, also known as on-demand water heaters, heat water only when you need it. They come in two primary fuel types: natural gas (or propane) and electricity. Each has distinct advantages and limitations.
Gas Tankless Water Heaters
Gas tankless units use a burner to heat a heat exchanger, providing a high flow rate (typically 5–10 gallons per minute). They require proper venting to the outdoors and a gas line connection. According to the U.S. Department of Energy’s Energy Saver guide on water heating, gas tankless models often achieve higher energy factors than electric models, especially in colder climates where electric units struggle to maintain temperature. However, installation costs are higher due to venting and gas piping requirements. If your home already has natural gas service, a gas tankless heater can be a great option.
Electric Tankless Water Heaters
Electric tankless units use heating elements to warm water. They are generally smaller, require no venting, and have lower upfront costs. The EPA WaterSense program notes that electric tankless heaters can be highly efficient, but their flow rate is limited—usually 2–5 gallons per minute—making them better suited for point-of-use applications or homes with moderate hot water demand. They also require a significant electrical panel upgrade (often 100+ amps) to handle the load. In regions with high electricity rates, operating costs may be higher than gas.
Key Differences Between Gas and Electric Tankless Water Heaters
Below is a comparison of the most important factors to consider when deciding between gas and electric tankless water heaters.
| Feature | Gas Tankless | Electric Tankless |
|---|---|---|
| Fuel Source | Natural gas or propane | Electricity |
| Energy Efficiency (UEF) | 0.82–0.96 (higher in warm climates) | 0.94–0.99 (no standby loss) |
| Flow Rate (GPM) | 5–10 GPM (whole-house capable) | 2–5 GPM (best for 1–2 fixtures) |
| Installation Cost (US typical range) | $1,000–$3,000 (varies by region) | $500–$1,500 (varies by region) |
| Operating Cost | Lower in most regions (gas cheaper per BTU) | Higher if electricity rates are high |
| Lifespan | 15–20 years (with annual maintenance) | 15–20 years (with annual maintenance) |
| Venting Required | Yes (stainless steel or PVC) | No |
| Space Needed | Larger unit + clearance for venting | Compact, wall-mountable |
Which One Is Right for Your Home?
To decide, evaluate these factors:
- Fuel availability: Does your home have natural gas or propane? If not, electric may be the only option unless you install a new gas line.
- Climate: In cold regions, gas units maintain higher flow rates because incoming water is colder. Electric units lose efficiency when water temperature drops significantly.
- Electrical panel capacity: Electric tankless heaters often require 100–150 amps of dedicated service. An older panel may need an expensive upgrade.
- Hot water usage: For households with simultaneous showers, laundry, and dishwashing, a gas unit’s higher flow rate is beneficial. For a single bathroom or point-of-use, electric works well.
- Installation and maintenance: Gas units need annual inspection of burners and venting. Electric units have fewer parts but may require descaling in hard water areas. Regular water heater repair and flushing can extend lifespan.
- Rebates and incentives: Check local utility or state programs; some offer incentives for high-efficiency gas or electric models.
If you’re still unsure, consult a professional plumber. They can assess your home’s gas line, electrical system, and hot water needs. For existing plumbing issues like leak detection or pipe repair, our team can help before or after installation.
Frequently Asked Questions
Are tankless water heaters gas or electric?
Both types exist. Gas models use natural gas or propane and offer higher flow rates. Electric models are simpler to install but have lower flow rates and may require a heavy electrical circuit.
Which is more efficient: gas or electric tankless?
Electric models have higher uniform energy factor (UEF) ratings (0.94–0.99) because they have no standby losses. However, gas models can be more cost-effective to operate if natural gas prices are low. The overall efficiency also depends on your climate and usage patterns.
Can I replace my old tank water heater with a tankless?
Yes, but you may need to upgrade your gas line or electrical panel. A licensed plumber can evaluate your current setup and recommend the best tankless option. For help with toilet repair or other plumbing upgrades, we can assist.
Do tankless water heaters work during a power outage?
Electric tankless units will not work without power. Gas tankless units require electricity for the control board and ignition, so they also stop working during a blackout unless you have a backup generator. Consider a battery backup or a hybrid solution if outages are common.
How long do tankless water heaters last?
With proper maintenance—annual flushing and inspection—both gas and electric tankless units can last 15–20 years. Hard water may require more frequent descaling. For homes with hard water, a water softener can protect the heat exchanger.
Do I need a permit to install a tankless water heater?
Most local codes require a permit for gas and electric tankless installations. The International Association of Plumbing and Mechanical Officials (IAPMO) provides guidelines to ensure safety and compliance. Always hire a licensed plumber who pulls the necessary permits.
Ready to upgrade your water heating system? Our team at MyTownPlumber can help you choose and install the right tankless water heater for your home. Contact us today for a free estimate and take advantage of our current plumbing offer.
— MyTownPlumber Editorial Team