Shopping for a tankless water heater can feel like a guessing game. The price tag on the unit looks reasonable, and then the installation quote comes in much higher. That gap is normal, and it helps to know where the money goes before you commit.
In this guide, ARS®/Rescue Rooter® walks you through what a tankless water heater typically costs installed, what pushes the price up or down, and how to decide whether to repair or replace the unit you have. If you're ready to talk with a pro, explore our tankless water heater services, or call your local ARS location for an upfront estimate.
How Much Does a Tankless Water Heater Cost?
ARS reports that tankless water heater installations typically run between about $4,400 and $6,500, depending on unit type and installation complexity. By comparison, a standard tank water heater replacement typically ranges from about $2,300 to $3,500, according to ARS.
These ranges come from ARS national service data on completed residential jobs from January 2025 through January 2026. They reflect real installs, so they may run higher than online averages that only count the unit or a simple swap. Your price will vary by market, equipment, your home, and any discounts in effect.
A tankless water heater (also called an on-demand water heater) heats water only when you turn on a hot water tap. There's no storage tank holding heated water around the clock. That design is why it costs more up front and why it may help lower energy use over time.
What's Included in the Installed Price
The installed price covers much more than the box on the wall. A typical tankless water heater cost and installation quote includes:
- The unit: The tankless water heater itself, sized for your home.
- Labor: Mounting, plumbing connections, and testing.
- Old tank removal: Draining, disconnecting, and hauling away your current water heater.
- Venting or electrical work: New venting for gas units or new circuits for electric units.
- Permits and code compliance: Many areas require a permit and inspection.
ARS provides an upfront written estimate before work begins, so you can see each of these items before you say yes.
What Affects Tankless Water Heater Installation Cost
No two homes are set up the same way, so no two quotes look identical. The table below shows the main factors behind tankless water heater installation cost and which way each one tends to push your price.
| Factor | Why It Matters | Effect on Price |
|---|---|---|
| Fuel type | Natural gas, propane, and electric units have different equipment and hookup needs. | Gas and propane units often cost more to install; electric units may need electrical work. |
| Unit size (flow rate) | Flow rate, measured in gallons per minute (GPM), is how much hot water the unit can deliver at once. | Higher GPM units for larger homes cost more. |
| Efficiency tier | Condensing units capture extra heat from exhaust gases. | Higher-efficiency units cost more up front. |
| Gas line size | Tankless units need a big burst of gas when they fire. | An undersized line may need an upgrade, raising the price. |
| Venting | Gas units need dedicated venting through a wall or roof. | New or rerouted venting adds cost. |
| Electrical capacity | Whole-home electric units draw a lot of power. | New circuits or an electrical panel upgrade adds cost. |
| Location and access | Tight closets, attics, or crawl spaces take more labor. | Hard-to-reach spaces raise labor costs. |
| Water quality | Hard water leaves mineral scale inside the unit. | Scale protection or a softener adds cost. |
| Permits and local code | Requirements vary by city and county. | Permit fees and inspections add cost. |
| Local labor market | Rates differ from region to region. | Higher-cost areas typically see higher quotes. |
Efficiency tier is worth a closer look. According to how ENERGY STAR tankless units work, "An ENERGY STAR certified gas tankless water heater uses a secondary heat exchanger to use 9 percent less energy than a conventional gas tankless water heater." That extra hardware is part of why those models cost more.
Two quotes for the same home can also come in far apart. According to ARS, that's typically not because one contractor is overcharging. Equipment tier, efficiency rating, install complexity, and whether extra work like electrical upgrades is included are the main drivers.
Gas Lines and Venting
If you plan to replace your water heater with tankless, gas line and venting work is often the biggest add-on. A tank water heater uses a steady, small amount of gas. A tankless unit needs much more gas for short bursts, so your existing line may be too small.
Gas tankless units also need their own venting to carry exhaust safely outside. Since ARS also handles gas line installation and repair, you won't need a separate contractor for this part of the job.
Electrical Capacity for Electric Units
Electric tankless units skip the gas line and venting, but they bring their own tankless water heater install cost. Whole-home electric models draw a large amount of power when they run. Many homes need new dedicated circuits, and some need an electrical panel upgrade.
Before you choose electric, have a professional check your panel. ARS offers electrical panel upgrades along with plumbing, so one team can handle the full project.
Water Quality and Scale Protection
Hard water is water with a high mineral content, such as calcium and magnesium. Over time, those minerals leave scale inside the unit's heat exchanger, which can reduce performance and lead to repairs. This can add to your overall tankless hot water heater cost.
If your home has hard water, your installer may suggest a scale-reducing filter or water softener installation. It's an extra cost up front, but it may help protect your new unit.
Tankless vs. Tank Water Heater Cost
The biggest difference between tank and tankless is when you pay. Tank water heaters cost less to install, while tankless units cost more up front but may help lower energy costs over time. Here's how they compare side by side.
| Tankless Water Heater | Standard Tank Water Heater | |
|---|---|---|
| Typical installed cost (ARS data) | About $4,400 to $6,500 | About $2,300 to $3,500 |
| How it heats | Heats water on demand | Keeps a tank of water hot all day |
| Hot water supply | Continuous, within the unit's flow rate | Limited to the tank's size |
| Space needed | Small, wall-mounted | Floor space for a full tank |
| Typical maintenance | Regular flushing to remove scale | Regular flushing to remove sediment |
For a closer look at tank pricing, see our guide to standard water heater costs.
How much you save depends on how much hot water your household uses. Older DOE Building America research found: "Although tankless gas water heaters should save approximately 33% on hot water heating compared to a conventional storage water heater, actual energy savings vary significantly based on individual draw volume."
For gas models, an ENERGY STAR technical bulletin states that "ENERGY STAR certified demand water heaters can save a family of four an additional $95 per year on gas bills." Your results may differ based on your energy rates and habits.
Should You Repair or Replace Your Tankless Water Heater?
If you already have a tankless unit that's acting up, the cost to replace a tankless water heater isn't your only option. Many problems can be fixed. The table below can help you decide which path makes more sense.
| Repair Makes Sense When… | Replacement Makes Sense When… |
|---|---|
| The unit is relatively young and has been reliable. | The unit is near or past the typical replacement window. |
| The problem is a single part, such as a sensor or igniter. | Breakdowns are happening more often. |
| A flush or descaling may restore performance. | The heat exchanger is leaking or badly scaled. |
| The repair quote is a small share of the price of a new unit. | The repair quote is more than half the cost of a new unit. |
| The unit still meets your household's hot water needs. | Your household has outgrown the unit's flow rate. |
ARS uses a simple rule of thumb for home systems: if a repair quote is more than half the cost of a new system and the unit is over 10 years old, replacement usually makes more financial sense over the life of the system. As a general guideline, ARS recommends planning for water heater replacement every seven to eight years. That timeline can vary with usage, water quality, maintenance history, and installation quality.
Before you decide, check our list of common tankless water heater problems to see if your issue is a quick fix. For a deeper look at the decision, read our repair or replace guide.
Ways to Manage Tankless Water Heater Cost
You may have seen older articles promising a 30% federal tax credit for water heaters. That credit has ended. According to IRS guidance on the credit, "The credit will not be allowed for any property placed in service after December 31, 2025." Talk with a tax professional if you have questions about your situation.
There are still ways to lower the cost of tankless water heater installation:
- Check state rebates: The DOE Home Energy Rebates program notes that "Home Energy Rebates are now available in select states." Check with your state energy office to see what qualifies.
- Ask your utility: Some gas and electric utilities offer rebates on high-efficiency water heaters.
- Right-size the unit: A unit sized to your real hot water use avoids paying for capacity you don't need.
- Get an itemized estimate: Ask for a written estimate that lists gas line, venting, and electrical work separately.
- Consider financing: Spreading out payments can make the upgrade easier on your budget. Learn about ARS financing options.
- Plan ahead: Replacing before your old water heater fails gives you time to compare options instead of making a rushed decision.
Is a Tankless Water Heater Worth the Cost?
For many homeowners, yes. A tankless water heater is usually a strong fit if your family runs out of hot water, you plan to stay in your home for years, you want to free up floor space, or your home already has adequate gas or electrical service.
It may not be the best choice if you're on a tight budget or your home needs major gas line or electrical panel work. In that case, a high-efficiency tank may give you better value. Not sure which way to go? Learn more about whether tankless fits your home.
Whichever you choose, we don't recommend a DIY install. Gas lines, venting, and high-power electrical work carry real safety risks, and improper installation may void the manufacturer's warranty.
When to Call a Professional
Some signs mean it's time for an expert to take a look:
- Error codes on the unit's display
- Water that turns lukewarm or swings between hot and cold
- Leaks or moisture around the unit
- Unusual noises, such as rumbling or clicking
- A gas smell near the unit (leave the house and call your gas company right away)
Our trusted, experienced team provides upfront written estimates and backs our work with the Exceptional Service Guarantee. Call your local ARS location or Schedule Service Online. We're available seven days a week.
