Tankless Water Heater Cost: Gas, Electric & Solar

Building or renovating a home means weighing dozens of choices, and the water heater is an easy one to overlook. Sticking with a traditional tank is the cheap upfront option, but it can cost you more over the years you own the house.

A tankless water heater flips that math. It heats water on demand, so you get a near-endless supply and skip the standby energy loss of keeping a full tank hot around the clock. The catch is the higher price to buy and install one.

This guide breaks down what a tankless water heater actually costs, how gas, electric, and solar options compare, and where the money goes during installation.

How Much Does Installation Cost?

Most homeowners pay somewhere between $1,200 and $3,800 to have a tankless water heater installed, and the typical all-in bill lands near $2,600 ⁽¹⁾. That is well above a standard tank water heater, which usually costs between $761 and $1,426 to install ⁽²⁾.

The range is wide because the unit is only part of the bill, and fuel type drives most of the gap. A gas tankless heater tends to run about $2,400 to $4,800 installed, while an electric one lands closer to $1,900 to $3,600. Electric models cost roughly 30 to 40 percent less to put in because they need no venting or gas line.

Here is how national average costs compare by heater type:

Additional Cost Factors

The sticker price on the unit isn’t the only expense. Labor, permits, and home modifications play a huge role in the final bill.

• Unit Quantity: Large homes with spread-out bathrooms may need more than one tankless unit to prevent lag time.
• Fuel Source: Your choice of fuel impacts long-term savings. Water heaters are a major drain on energy bills, so choose wisely.
• Maintenance: While tankless units require less maintenance than tanks, you still need to budget for annual flushing to remove scale buildup.
• Reconfiguration: If you are switching from a tank to tankless, you may need to move piping or upgrade gas lines, which increases labor costs.
• Disposal: Removing your old system costs money. Some installers include this in the quote, but always ask to be sure.

Types of Tankless Water Heaters

Tankless water heaters are often called on-demand or instantaneous heaters ⁽³⁾. Instead of heating a massive tank 24/7, these units flash-heat water only when you turn on the tap.

Most homes use gas or electric models. Neither is inherently “better,” but your home’s existing utility setup usually dictates the right choice. It is worth consulting a professional to see if your gas line or electrical panel can handle the load.

Gas Tankless Water Heaters

Gas units run on natural gas or propane. Natural gas requires a permanent line hookup, while propane requires regular tank delivery. Gas heaters are powerful, with outputs ranging from 140,000 to 380,000 BTUs.

These units are generally more expensive to buy and install. Expect to pay at least $1,000 for the unit alone.

Venting Requirements
Venting is the trickiest part of gas installation. Non-condensing units need Category III stainless steel venting to handle the exhaust. This material is expensive.

Condensing tankless systems are more efficient and often easier to vent. While non-condensing units run at 80% efficiency, condensing units exceed 90%.

Although gas costs more upfront, it is usually cheaper to operate monthly. If gas is affordable in your area, this is the smart long-term play. Plus, gas units often work during power outages (if they have battery backup ignition), whereas electric units will fail.

Electric Tankless Water Heaters

If you want to save cash upfront, go electric. These units average around $500 and are much easier to install since they don’t require venting.

Electric heaters produce zero greenhouse gases and are compact enough to fit in a closet or under a sink.

The Electrical Panel Issue
The biggest hurdle is power. An electric tankless heater pulls a massive amount of electricity, often 120 amps or more. If your home has an older 100-amp or 150-amp panel, you will need a service upgrade. Upgrading your electrical panel can add $1,500 or more to the project.

However, electric units are simple to troubleshoot and maintain. This simplicity helps them easily reach their 20-year lifespan ⁽⁴⁾.

Solar Water Heaters

Solar is the most efficient option of the three. A solar water heating system can cut your water heating bills by 50% to 80% ⁽⁵⁾, and because it runs on sunlight, you are not exposed to swings in gas or electricity prices.

One thing has changed on the incentive side. The federal Residential Clean Energy Credit that used to cover solar water heaters no longer applies to systems placed in service after the end of 2025 ⁽⁶⁾, so check for current state, local, or utility rebates before you budget around a federal write-off.

There are two main types of solar configurations:

1. Passive Systems

These are cheaper and generally more reliable but aren’t great for freezing climates.

• Integral Collector Storage (ICS): Cold water flows into a collector on your roof, heats up, and flows to your plumbing.
• Thermosiphon: Ideal for strong roofs, this system uses natural physics (warm water rises) to move water from a collector into a heavy storage tank mounted on the roof.

2. Active Systems

These use pumps to circulate water and are better for colder regions.

• Direct (Open-Loop): Pumps circulate household water through the collectors. Best for climates that don’t freeze.
• Indirect (Closed-Loop): Pumps circulate a freeze-proof antifreeze solution through the collectors and a heat exchanger. This heats the water without exposing pipes to freezing air.

Choosing the Best Unit for Your Home

Picking the right heater depends on your climate and your family’s habits.

If you live in a cold climate, the groundwater is colder. The heater has to work harder to warm that water up. Gas heaters are generally better for these environments because they can raise temperatures faster than electric models.

You also need to calculate your water usage. If you run the dishwasher, washing machine, and shower at the same time, you need a high GPM (Gallons Per Minute) rating.

Single-Point Systems

Also known as “point-of-use” units, these are small heaters installed right near a faucet or shower ⁽⁷⁾.

These are perfect for a guest bathroom, an outdoor kitchen, or a home addition where running new pipes is too expensive. However, you cannot run an entire family home on one single-point system.

Whole-Home Units

These powerful units replace your main boiler and supply every tap in the house. They are larger and more expensive but necessary for standard living.

You need to measure your utility space before buying. While smaller than tanks, they still need clearance for venting (if gas) and maintenance.

Here is a look at the top brands and their average costs:

DIY or Hire a Professional?

Installing a tankless water heater is not a beginner DIY project. Most cities require a permit and a safety inspection.

Gas lines, venting, and high-voltage electricity are dangerous if mishandled. Hiring a pro ensures your family is safe and your home stays up to code.

FAQs

What Is the Downside of a Tankless Water Heater?

The main downsides of a tankless water heater are its higher upfront cost and the brief “cold water sandwich” effect. Because it stores no hot water, turning the tap off and quickly back on can push a short slug of cold water through the line. Very cold groundwater can also stretch the unit when you run a shower and the dishwasher at the same time.

Why Is Tankless Water Heater Installation so Expensive?

Tankless water heater installation is expensive because it usually means retrofitting your home, not just swapping a box. A gas unit may need a new gas line and stainless steel venting, and a whole-home electric unit can require a heavy-duty panel upgrade. Replacing one tankless unit with another skips most of that work and costs far less.

Can a Tankless Water Heater Fill a Bathtub?

Yes, a tankless water heater can fill a bathtub, and it will not run out of hot water partway through. What varies is the fill time, which depends on the unit’s flow rate in gallons per minute (GPM). Pair a large soaking tub with a low-GPM heater and the tub simply takes longer to fill.

Is a Tankless Water Heater Worth the Cost?

A tankless water heater is usually worth the cost for homes that use about 41 gallons of hot water or less per day. At that level of use, tankless units run 24% to 34% more energy-efficient than storage-tank heaters, and that efficiency plus a 20-year-plus lifespan recovers part of the higher price over time.

How Long Do Tankless Water Heaters Last?

Tankless water heaters typically last 20 years or more, close to double the 10-to-12-year life of a traditional tank heater. Reaching that mark comes down to maintenance: descaling the unit once a year keeps mineral buildup from cutting its life short, especially in hard-water homes.

What Size Tankless Water Heater Do I Need for a Family of 4?

A family of four generally needs a tankless water heater rated for about 7 to 10 gallons per minute (GPM). That capacity covers two showers at once, or a shower plus the dishwasher, without the temperature dropping. Colder incoming groundwater pushes you toward the higher end of that range.

Do You Need a Tankless Water Heater for Each Bathroom?

No, you do not need a separate tankless water heater for each bathroom. Most homes run a single whole-home unit that supplies every bathroom and appliance. The exception is a bathroom far from the main unit, where a small point-of-use electric heater can add instant hot water and cut the wait.

Can You Run Out of Hot Water With a Tankless Water Heater?

You cannot empty a tankless water heater the way you drain a tank, because it heats water on demand. You can, though, overwhelm it. Ask for more hot water than the unit can heat at once, say three showers running together, and the temperature drops or the flow slows until demand eases.

What Maintenance Is Needed on a Tankless Water Heater?

The key maintenance task for a tankless water heater is flushing it once a year to clear mineral scale, or more often on hard water. Skip it and scale buildup can eventually cause a failure. Adding a water softener slows the buildup and stretches the time between flushes.

Does a Tankless Water Heater Increase Home Value?

A tankless water heater can raise your home’s appeal to buyers as a modern, energy-efficient upgrade. It may not add a large fixed sum to the appraisal, but it signals an updated, well-maintained house and can help a sale. Buyers also value the endless hot water and the closet or floor space a tankless unit frees up.

Final Thoughts

A tankless water heater lowers your energy use and your monthly bills at once, running with far better efficiency than an old-school tank.

The trade-off is the price to get in. A professionally installed unit usually runs about $1,200 to $3,800, and the exact figure depends on fuel type and how much gas, venting, or electrical work your home needs. Weigh your daily hot-water use against that budget, and if you switch, hire a licensed pro so your warranty stays valid and your showers stay hot.