Gas Tankless Water Heater Cost | Gas Water Heater System Price Guide

Our gas tankless water heater buying guide covers all the details needed to make an informed decision about the best choice for your home. Unit cost, installation labor charges, water heater sizes and output, best brands are more are discussed in the most comprehensive guide of its kind.

We’ve included the new class of gas tankless water heaters that are designed for point of use applications or, at most, two points of use simultaneously.

Gas Tankless Water Heater Closeup

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Average Costs for Gas Tankless Water Heater Installation and Replacement

The average cost of a gas tankless water heater including home installation is $1,150 to $3,650. That’s a wide range, but for a whole-house heater that can serve at least 3 locations at once – a sink, the dishwasher and a shower, for example – expect to pay between $2,600 and $3,400 based on the unit, its quality, features and where it is installed. The lower end of this price range primarily includes smaller models with a low flow rate, while the more expensive end of the price range is for whole-house tankless water heaters with high GPM.

What’s GPM? Likely you know, but as a reminder, it is gallons per minute of hot water the unit can deliver at peak performance.

Buying tip: You’ll get about half to three-quarters of the rated GPM unless you live in a warm climate. That’s because the ratings are based on incoming water that is 65F to 75F, which is warmer than the water coming into homes where winters are cold.

For example, the Navien NPE-2 180,000 BTU unit is rated for 8.4 GPM if the temperature rise is just 35 degrees – meaning it enters the house at about 85 degrees! But if the water has to be heated 70 degrees (entering the house at 50F), common in cold regions, then GPM falls to 4.2 – exactly half.

Because rated GPM can be misleading, many manufacturers are moving away from giving a rating. Instead, they offer a chart showing Temperature Rise in one column (35, 40, 45…usually up to about 100) and GPM in another. The higher the necessary rise to get to 120F, the lower the GPM.

Let’s get into a breakdown of gas tankless water heater costs, popular brands and prices and more.

Average Cost of a Tankless Gas Water Heater, Supply Only

How much is a gas tankless water heater? This section covers unit costs – not installation, which is detailed in the next section.

About 95% of gas tankless water heaters are used for entire homes (whole house) rather than point of use. However, brands like Marey have introduced smaller units designed for one point of use, and they are pretty cheap in cost and quality. We’ve included them in the Gas Tankless Water Heater Cost table below, but keep in mind that there are a limited number of options for units rated for less than 4 GPM.

As a result, gas tankless water heater cost is less than $200 to $3,000 when point of use (POU) and whole house units are included.

Most whole house units cost between $700 and $1,800. You can pay more from some sellers, but if you shop around, there’s no reason to pay above $2,400 for a large-volume tankless gas water heater.

Gas Tankless Water Heater Unit Cost Overview

Gas Tankless Water Heater Cost
Capacity/GPM Unit Cost Average Cost Type
Up to 1.5 $180 – $290 $230 POU/Whole House
1.6 to 3.0 $260 – $450 $350 POU/Whole House
3.1 to 5.0 $330 – $775 $635 Whole House
5.1 to 7.0 $595 – $1,450 $925 Whole House
7.1 to 9.0 $800 – $1,900 $1,285 Whole House
9.1 to 11+ $950 – $2,400 $1,625 Whole House
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Some brands, Rinnai in particular, are very expensive, and account for the high end of the price spectrum. Most brands are in the low to middle of our cost ranges.

Condensing vs non-condensing tankless water heaters: Condensing models are the most efficient because they employ a second heat exchanger to transfer combustion heat into the water. Less heat is lost in the exhaust. Condensing models achieve efficiency ratings above 90% vs in the 80s for non-condensing units with a single heat exchanger. As a result of the second heat exchanger, condensing models cost $150 to $300 more.

Gas Tankless Water Heater Installation Costs

There’s a wide range here because gas units come in indoor and outdoor types.

As you would expect, indoor installation – which is most common – costs about double what outdoor installation costs. Indoor units must be vented out of the home, so there are higher costs for materials and labor.

Here are common installation costs for DIY, replacement and new water heater installation.

  • DIY Outdoors: $0 to $500 for materials depending on whether you are replacing an old unit (low cost) or running new gas line, water line and electrical for a first-time unit.
  • DIY Indoors: $200 to $1,000 for materials depending on whether it is replacement (low cost) or installing a new unit with new gas line, water line, electric and venting.
  • Outdoor Unit Replacement: $200 to $500. Removing an existing water heater and connecting the new unit to wiring and plumbing that is already in place is a quick job, so cost is relatively low.
  • Indoor Replacement: $350 to $700. When wiring, a gas line and vent are in place, installation cost is much lower. Some modification is often needed for the exhaust vent or gas line, but labor and material costs are lower than for installation of a new unit.
  • Indoor New Unit: $1,400 to $2,600. This is the costliest installation type. Once the unit is mounted, electrical wiring, a gas line and incoming and outgoing water lines must be run. And the unit must be vented.
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Gas Tankless Water Heater Costs for Top Brands

The following is a list of the top brands for gas tankless water heaters and their average prices. These prices reflect the cost of the unit only, not including installation.


Navien is considered a premium – and pricey – brand of tankless water heater. Models range from around 5.0 to 9.5 GPM. We’ve completed a Navien Review and Cost Guide with more information.


Rinnai has been a leading brand of tankless gas water heaters for decades. It produces indoor and outdoor, NG and LP models, as most large brands do. Rated capacity ranges from about 5.5 GPM to 11 GPM – but remember, you probably won’t get that much hot water unless you live in a warm climate. We’ve completed a full review of Rinnai tankless water heaters.


This is a well-established brand in Asia and Europe that has begun selling units in North America. Quality is considered above average, and the units are fairly expensive. Sizes are consistent with other leading brands – about 5.5 GPM to around 10 GPM for the largest units.


Bosch is a mid-range brand in terms of quality and affordability. The Therm line is the top seller, but it has a limited range of sizes with water heaters rated for up to 12.1 GPM. Bosch is a huge company with many product lines, and our recommendation is to stick with a brand that specializes in tankless water heaters.


Rheem makes reliable tankless water heaters at competitive prices. Because the brand is so large and owns a big share of the market, you won’t have trouble finding someone to repair the unit – and parts are readily available – if repair is needed. See our Rheem Tankless Water Heater Review for models, costs and more.


This brand only makes tankless water heaters, and its units are rated among the best available. Sizes start at 5.0 GPM. The largest is rated at 13.2 GPM.


Ecosmart is a newer brand – as perhaps the name indicates. Like most major brands, it makes both non-condensing units with efficiency in the 80s and condensing models with 90% or higher energy efficiency. The size range is limited compared with other brands – about 6.4 to 9.5 GPM.

Gas Tankless Water Heater Costs by Brand
Brand Cost
Navien $1,200 – $3,500
Rinnai $700 – $2,600
Takagi $800 – $2,000
Bosch $700 – $2,500
Rheem $650 – $2,500
Noritz $1,200 – $2,500
Ecosmart $600 – $2,000
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Gas Tankless Costs by Installation Location

Installing a gas tankless water heater indoors vs. outdoors can have a significant effect on the cost of installation. This is because an outdoor gas tankless water heater does not require a vent to be installed because it can release exhaust directly outside, while an indoor gas tankless water heater needs a vent that leads to the outdoors where it can release exhaust.

Indoor Gas Tankless Water Heater Costs

$900 – $1,500 for installation, plus the cost of the unit

Outdoor Gas Tankless Water Heater Costs

$600 – $1,000 for installation, plus the cost of the unit

Gas Unit Operating Costs

One of the biggest selling points for tankless water heaters is their energy efficiency. While the initial costs for a gas tankless water heater are similar to a standard water heater, the long-term savings are what really make a difference.

How much does it cost to run a gas tankless water heater?

Cost to Operate Gas Tankless Water Heater for One Year

$175 – $550

Overview of Gas Tankless Operating Costs
Capacity Annual Cost
Up to 1.5 $175 – $350
1.6 to 3.0 $210 – $375
3.1 to 5.0 $250 – $415
5.1 to 7.0 $280 – $450
7.1 to 9.0 $350 – $500
9.1 to 11+ $430 – $550

Tip: Are you trying to lower your utility bill? Try going a little quicker in the shower and running the dishwasher with full loads instead of doing the dishes by hand. These two tricks will save energy and money!

Natural Gas vs. Propane Tankless Water Heater Costs

What’s the difference between propane and natural gas tankless water heaters? In terms of upfront cost for a unit, natural gas tankless water heaters tend to be slightly cheaper than propane units. But the main cost differences between these types of fuels come down to long-term use and fuel efficiency.

Note: You might not have a choice, of course. If natural gas is available where you live, there isn’t a reason to consider propane. And in some rural areas, propane is your only fuel option.

Natural Gas Tankless Water Heaters

Pros: Natural gas is cheaper than propane on its own per BTU (British Thermal Unit). It is also much more convenient to refill your unit with natural gas because it can be piped in through a line leading directly to your home.

Cons: Natural gas also has a slightly lower energy-efficiency than propane.  That’ surprises people, but it is true. But it certainly isn’t worth having a local propane dealer set a tank to fuel a water heater if you are already served by natural gas.

Propane Tankless Water Heaters

Pros: Propane is readily available almost everywhere, and it is much easier to get and store than natural gas. Though more expensive to buy than natural gas, propane has more energy per gallon, so a gallon of propane can heat more water than a gallon of natural gas.

Cons: While prices fluctuate quite a bit, propane is more expensive than natural gas in most regions of the country.

Permits & Installation Schedule

Permit and Inspection Costs

In most cities and counties, permits and inspections are required for new or replacement water heaters. This is because a water heater can be one of the most dangerous appliances in the home, and it is extremely important that the installation is done correctly to avoid injury to your household and home.

Not all areas have the same requirements, so make sure to check your local regulations before you begin the project so that you can get any permits that are required.

A permit needs to be acquired before you install a new or replacement tankless water heater, and an inspection is done after the installation is completed.

Permit Average Cost

$100 – $500

Inspection Average Cost

$180 – $250

These are totals. For a new (not replacement) gas water heater, you need electrical, mechanical and plumbing permits and inspections!

Timeframe and Installation Schedule

How long does it take to install a gas tankless water heater?

Usually between 4 and 8 hours. If there are no complications and no vent required, a professional installation could take as little as 4 hours or less. If the installation requires extra work such as making a vent, the project will probably take a full day or more for a professional contractor to finish.

  • Replacement point of use installation using existing utilities (gas, water, electric, vent): 2-5 hours
  • New point of use installation with new utilities: 6-10 hours
  • Replacement whole house installation using existing utilities: 3-6 hours
  • New whole house installation with new utilities: 6-12 hours

The Best Gas Tankless Water Heaters

We’ve compiled a list of the top five gas tankless water heaters on the market today! In no particular order, here are the five best units available right now:

Unit Name Brand Location/Fuel Flow Rate Price
RUC98iN Ultra Series Rinnai
  • Indoor/
  • Natural Gas
9.8 GPM $1,850
NRC661-DV Noritz Indoor/Natural Gas or Propane 6.6 GPM $1,000
V94iN High Efficiency Rinnai
  • Indoor/
  • Natural Gas
9.8 GPM $1,050
RTGH-95DVLN Direct Vent Rheem
  • Indoor/
  • Natural Gas
7.4 GPM – 9.5 GPM $1,200
V53DeP Rinnai
  • Outdoor/
  • Propane
5.3 GPM $650

Factors Affecting the Gas Tankless Water Heater Cost

The total cost of a gas tankless water heater is the cost of the unit plus the cost of installation. In the following section, we break down the pieces that will determine the cost of the tankless water heater unit itself, and the things that affect the cost of installation.

Factors Affecting the Cost of the Gas Tankless Water Heater Unit

There are several qualities to consider when choosing a gas tankless water heater that will affect the cost. We’ve listed the main cost factors below.

  • Flow Rate – In general, the higher a unit’s flow rate, the more expensive that unit will be. A higher flow rate means that a tankless water heater can produce more gallons of hot water per minute. You want to find the sweet spot of enough GPM to fulfill your hot water needs while not overpaying for GPM you don’t need or use. In general, a family of two to four people can use a tankless water heater with 5 – 10 GPM, and a family of five or more people will need a unit with 10+ GPM. Remember, you’re likely to get about half the rated GPM, especially in winter.
  • Natural Gas vs. Propane – Tankless water heaters that use natural gas are almost always less expensive than units of the same size that use propane. You’ll see a cost difference of $35 to $75.
  • Quality – As with most appliances, gas tankless water heaters are available in budget-friendly units, premium units, and everything in between. Before deciding on a unit, make sure to assess your home’s needs. Do you need to find a cheap unit right away? Or are you more interested in adding long-term value to your home with a higher quality unit? There is no right answer to these questions; it’s about what your home needs at the time.

Factors Affecting the Cost of the Gas Tankless Water Heater Installation

Gas tankless water heater installation can be more or less expensive depending on a few variables. The main cost components are labor costs, permit costs, tools, and the complexity of the job. Below is a list of the primary cost factors that will determine how much you pay for a gas tankless water heater installation.

  • Indoor vs. Outdoor – An indoor unit will require a vent to transport exhaust from the water heater to the outside of the house. Installing a vent costs around $250 – $600. An outdoor unit does not require a vent to be installed because the exhaust can escape directly outside.
  • Gas Line – If the contractor has to install or replace a gas line, it can add around $500 to $750 to the total cost of the installation.
  • Permit – This project almost always requires a permit. Permits for installing a gas tankless water heater cost between $100 – $500. Permit cost for a replacement unit is lower than for a new unit.
  • Complexity – If the installation is particularly complex or difficult it will cost more. One thing that makes an installation complex is if the contractor has to work in a hard-to-reach area like an attic, basement, ceiling, or crawl space. Another complicating factor that will increase the cost is if the project requires drywall removal and replacement.
  • Location – The area you live in will affect the cost of contractor labor. If you live in a particularly expensive area like the West Coast or parts of New England, the cost to hire a contractor will be higher than other parts of the country like the Midwest which tends to have a lower cost of living.

Gas vs. Electric Tankless Water Heaters

Electric and gas tankless water heaters both bring a lot of great qualities to the table along with various pros and cons.

Electric units are generally less expensive to buy and install, but gas units can last twice as long before needing to be replaced.

For a more detailed look at electric vs. gas tankless water heater costs and features, check out our full page on this topic.

Gas vs. Electric Tankless Water Heater Unit Cost

Electric tankless water heaters will usually have a lower upfront cost than gas tankless units. Even a whole-house electric tankless water heater will often cost under $1,000 – significantly less than the cost of a whole-house gas tankless water heater.

The problem is, however, that electric units generally don’t deliver as much hot water.

Gas vs. Electric Tankless Water Heater Installation Cost

Electric units have a much simpler installation than their gas counterparts, especially when a gas unit is installed inside and must be vented.

This means that electric tankless water heaters cost less to install.

Gas vs. Electric Tankless Water Heater Yearly Cost

The yearly operating costs for gas vs. electric units fluctuate based on the current price of fuel. A gas unit is almost always cheaper to run than an electric unit.

But not right now.

At the start of 2022, the cost of gas is significantly higher than normal, so an electric tankless water heater will have a yearly operating cost that is pretty close – not much higher and in some areas lower – than gas.

If you’re planning for the long-term, we believe that gas water heaters will have a lower operating cost over the next 10-15 years.

Gas Tankless Water Heater Repair Cost

Is your gas tankless water heater not working properly? The main symptom that something may be wrong with your water heater is if there is a drop in your hot water temperature, or if you’re not getting any heated water at all.

The list below covers the most common gas tankless water heater repair needs and cost estimates for parts and labor.

  • Flush/Cleaning – Even if your tankless water heater is working fine, it’s recommended to get your unit flushed at least once every year. This is because the water running through the system can leave mineral deposits and sediment buildup that could slow or clog the water flow. A water heater flush takes about half an hour for a plumber to do and costs about $150.
  • Water Softener Installation – Many homeowners choose to install a water softener to avoid the fast mineral buildup that comes from hard water. This is more of a preventative measure, because mineral buildup can cause major damage to the internal parts of a tankless water heater. Installing a water softener costs $800 – $2,000 or so for parts and labor, and can be done in 2 – 5 hours by a professional.
  • Heat Exchanger Replacement – The heat exchanger is one of the most important parts of a tankless water heater, and if it breaks, the replacement can be a bit pricey. Replacing the heat exchanger in a gas tankless water heater costs between $1,000 – $1,500 total for parts and labor. A large part of this cost is for labor as it can take 10 hours or more to replace. As a result, it’s often best to replace the unit rather than repair it.

Here are all common repairs and costs.

Gas Tankless Repair Costs
Repair Heater Type Parts & Labor Time
Cleaning Either $150 – $250 1-1.5 hours
Recirculation pump install Gas whole house $600 – $1,000 3-4 hours
Heat exchanger Gas $375- $600 3-5 hours
Ignition Gas $225 – $350 1-2 hours
Flame sensor Gas $190 – $315 1-2 hours
Gas valve Gas $265 – $485 2-3 hours
Venting issues Gas $125 – $500 1-3 hours
Condensate drain Gas $150 – $325 1-2 hours
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What Size Water Heater Do I Need?

This is a universally used chart showing how much water is needed for various applications:

  • Water-Saver Shower Head – 1.5 GPM
  • Standard Shower Head – 2.0 GPM
  • Standard Hand Sink – 0.5 GPM
  • Kitchen Sink – 1 to 2 GPM
  • Bathtub – 4 GPM
  • Dishwasher – 1 to 2 GPM
  • Washing Machine – 1 to 1.5 GPM

Which of these are likely to be in use at the same time? Add up the required GPM to determine water heater size.

For example, if a shower is in use (1.5 to 2.0 GPM) while the dishwasher is running (1 to 2 GPM) while a hand sink might also be used, you’ll need a minimum of 1.5 or 2 (shower) + 1 or 2 (dishwasher) + .5 (hand sink) for a total of 3.0 GPM to 4.5 GPM.

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