What Is the Average Cost to Put In a Tankless Water Heater?

What makes up the total installation cost?

When you browse home improvement stores or online retailers, the price tag on the heater looks simple. You see a compact metal cabinet and imagine an easy afternoon swap. In reality, the physical heater is only one part of the total investment. The full cost divides into two distinct categories: the equipment you buy in a box, and the labor required to make your house safe to operate it.

For a compact heater serving a single sink, the hardware is modest and the hookup is relatively quick. For a whole-house unit that can run a dishwasher and two showers at once, the hardware is only the starting point. Equipment cost scales with water flow speed in gallons per minute (GPM). The larger your household, the bigger the heating engine you need.

Labor is where homeowners face the biggest price swings. A professional does not simply mount a box on the wall. They must evaluate how water enters your home, how much fuel or power is available, and how exhaust leaves the building. In an existing home, adapting older infrastructure to meet modern appliance demands takes hours of skilled work from licensed tradespeople.

Permits and inspection fees also add to the final invoice. Most towns require building permits for major water heater replacements to prevent water damage, carbon monoxide leaks, and electrical fires. Depending on where you live, local fees can add a noticeable amount to the final bill.

What does the installer actually do for that fee?

If you look at an installation quote and see labor as the largest charge, you might wonder why the technician charges that amount. Installing a tankless water heater touches three critical household systems: plumbing, energy delivery, and exhaust ventilation.

First, the technician must safely disconnect and drain your old water heater. A standard water tank holds forty to eighty gallons of water, weighing hundreds of pounds when full. Draining the tank, disconnecting gas or high-voltage lines, and hauling that heavy steel cylinder up basement stairs requires physical effort and proper disposal.

Next comes structural mounting and pipe work. Tankless water heaters hang directly on wall studs. The technician must level the unit, anchor it securely, and rework your home's water lines. Traditional tanks connect to water pipes at the top, while tankless units connect from underneath. That requires cutting into existing copper or plastic lines, soldering or crimping new fittings, and routing lines to the new location.

A reputable installer also adds isolation service valves directly beneath the unit. These specialized valves allow you to shut off water and flush the heating chambers once a year. Flushing clears away scale, which is the chalky mineral buildup left behind by hard water. Without these valves, cleaning your heater is nearly impossible.

Finally, the technician balances water pressure, checks for leaks, purges air from the lines, and verifies the pressure relief valve. Each step protects your home from water damage.

Why is replacing an old storage tank more expensive?

Swapping an existing tankless unit for a fresh one is straightforward because the supporting pipes and vents are already in place. Converting an older home from a storage tank to a tankless system is an entirely different project. This retrofit work accounts for the biggest price jump homeowners experience.

The primary factor is venting. Venting is the exhaust pipe carrying combustion fumes safely outside. When you burn gas to heat water, the combustion process produces hot exhaust gases and moisture. An old tank heater vents through a basic metal chimney that drafts upward naturally. Tankless gas heaters burn fuel at a much higher intensity, producing cooler, acidic exhaust that must be pushed outside using an internal fan.

You cannot vent a modern tankless gas heater into an old metal flue. The acidic moisture quickly rots older metal pipes and breaks down brick chimneys, creating fire and carbon monoxide dangers. Instead, the installer must cut new holes through an exterior wall or roof and run specialized, airtight pipe. Navigating this pipe through finished ceilings or crawl spaces takes hours of careful carpentry and plumbing. In tight utility spaces, such as those found when planning for the best heater for mobile home setups, venting clearances require strict compliance with manufacturer rules.

Piping locations also add retrofit labor. An old tank sat on the floor, but a tankless unit hangs on a wall. Relocating the heater to an exterior wall to shorten the vent path means extending water lines across the room, adding insulation, and routing a new drain line to carry away condensation.

Which costs more to hook up, gas or electric?

Both gas and electric tankless water heaters carry unique installation demands. Neither is universally cheaper to put in; the final cost depends on your home's current utility supply.

Gas tankless units require an enormous volume of fuel in a short burst. A standard storage tank burns thirty thousand to forty thousand British Thermal Units (BTU) per hour because it can heat water slowly over several hours. A tankless gas unit heats incoming groundwater instantly as it rushes past the burner, demanding eighty thousand to nearly two hundred thousand BTU per hour.

To supply that burner, your gas pipe must be wide enough. Most older tank heaters use a half-inch gas pipe. A whole-house tankless unit almost always requires a three-quarter-inch or one-inch pipe running directly from the gas meter. Replacing long runs of iron pipe through finished ceilings increases labor costs significantly. In some cases, the gas utility company must also swap your meter for a higher-capacity model.

Electric units avoid gas lines and exterior vents, but they place a heavy burden on your electrical system. A whole-house electric unit heats water using high-power elements. To operate safely, the unit requires a dedicated circuit, which is a separate wire and switch serving only one appliance. Many whole-house electric models require three or four separate 240-volt dedicated circuits.

If your home has a 100-amp or 150-amp electrical panel, it cannot power a whole-house electric tankless heater alongside your refrigerator, oven, and air conditioner. Installing the heater often forces a full service panel upgrade to 200 amps. Much like planning wiring when choosing the best electric heater for garage with thermostat needs, high-draw electric heaters require an electrician to verify total panel capacity before purchasing hardware.

What should you ask before signing a contractor quote?

Getting multiple written estimates helps protect your budget, but comparing bids is difficult when contractors price jobs differently. One technician might offer an attractive number that leaves out essential tasks, leading to change orders later. Another might present a higher total that includes every permit, pipe, and valve.

Before signing an agreement or paying a deposit, review these specific questions with each contractor:

• Does the quote include local building permits and inspection fees? Confirm that the contractor handles permit paperwork and scheduling rather than leaving surprise fees for you later.
• Can my existing gas line or electrical panel support this heater? Have the technician measure gas pressure or calculate your electrical panel load before agreeing to an equipment size.
• Are dedicated isolation service valves included in the plumbing labor? Verify that the quote includes flush valves under the unit so you can clean out mineral scale later.
• What venting material will you install, and where will it exit? Ensure the installer uses dedicated exhaust piping designed for tankless exhaust rather than reusing an old chimney flue.
• Does the price include draining, removing, and disposing of the old tank? Confirm that hauling away your old water heater is covered under the base labor fee.

What type of tankless heater fits your home best?

Selecting the right heater style depends on where you need hot water and how your home delivers power. For a busy household wanting endless hot water across multiple bathrooms, a whole-house system is the natural choice. These systems carry higher installation expenses due to fuel and venting demands, but they supply enough hot water to run multiple fixtures simultaneously.

If you only struggle with cold water at a single distant fixture, you do not need to repipe your entire house. A compact point-of-use electric heater fits directly under a bathroom vanity or kitchen sink. These small units warm water right at the faucet, cutting down waiting times and saving water. Point-of-use units require much less electrical current, keeping installation quick and affordable.

For detached garages, cabins, or temporary outdoor setups, a portable propane heater offers another practical option. These units run on portable propane tanks and vent easily into open air, making them useful for outdoor showers or owners planning the best heater for van life travels.

Before buying any heater, verify your groundwater temperature and the water flow speed in gallons per minute (GPM) your home requires. Check the equipment label for recognized safety marks, such as UL or ETL listings, to ensure the appliance meets established safety standards.

1

Westinghouse 11kW Tankless Water Heater Electric 240V, Wifi, ETL, Gray

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  9.1
• Brand
  Westinghouse

Key specs2

Electrical Circuit Requirements

Dedicated 60A double-pole breaker with 8 AWG wire at 240V

Water Flow and Capacity

Starts heating at 0.53 GPM and reaches 2.6 GPM with a 62-degree inlet and 105-degree outlet target, designed for a single shower or sink point.

Pros & cons42

Pros

• Delivers up to 2.6 GPM at a 43-degree rise, sufficient for single-point shower use
• Connects to WiFi for mobile app monitoring and voice adjustments via Alexa or Google Home
• Retains the previous temperature setting after power interruptions via automatic memory
• Features a removable inlet filter and rotor that can be rinsed by hand for routine scale upkeep

Cons

• Demands a dedicated 60A double-pole breaker and 8 AWG wiring at 240V, which may require an electrical panel upgrade
• Limited to a single active fixture at 2.6 GPM, making it unsuitable for multi-bathroom simultaneous use

2

14L Tankless Water Heater Propane with Digital Display 3.66 GPM

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  8.9
• Brand
  Baococo

Key specs2

Fuel and Thermal Output

85,300 BTU/hr propane burner with up to 3.66 GPM flow

Outdoor Safety Systems

• Flame failure cutoff and low-flow ignition lockout
• Antifreeze protection and dry combustion shut-off
• High water pressure relief valve

Pros & cons42

Pros

• Delivers 85,300 BTU per hour with up to 3.66 GPM flow without tapping into household electrical panels
• Operates on liquid propane, making it functional for off-grid cabins, camping, and outdoor pet washing
• Features six safety cutoffs including flame failure, antifreeze, dry combustion, and high water pressure relief
• Includes an attached shower head with a one-button shut-off to manage water consumption

Cons

• Requires outdoor placement or dedicated combustion venting to prevent hazardous gas exhaust accumulation
• Dependent on a continuous liquid propane fuel supply and proper gas regulator hookups

3

ECOAPTUNIT 110V Tankless Water Heater Electric, 3000W

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  7.6
• Brand
  ECOAPTUNIT

Key specs2

Point-of-Use Flow Rate

Produces a 35-degree temperature rise at 0.5 GPM or a 21-degree rise at 0.3 GPM, restricted to low-flow handwashing sinks.

Breaker and Wire Spec

Requires dedicated 32A breaker and 2.5 mm² wiring at 110V

Pros & cons42

Pros

• Compact 4.53-inch square profile fits neatly under tight kitchen and bathroom sink cabinets
• Plugs into a standard 110V electrical supply without requiring a high-voltage 240V line installation
• Provides immediate localized warm water with up to 98 percent thermal efficiency
• Features IPX4 water resistance and isolated electrical pathways to guard against moisture contact

Cons

• Delivers only 0.3 to 0.5 GPM flow, making it completely inadequate for showering or full-home fixtures
• Requires a dedicated breaker rated for at least 32 amps and 2.5 mm square wire to prevent circuit overloads

4

Tankless Water Heater Electric, 3000W Tankless Electric Water Heater 110V,

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  7.5
• Brand
  xwdzswgs

Key specs2

Under-Sink Dimensions

4.31 x 4.31 x 7.85 inches with 1/2-inch NPT plumbing fittings

Fixture Suitability

Engineered specifically for low-flow handwashing sinks in RVs, small apartments, or half baths; unsuited for shower demands requiring 1.8 GPM.

Pros & cons42

Pros

• Ultra-compact footprint under 8 inches tall preserves space inside RVs and compact lavatories
• Operates on standard 110V household current to avoid costly 240V high-amp service conversions
• Features an LCD digital screen that toggles between Fahrenheit and Celsius by holding the power button
• Incorporates automated shut-off protection against dry burning, overheating, and electrical leakage

Cons

• Output is strictly limited to hand-sink flow rates and is explicitly unsuitable for standard 1.8 GPM showers
• Requires dedicated 13 AWG (2.5 mm²) wiring on a 32A minimum circuit rather than standard 15A or 20A branch outlets

5

Westinghouse 14kW Tankless Water Heater Electric 240V, Wifi, ETL, Gray

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  7.5
• Brand
  Westinghouse

Key specs2

Electrical Circuit Requirements

Dedicated 60A double-pole breaker with 6 AWG wire at 240V

Simultaneous Fixture Capacity

Reaches 3.4 GPM with incoming 62-degree water heated to 105 degrees, providing enough volume to supply two active fixtures at the same time.

Pros & cons52

Pros

• Generates 3.4 GPM at a 43-degree rise, allowing simultaneous hot water delivery across two fixtures
• Enables wireless temperature monitoring and remote mobile control via Alexa, Google Home, and app connectivity
• Memory setting retains programmed water temperature automatically following an electrical power outage
• Separate water and electrical pathways combine with IPX4 splash resistance for bathroom installation safety
• Removable water filter and rotor allow quick semi-annual cleaning to prevent mineral scale build-up

Cons

• Requires a heavy-duty dedicated 60A double-pole breaker with heavy 6 AWG copper wiring at 240V
• Maximum 3.4 GPM capacity cannot support simultaneous whole-house use in homes with multiple bathrooms and appliances running together

Last update on 2026-10-11 / Affiliate links / Images, Product Titles, and Product Highlights from Amazon Product Advertising API

FAQs

Why does labor often cost more than the heater itself?

Labor charges reflect the skilled work needed to adapt your home's core utilities safely. A technician must reroute plumbing lines, cut new exterior vent paths, and often upgrade gas pipes or run heavy electrical wiring. These tasks require licensed tradespeople, multiple hours of physical labor, and strict compliance with local building codes.

Do energy bill savings make up for the upfront cost?

A tankless unit saves energy by warming water only when you open a tap instead of keeping a large storage tank hot all day. While these efficiency gains will lower your monthly utility bill, the upfront installation fee is significant. Most homeowners make the switch to enjoy endless hot water and recover floor space rather than strictly for fast financial payback.

How does cold winter weather affect your installation cost?

Incoming tap water is significantly colder during winter in northern climates than in southern states. Because the heating unit must work much harder to lift freezing groundwater to a comfortable shower temperature, northern homes require higher-capacity units. A larger heating capacity demands wider gas lines or larger electrical circuits, which increases overall project costs.

When should you stop work and call a licensed professional?

Stop work immediately and contact a professional if your project involves opening the main electrical panel, cutting into gas supply lines, or routing combustion vents through walls. Handling high-voltage wiring or natural gas carries serious risks of electrical shock, fire, and carbon monoxide leaks. A licensed plumber or electrician ensures your installation is completely safe and fully permitted.