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How Much Does Tankless Water Heater Installation Cost in Phoenix?

August 29, 2023

We all know how vital it is to have instant hot water access in your home. Finding the right unit and the money to replace it, however, is its own story.

For Arizonians, you can expect to pay between $1,000 to $2,700+ to install a new tankless water heater.

The best way to determine your tankless water heater installation cost is to work directly with a trusted plumbing company, like Patrick Riley | Isley’s. Below, we walk you through new tankless water heater installation cost details and replacement options. The cost is affected by a number of factors:

  • Size (flow rate) of the unit
  • Water heater type
  • Fuel type (gas or electric)
  • The plumber you hire

Want to skip the tankless water heater installation guide and get a free quote today? Call Patrick Riley | Isley’s for a free quote and professional assessment of your home.

What Affects Your Tankless Water Heater Installation Cost?

Price Factor #1: The Size (Flow Rate) of Your New Unit

Unlike tank water heaters, tankless water heaters don’t have a reserve for water. Instead, water flows through the heat exchanger on demand. Because of this, the “size” of a tankless water heater is determined by hot water flow rate (gallons per minute (GPM)).

The higher the flow rate, the more your tankless water heater installation costs will be.

The flow rate you need for your home will depend on the overall flow rate of all the water appliances you use at the same time.

For example, if you want to use the laundry room sink at the same time the dishwasher is running, you’ll need a flow rate that equals or is greater than the flow rate of your kitchen sink + the flow rate of your washing machine. That can be confusing, right? A trusted plumber can provide you with the most accurate estimate of the flow rate you need.

The Average Flow Rate of Typical Appliances:

  • Bathroom faucet: 0.5–2.5 GPM
  • Showerhead: 1–3 GPM
  • Washing machine: 1.5–2 GPM
  • Dishwasher: 1–2.5 GPM
  • Toilet: 2–3 GPM
  • Pressure Washer: 1–2 GPM
  • Garden Hose: 9–17 GPM

Price Factor #2: The Type of Tankless Water Heater

When it comes to tankless water heater installation cost and planning, you can choose home heaters (traditional units that heat water straight away) or point-of-use (POU) heaters (which can be installed alongside whole home heaters and serve as “checkpoints”). Both of these systems connect to the home’s pipe system.

Whole Home Units

Also known as centralized units, whole home tankless water heater installation provides hot water to all plumbing fixtures in your home, including

  • Showers and bathtubs
  • Sinks
  • Garden hoses
  • And more

Point-Of-Use (POU) Units

Unlike whole home units, POU tankless water heater installation provides hot water to a single appliance or area (like a bathroom or laundry room). They may seem like more complex systems, but POUs can also be very convenient and thus save on water over time. There are also compact devices that can be installed inside a cabinet or corner of the room.

What Type of Tankless Heater Is Best to Install in My Home?

Great question! Whole home tankless water heater installation is best for most Arizona homes, and it may be the most cost effective. However, you may need to pair a whole home unit with one or several POU units if your home has

  • Hot water fixtures that are too far from the whole home unit
  • Appliances with high flow rates, including
    • Hot tubs and spas
    • Bidet toilets
    • In-home urinals
    • 3/4" sink faucet
    • And more

The tankless water heater installation cost for POU units is generally lower than whole home units because they’re smaller and provide less hot water output. However, if you’re installing multiple POU units or installing a POU unit in conjunction with a whole home unit, you can expect increased tankless water heater installation costs. If you’re unsure of what your home needs, contact Patrick Riley | Isley’s to schedule an inspection and free quote for your home.

Price Factor #3: The Unit’s Fuel Type

One big factor that impacts tankless water heater installation costs is the power it runs on. The two primary fuel types of tankless water heaters are gas and electric. Gas tankless water heater installation is more expensive, but monthly operational costs are lower.

Let’s break down the tankless water heater installation costs for each type of power.


If you already have gas lines, you can get a cheap replacement. If not, gas installations can be very expensive because of additional costs like these:

  • Gas line installation: If you want a gas water heater but don’t have a gas line, it will need to be installed. Installing a gas line can increase your tankless water heater installation cost by $3,000+.
  • Gas line extension: If your home has access to natural gas but a line isn’t close enough to your tankless water heater, installation costs will increase because the gas line will need to be extended.
  • Vent installation: Gas water heaters actually produce gasses through the combustion process; they need to vent to the exterior so these gasses can be expelled outside. If your home hasn't had a gas water heater before, a plumber will likely need to cut through walls to install this venting, increasing your tankless water heater installation cost.


Electric water heaters are cheaper to install, as they run on your home’s electricity rather than gas lines. In terms of electric water heater installation costs, you can expect increased pricing for

  • An electrical panel upgrade: Your home’s electrical panel may not be powerful enough to support the load of a new water heater. If you need an upgraded electrical panel, it could cost a couple thousand dollars.

Determine what your home needs and an exact cost to install your new tankless water heater by calling Patrick Riley | Isley’s today.

Price Factor #4: Your Choice of Plumber

Tankless water heater installation costs and planning can be complicated, and you want someone who has the skills and knowledge necessary to do the job correctly and safely.

Here are some tips for finding a great plumber:

  • Look for their license and insurance info. You can do this by either checking for their license number on their website or by checking out the BBB (Better Business Bureau). All companies that have a profile on the BBB have a verified license and insurance.

Get a written estimate. If a contractor won’t provide you with a written estimate, it should be a warning sign. A written estimate protects you from any unknown or hidden fees and helps you avoid any surprises in cost after your installation has been completed.

Ready to install a tankless water heater? Hire a Phoenix pro!

One of our expert plumbers will provide a free in-home estimate for tankless water heater installation costs and ensure that your unit is installed correctly. Short on cash now? No problem! Check out our flexible financing options to see if you qualify for an easy online payment plan.

Written by: Patrick Riley Cooling, Heating, & Plumbing

Originally published: March 06, 2018

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By Ty Lindsay

Ty Lindsay is the Director of Field Operations at Patrick Riley | Isley’s and a 15-year veteran of the plumbing and HVAC trades. In 2010, Ty earned his Journeyman’s plumbing license. He became a Master Plumber five years later and earned his Journeyman HVAC technician’s license that same year. Ty’s breadth of knowledge in plumbing and HVAC includes both residential and commercial work. He’s been a loyal member of the Patrick Riley | Isley’s team since 2016.