Why the unit price is only part of the cost
A tankless heater needs the right gas supply or electrical capacity, a proper vent, a drain for condensate and the right plumbing connections. A replacement of a tank heater often needs several of these upgraded.
| Factor | Why it matters | Typical effect |
|---|---|---|
| Fuel type | Gas units need venting and gas supply, electric units need heavy circuits | Large. |
| Gas line size | Tankless units draw more gas at once than tank units | Moderate to large. |
| Venting | Special vent pipe and a clean route outside | Moderate. |
| Electrical service | Electric units may need a panel upgrade | Large. |
| Water quality | Scale protection such as a softener | Moderate. |
| Location | Garage, closet or exterior wall mount | Small to moderate. |
Our tankless water heater page explains the work in more detail.
Gas or electric in an Arizona home
Gas units deliver strong flow for a whole house but need a vent and enough gas capacity. Electric units are simpler to vent and often fit a small space, yet they draw heavy current, so the panel and wiring decide whether they are practical.
Incoming water is warm much of the year in Arizona, so a tankless unit has less temperature rise to supply than in cold climates. Sizing still matters because several fixtures may run at once. A proper sizing check counts the fixtures you use together.
Hard water changes the math
Scale is the main enemy of a tankless heater. It forms inside the heat exchanger and cuts flow and efficiency. Many installs include isolation valves so the unit can be flushed, and some include a softener.
A softener adds cost up front but protects the unit. See water softener and filtration for how to check your hardness first. A flush once a year is part of owning a tankless heater.
Want a tankless quote?
Call us with the fuel type, the location and the number of bathrooms. We will explain what your house needs.
Call (480) 741-9332What a quote should include
Compare written quotes line by line. A clear quote lists these items.
- The make and model of the heater and its rated flow.
- Any new gas line, vent, circuit or panel work.
- Isolation valves, a drain pan and a pressure relief line.
- Removal and disposal of the old tank.
- Permit and inspection costs if required.
- Warranty terms on parts and labor.
Tank or tankless: a short comparison
A tankless unit is not always the better buy. A tank heater costs less to install and is simpler to service, while a tankless unit saves space and does not run out during a long shower.
If your tank has failed and you want a straight swap, see water heater replacement. If you have no heater yet or are moving it, water heater installation covers the new setup.
The tax credit has ended
The federal credit under Section 25C applied to improvements made through December 31, 2025. For a tankless install in 2026 it no longer applies. Do not let a quote lean on a credit that has expired.
Utilities and manufacturers sometimes offer rebates that change. Ask your utility and the manufacturer, and confirm any rebate in writing before you buy.
Operating cost after the install
The purchase and installation are one part of the cost. The rest is what the heater spends over its life. A tankless unit avoids the standby loss of a tank, so it often uses less fuel in a home with modest hot water use.
The saving shrinks in a large household with many back-to-back showers. Ask for the unit's efficiency rating and compare it with a tank of the same fuel. Gas units also need annual care, so include service in your estimate.
Maintenance that protects the investment
A tankless heater is a precise machine. A little yearly care keeps it from throwing error codes.
- Flush the heat exchanger.Circulate white vinegar or a descaling solution through the unit using the isolation valves.
- Clean the inlet filter.Remove and rinse the small screen where water enters.
- Check the vent.Look for blockage, damage or loose joints in the exhaust pipe.
- Test the pressure relief.Confirm the relief line is clear and unobstructed.
Skipping a flush is the most common reason a tankless heater loses output in hard water.
Local note: the water hardness report that matters
EPCOR's water quality report for its San Tan system lists hardness of 15 to 18 grains per gallon from groundwater. That is about 257 to 308 milligrams per liter, which the USGS classes as very hard. The report covers the system and does not name every neighborhood, so confirm which system serves your address.
The Town of Florence report does not list hardness, so Florence customers should test their tap. In Coolidge, the Arizona Water Company report also gives no hardness figure. In all three cases, a measured number should drive the decision on scale protection.
We quote tankless work for homes in San Tan Valley and Coolidge too.
Source type: EPCOR San Tan system water quality report and USGS hardness classification (utility and federal sources). The hardness range is stated according to the EPCOR report, and the classes according to the USGS.
Questions readers ask
It depends on your measured hardness. Test the tap and consider protection if the water is hard.
Sometimes. Gas size, venting and power often need upgrades.
No. The Section 25C credit applied through December 31, 2025.
Pinal County Building Safety handles permits there since July 1, 2026. Confirm with them.