Tankless Water Heaters: Installation, Sizing and Pricing

A tankless water heater fires a burner the moment a hot tap opens and shuts it off when the tap closes. There is no tank to run out and no standby loss from keeping 50 gallons hot all night. In exchange, the unit needs enough gas, the right venting, a drain for condensate and an annual descaling in Central Ohio’s hard water. It is a good choice for many homes and the wrong choice for some. This page explains how we size it, what it needs from your house, and what it starts at installed.

When tankless is the right choice

• You run out of hot water with a tank and do not want a larger one. A correctly sized tankless unit keeps up as long as the tap is open.
• You want the floor space back. A wall-hung unit is the size of a small suitcase.
• You want the longest service life. The Department of Energy notes most tankless units last more than 20 years, against 10 to 15 for storage tanks, and heat exchanger warranties are 12 to 15 years.
• You want to reduce gas use. The Department of Energy reports tankless units can be 24 to 34 percent more energy efficient than storage tanks in homes using 41 gallons or less of hot water a day, and 8 to 14 percent more efficient at about 86 gallons a day.

It is a weaker fit when the gas meter and piping would need a large upgrade, when there is no practical drain for condensate, or when a 50-gallon gas tank starting at $1,949 already serves the household. The tank versus tankless comparison walks through the trade-offs.

What the installed price includes

• A condensing gas tankless unit sized to your flow class, with the manufacturer heat exchanger warranty for the tier: 12 or 15 years.
• Standard wall mounting in the existing heater location, new water connections and a new gas connector with sediment trap.
• PVC intake and exhaust venting through the nearest exterior wall, up to the standard run, with a compliant termination, and a condensate line to an accessible floor drain.
• Removal and haul-away of the old tank, and capping of the old flue where the tank used a chimney.
• The permit, pulled by us and passed through at cost.
• Startup testing: purge, gas pressure under full fire, combustion check, and flow and temperature verification at the farthest fixture.
• A workmanship warranty of 1, 2 or 5 years by tier.

Preferred and Authority include the tankless isolation and service valve kit, which makes annual descaling a 45-minute job instead of a half day. Authority adds a drain pan, a leak sensor with automatic shutoff valve and the first year of the maintenance plan.

Three tiers for gas tankless

Estimated installed prices for Central Ohio. Your online estimate is based on the installation details you provide. A technician verifies conditions before work begins, and if anything changes the price we show and explain the difference before proceeding.

Labor-only installation of a customer-supplied tankless unit starts at $2,249, with the same gas, vent and condensate verification.

Sizing: gallons per minute at a 78°F rise

A tankless unit is rated by how many gallons per minute it can heat by a given number of degrees. The bigger the temperature lift, the lower the flow. In Central Ohio the winter inlet is about 42°F, and a 120°F setpoint means the unit must raise the water 78°F. Manufacturers publish flow at that rise, and it is well below the headline number on the box. We size to the coldest month so the unit still keeps up in February. Add the fixtures you expect to run at once, look up the flow at 78°F, and choose the class that covers it with margin. Our size calculator does this for you, and the sizing guide explains the method.

Gas line sizing

This is the item most likely to change the price, and the one most often skipped by low bidders. A tankless unit draws several times the gas of a standard tank while running. Whether the existing line can deliver that depends on pipe diameter, run length from the meter, the number of fittings and every other appliance on the same line. We measure and calculate on site. If the line is adequate, nothing changes. If it is not, a gas line upsize is quoted before you approve anything. A tankless unit installed on an undersized line short-cycles, throws ignition errors and never delivers its rated flow. Verified on site

Venting and condensate

Condensing tankless units wring extra heat out of the exhaust, which makes the exhaust cool enough for PVC and produces a steady drip of acidic condensate while the unit runs. Both intake and exhaust are piped to outdoors, usually through the rim joist near the unit. Termination clearances to windows, doors, meters and grade follow the installation manual. The condensate needs a drain. A floor drain within reach is included. A condensate pump to lift it to a laundry standpipe is $229, and a neutralizer cartridge to protect the drain is $149 and is required in some jurisdictions. New PVC beyond the standard run is $299 per 10 feet.

Descaling and scale protection

Hard water leaves mineral scale on the heat exchanger. On a tank it settles to the bottom; on a tankless it coats the narrow passages where heat transfers, and the unit runs hotter until it faults. The answer is an annual descale that circulates a mild acid solution through the heat exchanger. With isolation valves installed, it is a 45-minute visit at $299. A scale-reduction pretreatment cartridge upstream of the unit is $399 and slows buildup between services. See the descaling guide.

What can change the price

Included

Part of the option you chose.

Required

This condition must be corrected for the proposed installation to be safe and code-compliant.

Recommended

Not required for the heater to operate, but it improves protection or serviceability.

Optional

A comfort or protection upgrade. Your choice.

Requires field verification

Priced after a technician confirms the condition on site.

Our process

1. Size it online

   The size calculator picks a flow class from your fixtures and the quote builder shows the starting-at price by tier.

2. Book at least 48 hours out

   Choose a two-hour window. We stage the unit and materials before the visit.

3. On-site verification

   The technician measures the gas line, plans the vent route and termination, locates the condensate drain and outlet, and confirms an estimated installed price in writing.

4. Installation and startup

   Remove the old tank, mount the unit, run venting and condensate, connect gas and water, then fire it under full load and verify temperature and flow at the farthest fixture. You receive photos, serial numbers, the permit record and warranty terms.

Safety and code notes

Work follows the 2024 Ohio Plumbing Code, the Residential Code of Ohio, the Ohio fuel gas provisions and the manufacturer’s installation instructions, which govern gas sizing, vent material and termination clearances. Gas pressure is verified under full fire on every tankless install. Work is performed by appropriately licensed personnel or partners.

Where we install tankless water heaters

All of Central Ohio, from Columbus and the inner suburbs to Delaware, Lancaster and Newark, on the 48-hour lead time. See the service area page.

See your tankless price

Size your unit, see the installed starting price by tier with permit and haul-away included, and book a window at least 48 hours out. Or call 844-792-8374, answered 24/7.

Get My Water Heater PriceCall 844-792-8374