While technically possible if you have advanced DIY skills, installing a tankless water heater yourself is not recommended for beginners. It involves complex plumbing, specialized electrical work, and dangerous gas fitting.
Installing a tankless gas water heater is a difficult and sometimes dangerous process. We highly recommend having a licensed professional plumber handle this job. Be sure to follow all local plumbing and electrical codes when sourcing and installing parts for your new water heater.
Tankless water heater installation costs between $1,404 and $3,899 for your home, depending on unit size and setup. The fuel type you choose shapes your upfront and utility costs, with electric lower-priced and solar earning tax credits.
The primary drawbacks of tankless water heaters are their significantly higher upfront purchase and installation costs, restricted flow rates that can struggle to supply multiple high-demand fixtures simultaneously, and mandatory annual maintenance to prevent scaling.
Plumbers often hesitate to recommend tankless water heaters because they act like high-performance sports cars. Unlike traditional tank models that are "workhorses" and can function while mostly ignored, tankless units require precise installation, regular maintenance, and are highly sensitive to mineral buildup.
For larger households, multiple showers, laundry, and dishwashing may run at the same time. Hot water demand could reach 10–12+ GPM. A high-capacity tankless water heater—or even two units installed in parallel—may be the best solution.
In freezing temperatures, condensate produced by a condensing tankless hot water heater can freeze inside the drain line, which can cause leakage, operation issues or shutoff. To help keep your indoor tankless water heater from freezing, use a direct vent exhaust & intake system.
A gas tankless water heater (natural gas) is only marginally cheaper to operate than an electric tankless water heater due to the exceptionally high thermal efficiencies of the electric units (99%+).
100-Pound Tanks
If you do not have your 100-pound tank filled on-site, it needs to be 3 feet from all building openings and 5 feet away from any ignition source, direct vent intakes and mechanical air intakes.
Gas tankless water heaters installed by December 25, 2025, might qualify for a $600 federal tax credit. The government is offered this 30% credit through December 2025 to help cover the cost of the unit and its installation. This tax credit comes from the 25C Energy Efficient Home Improvement Tax Credit program.
On average, tankless water heaters last around 15 to 20 years, though some high-quality models can last even longer. This is significantly longer than traditional tank-style water heaters, which usually last about 8 to 12 years.
Home Depot’s total cost for a tankless water heater, including both the unit and standard installation, ranges from $𝟐,𝟒𝟎𝟎 to $𝟓,𝟒𝟎𝟎. Out of this total, labor alone typically accounts for $𝟔𝟎𝟎 to $𝟏,𝟖𝟓𝟎, though complex retrofits can push that labor number higher.
You can see that, in a typical gas system, a tankless water heater with a capacity of 199,900 BTU will require a 1-inch pipe size for a 20 ft branch length (based on the 0.3 in w.c. pressure drop in Table 2). The same appliance would require just a ½” pipe size based on Table 4 the 3.0 in w.c. pressure drop.
Here are some common reasons why your tankless water heater might not be working and how you can troubleshoot these problems.
Here is a simple way to decide: Choose Navien if you want the highest efficiency, longest warranty, and built-in recirculation. Choose Rinnai if you have a large household and need the highest flow rates. Choose Rheem if you want a reliable brand at a lower price point.
Plumbers often hesitate to recommend tankless water heaters because they act like high-performance sports cars. Unlike traditional tank models that are "workhorses" and can function while mostly ignored, tankless units require precise installation, regular maintenance, and are highly sensitive to mineral buildup.
This problem usually comes down to capacity, heat production, or mixing issues inside your plumbing system. Sometimes the fix is simple, like adjusting your water heater temperature or flushing out sediment. Other times you may need a new mixing valve, an element replacement, or a different size water heater.
The cheapest way to heat a house depends on your local utility rates and climate, but natural gas furnaces offer the lowest monthly operating costs. If gas isn’t an option, high-efficiency electric heat pumps provide the cheapest continuous heating.
Yes, you should drip both hot AND cold. Otherwise, the area inside the tankless water heater between the cold water line and the heating element can freeze up and burst (happened to me in 2021 freeze). If you drip both slowly, it ensures all water is running through all the lines.
Yes, you should turn off your tankless water heater when the water to your home is off. This prevents the unit from accidentally firing up or drawing power to a dry system, which can cause significant and costly damage to the internal heating elements or heat exchanger.
Winterizing a tankless water heater (whether in an RV or a home) prevents trapped water from freezing and cracking the heat exchanger. The process requires isolating the unit, completely draining all internal water, and flushing the lines with non-toxic, food-grade RV antifreeze.
If a standard showerhead is fitted, it will use around an extra half a gallon each minute, accounting for a 25-gallon emittance every 10 minutes, or 50 gallons throughout a 20-minute shower. *1 gallon = 4.54 litres.
A tankless water heater usually goes cold mid-shower because the water flow drops below the heater's minimum activation threshold, or the system is overloaded by using too many fixtures at once. It can also happen if sediment blocks the filter or the unit is improperly sized.
Bath is always doable with tankless, you don't have to open the faucet all the way. If the tankless can't deliver water that's hot enough, just slow it down. Bathtub faucets are often much quicker than 8GPM so a tankless that's only 8GPM won't get water out at its max heat.