Should you make the switch to a tankless water heater?
The tankless question usually comes up at the worst possible moment, when the old tank has failed and there is water on the garage floor. The answer then has to be given in an afternoon rather than considered carefully. This post is for answering that question in advance. It sets a conventional tank heater and a tankless heater side by side on the six things a Columbia household notices, then it offers guidance on who might benefit the most from making the switch.
Running out of hot water
A tank heater holds 40 or 50 gallons, and when the second shower and the dishwasher run together, the tank empties and everyone waits. A tankless heater holds nothing; it heats water as it flows through, so it never runs out, and the only limit is how many fixtures can run at once, which is a sizing question rather than a capacity one. For a household of teenagers, or one with a soaking tub, this is usually the point that decides it.
What it costs to run
A tank heater keeps its water hot around the clock, reheating the tank every time it cools whether anyone is home or not, and that standby loss is the largest part of its operating cost. A tankless heater runs only while hot water is being used. The Department of Energy estimates that for homes using about 41 gallons of hot water a day or less, a tankless heater is 24 to 34 percent more energy efficient than a conventional tank, and 8 to 14 percent more efficient for homes using around 86 gallons a day. The saving arrives monthly, with a greater benefit for a large household than for a small one.
Where it lives
A tank heater occupies a floor footprint in a garage, a closet, or a crawl space, and in many Columbia homes that is space the household would rather have back. A tankless heater is about the size of a carry-on suitcase and hangs on a wall. In a crawl space that stays damp on the Midlands clay, or a garage that took water in the October 2015 floods, a wall-mounted unit also sits above the level water usually reaches, which a tank on the floor cannot offer.
How long it lasts
A tank heater lasts about 8 to 12 years, and the end usually arrives as a leak, because the steel tank corrodes from the inside until it fails. A tankless heater lasts about 20 years with regular maintenance, roughly twice as long, so one unit serves the period in which a tank would be replaced twice. That difference is part of the arithmetic on the higher purchase price, and it is also why a tankless unit’s yearly descaling flush matters (skipping it shortens the life and voids many warranties.)
What winter does
This is the one point where the tank has an edge, and it deserves plain mention. A tankless heater’s flow rate depends on how much it has to raise the water’s temperature, and the water arriving at a Columbia home in January is colder than in July. A unit sized for a summer shower can run short when two showers and the dishwasher run together on a cold morning, so a tankless heater is sized for the cold-water season and the household’s peak use rather than its average.
Columbia’s winters are mild enough that this is a sizing question rather than a valid reason to avoid tankless, but it is a question the estimate has to answer.
The cost and what it depends on
A tankless heater costs more to buy and install than a tank, and the gap depends on the fuel. A gas tankless heater draws several times the gas a tank heater does while it runs, so it often needs a larger gas line and its own venting, which is plumbing work our tankless water heater team handles. An electric tankless heater draws a large amount of current when it fires and frequently needs new circuits or a panel with more capacity than an older Columbia home has, and that part of the job belongs to a licensed electrician, so a home without gas service should plan for that evaluation before choosing tankless. Financing is available for either type, and members of the Cloud 10 Membership receive 5 percent off water heaters.
Who should switch
- A household that runs out of hot water regularly, or that will grow.
- A home with natural gas service, where the switch is a plumbing job rather than a plumbing and electrical one.
- A homeowner planning to stay long enough for the lower operating cost and the longer life to pay back the premium.
- A home where the tank sits in a crawl space or a garage that has flooded, where a wall-mounted unit is a clear improvement.
Who should not
- A small household with modest hot water use and a tank in a dry interior closet, where the premium is hard to justify.
- A home on very hard well water without treatment, since scale collects in a tankless heat exchanger faster than in a tank.
- A home without gas service and with an older 100-amp panel, unless the electrical upgrade is already planned for other reasons.
- A homeowner who expects to sell within a few years.
In those cases when a new tank heater is the sensible choice, our water heater team will say so.
Deciding on a dry day
2nd Wind Heating & Air Conditioning has served Columbia since 1985. If your tank heater is past ten years, or sits somewhere that has flooded, schedule a consultation online or through the website chat at any hour. The technician will measure the household’s peak hot water use, check the gas line, and lay out the tankless and tank options side by side with the reasoning behind each.