Why avoid a tankless water heater?

Author: Dr. Sarah Nolan  |  Last update: Friday, June 12, 2026

Unlike traditional storage water heaters, tankless units may not be able to meet your home's hot water needs if you have multiple outlets running simultaneously. This is because the flow rate of a tankless unit may not be high enough to support multiple uses of hot water at the same time.

Why don't more people use tankless water heaters?

  • Higher Initial Costs : Tankless systems typically have a higher upfront cost compared to traditional tank water heaters.
  • Installation Complexity : Installing a tankless system can be more complicated, which may require changes to gas lines or electrical systems.
  • Limited Flow Rat

What is the downside of a tankless water heater?

Before you commit to buying a tankless water heater, the primary drawbacks to know include: Higher upfront costs. Tankless water heaters are, on average, quite a bit more expensive to buy and install than tank water heaters. Access to fuel.

What do plumbers think of tankless water heaters?

St Paul Pipeworks plumbers advise against purchasing tankless water heaters from big box stores or online retailers, as homeowners often lack the expertise to determine the correct sizing for their specific needs. Many negative reviews about tankless systems stem from improper sizing or piping installations.

Is it worth switching to a tankless water heater?

Switching to a tankless water heater can help you save on your energy costs, with potential savings of up to 50%, according to the U.S. Department of Energy. Additionally, tankless water heaters are reported to be 24% to 34% more energy efficient than storage tank water heaters by the same source.

Pros And Cons Of Electric Tankless Water Heaters

Can I replace my 40 gallon water heater with a tankless water heater?

Absolutely! In fact, tankless water heaters are becoming the standard for new home construction because of the energy efficiency.

What is not a benefit of a tankless water heater?

A tankless water heater cannot provide hot water faster than its ability to heat the water. While a tank unit can provide hot water for multiple uses at once, a tankless unit might not be able to support simultaneous usage, such as washing dishes, taking a shower and running a washing machine all at once.

What is the lifespan of a tankless water heater?

Tankless water heaters usually last for around 15-20 years before they need to be replaced, but they may need replacing sooner if they start to break down or lose efficiency. Some common signs your tankless water heater needs to be replaced include: Low water pressure. Water doesn't get hot.

Is there an IRS tax credit for a tankless water heater?

The federal tax credit for tankless water heaters in 2024 is an excellent opportunity for homeowners to save money while investing in energy-efficient water heating solutions. This tax credit is effective from January 1, 2023, to December 31, 2032.

Where should a tankless water heater not be installed?

Keep your water heater away from outside elements

If your tankless heater is exposed to extremes weather conditions, it will run a greater risk of premature failure. So, make sure your appliance is away from doors and windows, and never installed in the garage or basement.

When not to get a tankless water heater?

Electric Tankless Water Heaters

They're less expensive than gas-powered ones but aren't efficient if you run multiple hot water devices. They may struggle to keep up with multiple appliances at the same time.

Can you take a long hot shower with a tankless water heater?

While a tankless water heater will deliver an unlimited stream of hot water, they struggle to deliver a lot of hot water at one time. So while you might be able to take 100 showers in a row if you have the dishwasher, washing machine, and shower going at the same time you might have problems.

Is hard water bad for tankless water heaters?

Scale buildup can reduce the efficiency — and even shorten the lifespan — of many items in a home. Tankless water heaters are particularly sensitive to hard water, but so are dishwashers, ice-makers and washing machines.

Is there a downside to a tankless water heater?

Cons: The upfront cost is higher than tank storage— but tankless water heaters last much longer, so you even out in the long run. They require more maintenance than tank storage— but this is typically just an annual flush to remove any built-up sediment. Areas with hard water can lessen their lifespan.

Can multiple people shower at the same time with a tankless water heater?

A: Yes, but depending on the wattage of your unit, and the temperature you set, the pressure may go down.

Can you replace a 50 gallon water heater with a tankless water heater?

A 50-gallon water heater should be replaced with a tankless system with a 10 GPM flow rate just to be safe. Selecting the right flow rate ensures you won't experience cold showers or excessive energy costs. Proper sizing optimizes performance, providing hot water on demand without unnecessary waste.

What is the tax credit for tankless water heaters in 2024?

Homeowners can receive a tax credit of 30% of the project cost, up to $2,000, for Heat Pump Water Heaters installed between January 1, 2023, and December 31, 2032. Gas Storage Water Heaters, Tankless Gas Water Heaters, and Boilers also qualify for a tax credit of 30% of the project cost, up to $600.

What category appliance is a tankless water heater?

Tankless water heaters don't always fit into one category. Many of these appliances are Category IV, condensing with induced draft. Some fall into Category III, induced draft with higher temperature non-condensing flue gases.

Can you write off a new hot water heater?

You can claim 30% of the project cost, up to a $2,000 maximum credit. Heat pump water heaters that have earned the ENERGY STAR are eligible for this credit. You can find a list of ENERGY STAR certified models here.

Do tankless water heaters need to be flushed every year?

Over time, a tankless water heater may accumulate mineral build up which can erode the walls inside your tank's heating chamber. To properly maintain and clean your tankless water heater, it's important to flush those mineral deposits at least once a year.

Should I replace my water heater with a tankless?

Tankless water heaters can save you money on your energy bill in the long run, but they also require a greater initial financial investment upfront. Installation costs more, especially if you're installing your first tankless heater and require new gas lines and venting or a dedicated electrical circuit.

How many hours does it take to install a tankless water heater?

Installing a tankless water heater typically takes four to five hours, depending on the type of system and a household's needs. The installation process duration also depends on your location and which professionals are available when you need an installation.

Why not buy an electric tankless water heater?

Additional Installation Costs

Tankless water heaters are much more complex than traditional hot water tanks. As a result, they require professional installation. If you're switching from a hot water tank to a tankless unit, you will likely need your gas lines rerouted, as well as a larger gas supply line.

What size tankless water heater for family of 4?

Small households of two people need a tankless heater with a flow rate of 6 to 8 GPM, while a larger household of four people requires a flow rate of about 8 to 10 GPM. Remember to factor in temperature rise when deciding how big of a tankless water heater you need for your household.

Do you ever run out of hot water with a tankless water heater?

You can't run out of hot water with tankless water heaters – unless, of course, the power supply is off or goes out. However, a tankless water heater can have trouble keeping up with demand if too many things require hot water all at once.

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