Pros and Cons of Tankless Water Heaters: A Comprehensive Guide

Last updated on January 15, 2024

Tankless water heaters, also known as on-demand or instantaneous water heaters, have become an increasingly popular option for domestic hot water over the past few decades.

As the name suggests, tankless water heaters heat water directly without the use of a storage tank. Rather than keeping a reservoir of hot water ready at all times, they utilize high-powered heating elements that quickly heat water as it flows through the unit.

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This unique functionality provides both advantages and disadvantages compared to conventional storage tank water heaters. By considering the pros and cons of tankless systems, homeowners can decide if such a system meets their needs.

This guide breaks down the key benefits and drawbacks.

Pros of a tankless water heater

1. Energy Efficiency

One of the main attractions of tankless water heaters is their exceptional energy efficiency. Because they only heat water on demand, they avoid the standby energy losses associated with storage tank heaters.

Studies show tankless models being 24-34% more energy efficient on average. This equates to significant energy savings over time.

2. Space-Saving Design

Tankless water heaters are far more compact than traditional tank heaters. They take up much smaller indoor and outdoor space compared to bulky tank units. Many models are designed for convenient wall-mount installations. For small living spaces, the design can be hugely beneficial.

3. Continuous Hot Water Supply

Homes with storage tank systems can often run out of hot water during high demand. Since tankless heaters provide on-demand hot water, they eliminate problems with depleted hot water availability. The unlimited supply is ideal for larger homes with extensive needs.

4. Longer Lifespan

While storage tank heaters typically last between 8-12 years, tankless units have lifespans of 20 years or longer. Their average working life is nearly double that of tank heaters.

With proper maintenance, some models function effectively for up to 30 years before needing replacement. The enhanced durability leads to higher long-term value.

5. Reduced Risk of Water Damage

Because tankless heaters don’t store any water internally, they carry no risk of internal corrosion and leakage.

On the contrary, for tank storage heaters, tank corrosion is common over time, often resulting in cracks and water damage. Tankless models provide greater installation flexibility and prevent costly repairs by removing this leakage risk.

6. Customizable Temperature Settings

Tankless water heaters give users precise control over output water temperature. Temperature can be easily adjusted via digital controls or smartphone apps.

This allows households to customize temperatures for specific needs – from high-temperature sanitization to kid-safe showering. Temperature customization promotes both safety and convenience.

7. Lower Operating Costs

Tankless water heaters’ exceptional energy efficiency and durability translate into lower monthly costs for homeowners.

Reduced energy consumption cuts electricity bills substantially compared to conventional models. And with a working life span of up to 30 years, replacement costs are minimized as well and long-term savings add up tremendously.

Cons of a tankless water heater

1. Higher Initial Cost

While tankless heaters save money in the long term, their initial purchase price is significantly higher than that of traditional water heaters.

Unit prices range from $600 up to $3,500 depending on size, flow rate, and features. Installation also tends to be more labor-intensive and complex, resulting in higher total costs. The steep upfront investment deters many homeowners.

2. Limited Flow Rate

A common downside of tankless systems is constrained flow rate, particularly with basic whole-home models. While storage tanks easily support simultaneous use across multiple fixtures, tankless heaters have limited heating capacity.

Basic units may provide only 3-5 gallons per minute (GPM) – enough for just a couple taps at once. Upgraded models are needed to power whole-home demand.

3. Cold Water Sandwich Effect

Occasionally tankless heaters exhibit a phenomenon known as the sandwich effect. This refers to a blast of cold water between cycles of hot water delivery. It’s caused by small amounts of cooler water left in internal pipes being pushed out by newly heated water.

4. Not Ideal for All Climates

Homes in extremely cold climates are often poor candidates for tankless installation. Heaters must fire at full capacity to raise near-freezing inlet water to suitable temperatures. As a result, output flow rates suffer drastically in cold weather.

Additionally, tankless heaters are vulnerable to freezing without sufficient indoor buffering from frigid outdoor air.

5. Maintenance Requirements

While tankless heaters last longer, they require more routine maintenance over their lifespan. Annual inspections and water flushing are recommended to maintain efficiency and prevent operational problems.

They will occasionally require professional servicing at added costs. If ignored, mineral buildup can accelerate wear on internal components as well.

6. Complex Installation

Switching to a tankless system often necessitates extensive modifications to existing plumbing and gas lines.

New dedicated electrical circuits may be required as well. And without a sufficient flow rate to start, units won’t ignite. All these factors complicate DIY installations. Tankless setups usually call for professional expertise – tacking on thousands more in labor expenses.

*Pros and Cons of Tankless Water Heaters infographic*

Flowing Forward: A Final Verdict on Tankless Water Heaters Advantages and Disadvantages

Tankless water heaters offer benefits like endless hot water supply, potential energy savings, compact size, and enhanced durability. These advantages of tankless water heaters may justify the steep initial investment required and occasional quirks.

But tankless models also have distinct drawbacks ranging from high costs to climate suitability issues, so there is no universal “best” option.

By weighing the pros and cons, each household can determine if transitioning from a storage tank heater to an on-demand tankless unit meets their requirements and needs. With sound information, homeowners can choose the hot water solution that fits their lifestyle and budget.