Blog, Water Heater

Tank or Tankless Water Heater: Which is Best?

The most common type is a tank unit. But a tankless water heater system does have some advantages. If yours needs to be replaced, or if you are considering an upgrade, here are some things you’ll need to know before you decide what to buy.

Tank Hot Water Heater

This system has a holding tank that is usually sized based on the number of people in your household.

Household Size               Gallon Capacity

2 or less                            30 gal. or less

2-4                                     40 gal.

3-5                                     50 gal.

5 or more                         60 gal. or more

If you frequently have guests staying over, if you like to shower while your spouse is giving the kids a bath, or you have a large whirlpool bathtub, you may want to bump up to the next size tank. To maintain efficiency and extend its life, you need to flush it out about every 6-12 months to get rid of mineral and calcium deposits. It’s an easy process and involves only a garden hose, but there is a sequence to follow to avoid any damage. If you are uncertain or want to make sure you don’t make the situation worse, a professional plumber will do it for you.

Tankless Water Heaters

Instead of a tank, tankless water heaters have a heat exchanger that the water travels through to be heated. In theory, there is no limit to the amount of hot water available with a tankless unit. But a tankless water heater must also be sized according to your usage needs. If you pull too much water through too fast, the water may be cool. This might happen if you change your shower head to a high-capacity massage one or remodel your shower to one with multiple heads at different levels. If you install a tankless unit of higher capacity than you really need, the heater unit may cycle on and off resulting in inconsistent temperature for your shower.

Cost Savings

A tankless water heater heats “on demand.” As a result it has a cost savings by not heating the water all the time, just to keep it hot. However, tankless water heaters typically cost several times more than a tank unit. A tankless water heater also requires a more robust energy source. People are often surprised to find their gas or electric service is not sized to be able to handle the extra capacity needed. These extra upgrade costs add to your initial investment costs. You need to determine if the savings will offset the higher initial cost of a tankless water heater.

Instant Hot Water

There is a myth that a tankless water heater provides instant hot water. It will if it is installed directly at the faucet. Otherwise, you still have cold water between the hot water heater and your faucet that must come out before you feel hot water. So, there is really no difference in “time to hot” between a tank and tankless water heater. The best way for either system to have nearly instant hot water at the faucet is to get a hot water circulation system.


A tankless hot water heater will typically last longer than a tank system, but a tankless also requires periodic flushing. This maintenance is more critical than for a tank system and requires a flush kit (typically $150 to $250) which is a bit more involved such that many people just have their plumber do it.  As a result, also eats into the energy savings you would expect from a tankless water heater system.

Let’s Review

Tank water heater advantages:

  • Lower initial cost
  • Consistent water temperature
  • Can better handle multiple users
  • Easy maintenance
  • Standard home electric or gas services can handle it

Tank water heater disadvantages:

  • Higher energy costs
  • Shorter life
  • Takes up more space
  • If you run out of hot water, it takes several minutes to recover

Tankless water heater advantages:

  • Lower operating costs
  • Longer life
  • Takes up less space
  • Can provide nearly limitless hot water, within its water heating flow rate

Tankless water heater disadvantages:

  • Higher initial cost
  • May require gas or electric service upgrade in your home
  • May require a water softener for the warranty to be valid
  • Water can run cool if exceeding heating flow rate
  • Inconsistent water temperature if the unit is not properly sized
  • Does not handle multiple hot water users well
  • More frequent and expensive periodic flushing

Practical applications for a tankless water heater include a small house with two people, an addition to a home where it is far from the tank water heater, a horse barn or detached workshop where hot water is not needed every day.

Choosing a Hot Water Heater

The overwhelming choice by most owners is a tank system. Therefore, unless you have a special situation, instead of spending extra money on a tankless water heater, you may be happier spending it on adding hot water circulation to a tank system and enjoy near instant hot water to all your faucets.

With nearly two decades of experience, Cole’s Plumbing is professionally qualified to install and service your home or business tank or tankless water heaters. We have the right equipment, tools, and experience to do the job right – at an affordable price. Please call/text us at (972) 210-9033 or complete the Get an Estimate form to discuss how we can help you safely get the most out of your hot water heater.

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