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Water Heater Buying Guide: Tankless or Tank-Style


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Water heaters come in all different styles and sizes, and finding the one that best meets your household needs doesn't need to be difficult. Whether you're looking for a tankless or a tank-style water heater, or one that can service your entire household, or a point-of-use system that just provides hot water to a single sink, you'll need to do your homework.

In this article we'll cover the basic styles and provide you with resources for more indepth information to help you make an informed buying decision. With all the options available on the market today, the one that works best for your needs is often based on the size of your family, available storage space, and the fuel source available in your area.

Tank-Style Water Heaters

Tank-style water heaters are also commonly called storage tank water heaters because they store the hot water within a tank. They're the most common and versatile water heater on the market, and consist of an insulated tank that both heats and stores the water until it's needed. These systems are less energy efficient because the water needs to be stored and kept hot until it's used, which creates a tremendous amount of standby heat loss.

There are many options when it comes to fuel sources for tank-style water heaters. You can find models that are fueled by electricity, liquid propane (LP), natural gas, and even solar! And when it comes to price, a tank-style heater is far less expensive than a tankless water heaters, and in addition, you won't pay as much to have them installed. In fact, you can even do-it-yourself if you're into that sort of thing.

However, when it comes to service life, you can only expect about 8 to 10 years, where a tankless water heater is designed to last up to 20 years.

Whole house tank-style water heaters are available with tanks that range in size from 28 to over 100 gallons. Determining your household's hot water needs is called sizing. If sized correctly, you'll have a nice balance of not running out of hot water, while operating the most energy efficient unit to meet your hot water demands.

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How to Size a Tank-Style Water Heater

There are a number of methods used to determine your hot water needs, but probably the simplest is to use this general rule of thumb guideline. Of course, be sure to make adjustments to suit your individual needs.

Household Members

Recommended Tank Size

2 People

45 to 55 Gallons

3 People

55 to 65 Gallons

4 People

65 to 75 Gallons

5 People

75 to 85 Gallons

6 People

85 to 100 Gallons

7 People

100+ Gallons

When buying a tank-style water heater, one thing to consider is the recovery rate. The recovery rate is the amount of gallons of water the heater can heat in a single hour. The greater your household's demand for hot water, the higher the recovery rate you'll want to your water heater to be able to deliver.

> >  Read our Extensive Article on Sizing a Tank-Style Water Heater < <

Tankless Water Heaters

Tankless water heaters are also called on-demand water heaters because they heat water when there's a demand. These systems actually don't store hot water, but rather when a hot water tap is opened, the incoming cold water will run through a series of coils or heat exchangers.

One of the advantages of a tankless hot water heater is there isn't a tank to limit your use of hot water (provided you have selected the proper unit size). A tankless system can deliver an endless stream of hot water, so you'll never need to worry about taking too long of a shower.

They're also more energy-efficient than tank-style water heaters, which means that the majority of the energy they draw goes into heating the water (and not wasted to standby heat loss). Tankless water heaters are available in both nautral gas and liquid propane (LP) models, as well as electric.

Since tankless systems are mounted on a wall, they don't require any floor space. In addition, some are even designed to be installed outside, which frees up even more space.

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How to Size a Tankless Water Heater

Determining the correct size is critical since there's less margin for error. If you underestimate, your water heater won't be able to keep up with the demand for hot water . . . and there isn't a reserve tank to pick up the slack.

A tankless hot water heater is not limited by it's tank size, however, it is limited by its flow rate. There are a couple things that are important to consider when determining the proper sized appliance. 

  • The number of hot water points in use at one time during the peak usage hour.
  • The temperature rise which is determined by subtracting the temperature of the incoming water from the final hot water temperature (called a set point).

The majority of tankless water heaters can distribute at least 3.5 gallons of hot water each minute. This is typically sufficient for a home that doesn't need hot water in more than 2 points at the same time.

> > Check Out Our Tankless Water Heater Sizing Calculator < <

What to Read Next

Buying a water heater is a major purchase that will be with you for many years. We have plenty of articles that can help you make an informed buying decision, and give you the information you need to keep your new water heater running for years to come.

Here are just a few of the articles you might want to check out:

Tankless Water Heater Buyer's Guide

Tankless Water Heater: Gas vs Electric

Water Heater Buyer's Guide

Get the Best Price on Water Heater

Repair and Installation

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