What are the differences between hot water heaters?

There are several types of hot water heaters, though most Texas homes are fitted with either a conventional hot water heater or a tankless option. There are also condensing water heaters (also termed condensing boilers) and heat pumps, but when considering a new water heater, the primary differences are whether you want a tank installed or not.

What is a conventional hot water heater?

Most homes get their warm water from a conventional hot water heater, which consists of the heater itself and a reservoir for holding water on standby. Hot water tanks come in a large variety of sizes, ranging up to 80 gallons, so they can meet the home’s warm water demands. In general, the smaller the tank, the more energy efficient it is, though the larger the tank, the more hot water you’ll have at the ready.

A conventional hot water heater works by taking in cold water from the bottom of the reservoir and holding it in storage while it is heated. This ensures the tank is always full and always heating more water. Heat supplied to the water can come from one of several sources, including:

  • An electrical heating element
  • Natural gas
  • Propane
  • Fuel oil

In Texas, most homes use natural gas or an electrical element to heat their water. Homes in rural areas may use propane, a heat pump or solar power to warm water.

There are several reasons why conventional hot water heaters are so widespread and popular among homeowners. Some of those reasons include:


Conventional hot water heaters are the most affordable on the market and provide many years of service, as long as they are properly maintained.


With regular maintenance, a conventional hot water heater will typically perform reliably for 10 years or more.

Easy installation

Experienced plumbers install conventional hot water heaters all the time, so there is a lot of familiarity with the process, and it’s rare that additional renovations or changes to the home are necessary. That keeps the cost of installation down as well.

Energy efficient models available

Conventional hot water heaters do suffer some heat losses (termed standby heat loss) while the warmed water sits in the tank. However, energy efficient models are designed with additional insulation that better traps heat, so your system runs more efficiently. Also, some conventional water heaters come with atmospheric sealing or fan assist for additional efficiency.

What is a tankless hot water heater?

Where a conventional hot water heater uses a reservoir tank, a tankless heater delivers hot water on demand.

Tankless hot water heaters are also called instantaneous heaters, because they rapidly warm up water as soon as it is needed. To do this, cold intake water is drawn in on demand. The water is pushed through an extended stretch of piping that’s surrounded by heating coils, so it comes in cold and leaves hot in a matter of moments. Like with a conventional hot water heater, a tankless water heater can use electricity or natural gas to supply heat.

Tankless heaters cost more upfront to purchase and install, but they come with a couple of big benefits, including:

1. Energy efficiency – Tankless heaters can be much more energy efficient than a conventional water heater, though it depends on how much hot water your family needs. Typically, you can expect to use 10-30 percent less energy with a tankless system, compared to a conventional heater. Greater savings are possible for homeowners that install multiple tankless systems, as this reduces how long the pilot lights run, which reduces waste.

2. Extended lifespan – Without a tank to maintain, a tankless hot water heater comes with fewer failure points than a conventional heater. Most tankless systems will last 20 years or more, and many components can be easily switched out when they are no longer viable, extending the system’s useful life even further.

3. Hot water on demand – As long as your family isn’t using too much hot water at once, a tankless system can keep the hot water coming as long as you need it. There’s no waiting on a tank to fill up with water, in other words.

To ensure there is enough water for every outlet, some homeowners opt for multiple tankless heaters. For example, one tankless system can provide hot water to high-demand appliances like a dishwasher, while another system ensures there is hot water for showers and sinks.

Whether you’re sticking with a conventional hot water heater or going tankless, it’s best to leave installation to the experts. Hot water heaters are cumbersome, potentially dangerous appliances that will experience early failure if not installed or maintained properly. Poor installation can also present an ongoing risk to the house, as pressure dysregulation can result in failure.

A licensed, insured and experienced plumber knows how to avoid the mistakes common to a botched installation. This ensures you’ll get many years of safe, reliable and efficient performance out of your hot water heater.

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