Home Service Blog Articles by Tiger®

What is a Water Heater’s Energy Factor?

Published: February 12, 2015

When it comes time to choose a new water heater in your Collinsville area home, you’ll have an small_8553602120array of different types of units to choose from. Although a water heater’s energy factor won’t be the only deciding factor when you’re choosing a new unit, it’s certainly one of the most important things you’ll want to consider.

What is a water heater’s energy factor?

The energy factor (EF) of a water heater is a number that describes a unit’s energy-efficiency. The higher the EF of a given water heater, the more efficient the unit is. Every water heater is assigned an EF, and you can use it as one of the deciding factors when choosing which unit is right for your home.

How is a water heater’s energy factor calculated?

There are three main factors that go into a water heater’s energy factor:

  1. Recovery efficiency: This describes how efficiently the water heater is able to transfer heat from its heat source to the water. This is similar to a furnace’s AFUE rating in that it describes how effectively it is able to put the energy it consumes to good use.
  2. Standby losses: In storage tank water heaters, energy is used to keep the water in the tank hot when it’s not in use. The amount of energy that’s needed to do this (measured per hour) is known as standby loss.
  3. Cycling losses: Water loses heat as it travels through a water heater’s tank and pipes. The amount of heat that’s lost while this occurs is known as cycling loss.

What is a good energy factor rating for a water heater?

When you’re comparing the energy factor of different water heaters, it’s important to also keep each unit’s fuel-source in mind. Electric water heaters, for example, can have much higher EF ratings than gas water heaters, but gas is a much less expensive fuel source and is almost always going to cost less to operate. So when you’re comparing energy factors, it’s best to compare the EF’s of units that use the same fuel source.

In order to qualify for the Energy Star label, gas storage water heaters must have an EF of at least 0.67; gas condensing water heaters must have an EF of at least 0.8; heat pump water heaters must have an EF of at least 2.0; gas tankless water heaters must have an EF of at least 0.82; and solar water heaters must have an EF of at least 0.5.

If you have any questions about a water heater’s energy factor, or if you’d like a plumbing system serviced or installed in your home, contact Tiger, your Collinsville plumbing, heating and air conditioning company.

photo credit: ww_whist via photopin cc

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