There are three main factors that go into a water heater’s energy factor:
- Recovery efficiency: This describes how efficiently the water heater is able to transfer heat from its heat source to the water. ...
- Standby losses: In storage tank water heaters, energy is used to keep the water in the tank hot when it’s not in use. ...
- Cycling losses: Water loses heat as it travels through a water heater’s tank and pipes. ...
How much natural gas does a hot water heater use?
You can multiply the water heater’s thermal rating by the number of hours it operates in a day. Let us say a gas-powered water heater uses 20,000 BTUs per hour or about 0.2 therms per hour. If you use the water heater for four hours, you will need 0.8 therms. The price of natural gas in the US is $0.93 per therm, on average.
How does a water heater heat water so quickly?
how does a tankless water heater heat water so fast? Since the pipe material is cold, (unless you recently used hot water), it will absorb heat from the water as it flows to the sink until the pipe warms up to the temperature of the water. The colder the pipe the longer it takes to get hot water to the sink.
What is the thermal efficiency of a water heater?
In a conventional gas storage water heater, less than 50% of the fuel energy reaches the point of use. New efficient water heaters can help reduce this excess heat loss. The minimum efficiency of electric resistance storage water heaters is about 0.90 (depending on tank volume), and the best available are 0.95 EF.
How much does a 50 gallon electric hot water heater cost?
Electric Water Heaters An electric tank is less expensive to purchase and install than a gas tank, with a residential 50-gallon tank water heater priced around $500. However, the total cost of the monthly operation tends to be more expensive than that of a gas heater.
What is a good energy factor for a water heater?
As of September 1, 2010, a water heater needs to have an energy factor of 0.67 or higher in order to qualify for the Energy Star label. For gas condensing water heaters, the energy factor must be 0.8 or higher to qualify for the Energy Star label.
Where do I find the UEF on my water heater?
To find your water heater's UEF rating, go to the My Water Heater Information page and enter your model or serial number. If you need help finding them, there are instructions there as well. Once you enter your water heater's model number, you'll find the manuals and documentation for your heater.
What is the UEF on Rheem water heater?
Uniform Energy Factor (UEF): The newest measure of water heater overall efficiency. The higher the UEF value is, the more efficient the water heater.
What is the energy factor of a tankless water heater?
Tankless water heaters have a . 80 – . 99 energy factor. You will greatly reduce your heat loss when you convert to tankless, and use less fuel to heat the same volume of water.
How do I know if my water heater is energy efficient?
A water heater's energy efficiency is determined by the energy factor (EF), which is based on the amount of hot water produced per unit of fuel consumed over a typical day. The higher the energy factor, the more efficient the water heater.
Is energy factor same as thermal efficiency?
Generally, the EF number represents the thermal efficiency of the water heater as a percentage, since it is an average of the ratio of the theoretical heat required to raise the temperature of water drawn to the amount of energy actually consumed by the water heater.
Is a high efficiency water heater worth it?
High efficiency water heaters use 10 to 50 percent less energy than standard models, saving homeowners money on their utility bills. Actual energy savings from high efficiency water heaters depend on family size, heater location, and the size and placement of water pipes.
What is the difference between EF and UEF?
The Uniform Energy Factor (UEF) is the DOE's newly developed metric for communicating the energy efficiency of water heaters. Previously, you may have seen efficiency measured by Energy Factor (EF). UEF replaces this metric.
How is UEF measured?
UEF ratings are determined by assigning water heaters into one of four different categories of hot water usage and then evaluating their performance based on that usage. These categories are called bins. A water heater is assigned a UEF within its bin based upon its first hour rating.
Do tankless water heaters increase electric bill?
You can check if tankless water heaters are actually worth it and if they save you money here. Most households use less than 41 gallons of water per day. 24% – 34% is quite a lot of energy savings....Tankless Water Heater Electricity Usage By Hour.Wattage Of Electric Tankless HeaterCost Per Running Hour30 kW$3,9622 more rows
Do tankless water heaters use more electricity?
The Verdict: Tankless Water Heaters Are More Efficient The EPA estimates that a tankless water heater uses up to 34% less energy than a storage tank water heater if you use 41 gallons or less of hot water daily.
Which type of water heater is best?
While a conventional water heater typically lasts 10 or 15 years, a tankless can be expected to function reliably for 20 years or more. That longevity comes at a cost, however; tankless heaters sell for about double the price of conventional models.
What is a UEF number?
Uniform Energy Factor (UEF) rating A water heater's UEF rating is a measure of its energy efficiency, with higher numbers denoting more efficient units. The UEF calculation is based off of how much energy the water heater uses and how much energy is used to power the water heater itself.
What is the difference between EF and UEF?
The Uniform Energy Factor (UEF) is the DOE's newly developed metric for communicating the energy efficiency of water heaters. Previously, you may have seen efficiency measured by Energy Factor (EF). UEF replaces this metric.
How do I know if my water heater is FVIR?
A sensor inside the water heater will detect if it has ignited a flammable vapor from outside of the water heater and shut off the flow of gas to the burner and pilot light. How can I tell if my water heater is FVIR? Each manufacturer will have its own particular label for indicating if the model is FVIR.
Can you convert UEF to EF?
1 Answer. Since the UEF didn't exist back when those models were created, they both start with EF as the input. If you want to start with UEF, you could use the equations provided by RESNET to first convert UEF to EF: RESNET EF Calculator.
Are All Water Heaters Going Through This Change?
All residential water heaters sold in the U.S. must comply with this new approach. Commercial water heaters are subject to different rules and regu...
How Will This Affect The Water Heater’S Performance?
Our water heaters will remain as efficient and reliable as ever. Our water heater’s delivery capacity has not changed. The DOE’s new test procedure...
Will Water Heater Sizes Or Dimensions Change?
No. Our water heaters will still be available in the same sizes. The only thing that is changing is the way manufacturers communicate water heater...
WHAT IS ENERGY FACTOR FOR A WATER HEATER?
Energy Factor or EF is the measure of the energy efficiency of your water heater. It is calculated by dividing the amount of energy the water heater uses by the total energy that goes into running the water heater.
DOES A HIGHER WATER HEATER ENERGY FACTOR MEAN IT IS BETTER?
The energy factors will vary depending on the fuel source, design of the burner, tank insulation and other features. Electric water heaters with an energy efficiency between 0.67 or higher are qualified for the Energy Star label, while gas heaters with EF higher than 0.8 can get an Energy Star label. Gas water heaters typically have energy factors between 0.5 and 0.7, and for electric models, it is between 0.75 and 0.95.
ARE ALL WATER HEATERS GOING THROUGH THIS CHANGE?
All residential water heaters sold in the U.S. must comply with this new approach. Commercial water heaters are subject to different rules and regulations and are not changing at this time.
HOW WILL THIS AFFECT THE WATER HEATER’S PERFORMANCE?
Our water heaters will remain as efficient and reliable as ever. Our water heater’s delivery capacity has not changed. The DOE’s new test procedure and metric, however, will change the way that we talk about it. The amount of hot water the unit can provide in one hour of operation starting with a tank full of heated water is called First Hour Rating. In most cases, the First Hour Rating is a larger number under the new test procedures. This does not mean the water heater is providing more hot water than before. Do not substitute the new First Hour Ratings when selecting water heaters based on the requirements of the old First Hour Ratings.
WHAT IS UEF?
The Uniform Energy Factor (UEF) is the DOE’s newly developed metric for communicating the energy efficiency of water heaters. Previously, you may have seen efficiency measured by Energy Factor (EF). UEF replaces this metric.
What does higher UEF mean?
A higher UEF means a water heater is more energy efficient and will cost less to operate compared to other water heaters in the same bin. A water heater’s UEF can only be compared with water heaters within the same bin.
How is a water heater UEF determined?
UEF ratings are determined by assigning water heaters into one of four different categories of hot water usage and then evaluating their performance based on that usage. These categories are called bins. A water heater is assigned a UEF within its bin based upon its first hour rating. A higher UEF means a water heater is more energy efficient and will cost less to operate compared to other water heaters in the same bin. A water heater’s UEF can only be compared with water heaters within the same bin. For example a high bin water heater with a UEF of 0.95 does not perform exactly the same as that of a low bin water heater with a UEF of 0.95.
What does the Department of Energy do?
The Department of Energy implements energy conservation standards and test procedures for many appliances and equipment that we use every day , like water heaters, refrigerators, air conditioners, clothes dryers, lighting, and more.
What is the energy factor of a 40 gallon water heater?
A standard efficiency 40-gallon gas water heater typically has an Energy Factor of about .55, due to inefficiencies of combustion, a central flue carrying heat away with combustion exhaust, and a continuous gas pilot light, as well as standby losses through insulation and thermo-siphoning. We recommend gas water heaters with an Energy Factor of .62 or greater. This represents a 10 percent savings compared to a standard efficiency gas water heater. In addition to reducing standby losses with added insulation and anti-thermo-siphon device (heat traps), these improved efficiencies can be achieved for very little added cost by using electronic ignition instead of a pilot light, having automatic draft dampers, and reducing losses out the flue by recovering more of the heat first.
How many gallons of water can a gas water heater hold?
Gas storage water heaters with energy input ratings of 75,000 BTU/Hr. or less and with a storage capacity of not less than 20 gallons nor more than 100 gallons
What does EF mean in water heaters?
The energy factor (EF) indicates a water heater's overall energy efficiency based on the amount of hot water produced per unit of fuel consumed over a typical day. This includes the following: Water heaters listed in the energy factor ...
What is cycling loss?
Cycling losses – the loss of heat as the water circulates through a water heater tank, and/or inlet and outlet pipes.
What is recovery efficiency?
Recovery efficiency – how efficiently the heat from the energy source is transferred to the water
What is the foremost indicator when buying a new water heater?
When you start shopping for a replacement water heater, your foremost indicator in selecting a new water heater is the Energy Factor (EF).
What is the energy guide?
The Energy Guide can be a valuable tool. It compares the average yearly operating costs of different water heaters, using the same criteria for all models tested. It lets you see which one would probably cost you less to run. The higher the energy factor, the better.
What Energy Efficiency Rating Factors Have Changed?
The new UEF standard affects more than just the efficiency number itself. Adjustments in new DOE testing procedures now impact water heating performance stats associated with the amount of hot water produced in a real-world situation to the length of typical showers.
What is FHR rating?
First Hour Rating / First Hour Delivery (FHR/FHD) FHR, sometimes referred to as First-Hour Delivery (FHD), is the amount of hot water a water heater can provide in the first hour of operation. Updated testing procedures result in a more accurate representation of performance.
When did the EF rating change?
Beginning, June 12, 2017, EF ratings will be replaced with the new industry standard for measuring energy efficiency in water heaters called, Uniform Energy Factor (UEF). The new UEF rating method improves the industry’s ability to:
Do water heater ratings change?
You may notice new numbers associated with the water heaters you’re considering. The water heaters themselves haven’t changed, but the way we calculate the ratings and other facts and figures associated with them is different.
How to determine if a water heater is ENERGY STAR?
A water heater can be certified as ENERGY STAR by meeting Energy Factor (EF), Standby Loss, and/or Thermal Efficiency criteria or by meeting Uniform Energy Factor (UEF) criteria. Although these performance metrics are different, certification as ENERGY STAR by either method requires equivalent efficiency. Consumers should not directly compare EF values to UEF values.
What is the energy factor of a water heater?
Energy Factor (EF): An older measure of water heater overall efficiency that is being phased out due to new test methods for water heaters. The higher the EF value is, the more efficient the water heater. EF is determined by the Department of Energy’s test method outlined in the 10 CFR parts 200 to 499 edition revised as of January 1, 2014.
How many BTU per hour for a gas water heater?
Storage type units designed to heat and store water at a thermostatically controlled temperature, including: gas storage water heaters with a nominal input of 75,000 British thermal units (Btu) per hour or less, containing more than one gallon of water per 4,000 Btu per hour of input; electric heat pump water heaters with a maximum current rating of 24 amperes at an input voltage 250 volts or less. 1
What is a GPM?
Gallons per Minute (GPM): The amount of gallons per minute of hot water that can be supplied by an instantaneous water heater while maintaining a nominal temperature rise during steady state operation.
What is a gas fired storage unit?
Gas-fired storage units that are designed to deliver hot water at a temperature less than or equal to 180°F, with an input rate greater than 75,000 Btu/h but no greater than 105,000 Btu/h. These units are referred to as “Light Duty EPACT-covered” if they report thermal efficiency and standby loss as efficiency metrics and “Gas-fired Storage Residential-duty” if they report uniform energy factor as the efficiency metric.
What is solar water heater?
Solar Water Heaters. Solar water heaters include a collector and storage tank, and use the sun’s energy to heat water using one of the five basic types of solar water heating systems: forced circulation (includes both direct and indirect systems), integrated collector and storage, thermosiphon, self-pumped, or. photovoltaic (PV).
What is solar energy factor?
Solar Energy Factor (SEF): The energy delivered by the total system divided by the electrical or gas energy put into the system.
How long does a water heater last?
The typical lifespan of a traditional storage water heater is 10-15 years, though some water heaters may last longer with proper maintenance.
How much does it cost to install a heat trap on a water heater?
Install heat traps on your water heater tank to save $15-$30 a month on your water heating bill. Some new water heaters may already include heat traps, but older models may need a professional to install one. Insulate your hot water tank. Follow the manufacturer’s instructions or contact a professional to install insulation around your water heater ...
How much does it cost to fix a water heater leak?
Fix leaks as soon as you find them. A leak of just one drip per second can cost $1 per month.
What is the energy factor of a water heater?
The water heater energy factor (EF) indicates the water heater’s energy efficiency based on the amount of hot water it can produce per unit of fuel consumed on a typical day. This energy factor is useful for comparing the energy efficiency of traditional tank water heaters, tankless or “instantaneous” water heaters, and heat pump water heaters.
How to make a water heater more efficient?
How can I make my water heater more efficient? 1 Lower your water heater temperature to 120 degrees Fahrenheit. You can save between 3-5% on your water heating costs for every 10 degrees you lower the water heater’s temperature. 2 Fix leaks as soon as you find them. A leak of just one drip per second can cost $1 per month. The American Water Works Association estimates that at 60 drips per minute, you waste 8.64 gallons per day, 259 gallons per month, and just over 3,153 gallons per year! 3 Install heat traps on your water heater tank to save $15-$30 a month on your water heating bill. Some new water heaters may already include heat traps, but older models may need a professional to install one. 4 Insulate your hot water tank. Follow the manufacturer’s instructions or contact a professional to install insulation around your water heater storage tank.
How to determine first hour rating?
The First Hour Rating (FHR) in gallons, is determined by running a Department of Energy specified test with the outlet temperature of 125°F (+/- 5°F). A draw of three gallons per minute starts and then discontinues once the hot water outlet temperature drops 15°F. The water heater is then allowed to recover and the process continues repeatedly until one hour elapses. The sum of the amount of hot water drawn during the test is the First Hour Rating.
How long does it take for a water heater to recover?
The water heater is then allowed to recover and the process continues repeatedly until one hour elapses. The sum of the amount of hot water drawn during the test is the First Hour Rating.
Is the energy factor chart subject to change?
The Uniform Energy Factor Chart is subject to change without notice in accordance with our policy of continuous improvement.
What is the yellow energy label on a water heater?
When considering a water heater for your home, estimates of its energy efficiency and annual operating cost are shown on the yellow Energy Label. You can then compare costs with other more and/or less energy-efficient models. This will help you determine the dollar savings and payback period of investing in a more energy-efficient model, which will may have a higher purchase price.
What is cycling loss?
Cycling losses – the loss of heat as the water circulates through a water heater tank, and/or inlet and outlet pipes. The higher the energy factor, the more efficient the water heater. However, higher energy factor values don't always mean lower annual operating costs, especially when you compare fuel sources.
How many therms per day 365 days a year?
365 days a year X 0.4105 therms/day ÷ EF X Fuel Cost (therm) = estimated annual cost of operation
What is the energy factor used for?
Use the energy factor to determine the energy efficiency of a storage , tankless or demand-type water heater, or heat pump water heater.
What is recovery efficiency?
Recovery efficiency – how efficiently the heat from the energy source is transferred to the water
