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For most folks, hot water heaters tend fall under the "if it ain't broke, don't worry about it" category.
Unfortunately, that's not a good idea. Although standard gas and electric water heaters might have a lifespan between 8 and 15 years, that's a broad and rather unhelpful range. Plus, there are many factors that conspire to shorten the life of a typical tank water heater.
Three common ones are:
And because a hot water tank doesn't come with a visible lifespan countdown, Home Depot suggests you look for the following hints of impending doom:
Regardless, if you've moved into a place and you don’t know how old the water heater is, or the water heater is over ten years old, it's time to seriously think about replacing it before a catastrophic failure. This gives you the time you need to do research, save, and not be stampeded into making a decision that may haunt you for years down the road.
Now, you might be asking, "How old is my water heater? Is there a way to figure it out? I don't want to jump the gun on this."
Probably. But it's going to require some sleuthing on your part. Tank labels may include an obvious manufacturing date. Or perhaps a helpful installer wrote the installation date using a marker on the side of the tank.
No luck? You must turn to serial numbers. Usually embedded within them are manufacturing date codes, but they are not easy to decipher. Here are two websites you should reference, as opposed to me trying to explain it here.
Or you can also call in a plumber and get his or her expert opinion on just how long a useful life your water heater has left.
It is no surprise that energy and utility costs are rising. What may be a surprise, though, is just how much water you use and how that equates to dollars spent.
And with rising costs, it is only going to get worse.
So, it makes a lot of sense (and cents) to find the most efficient water heater you can afford.
But, where to start?
Once upon a time, the choice was easy—tank style. Then you'd choose the fuel source and capacity, based primarily on what was there before. Efficiency was the furthest thing from anyone's mind.
Today, there are several hot water heater types you need to explore. The most widely used are:
We're going to focus on the first three as they are the most common. We'll provide links toward the end for the other two options.
Beyond the kind of water heater type, you also need to decide on the fuel source.
Most people go with the kind of fuel source that is already there. If you change from gas to electric and there's not a 220-volt outlet in sight, you will need to get that installed.
Remember, anything electric powered will not operate during a power failure. So, keep that in mind if that's a concern.
And what about capacity?
There are several ratings on water heater ENERGY GUIDE labels that didn't use to be there. All come into play when determining capacity, and ultimately, which water heater you choose. And most use abbreviations.
A key one is FHR or first hour rating. This simply means how many gallons of hot water you need during your peak hour of usage. For many people, it's when everyone is getting ready in the morning (hence the name), but your household may have a different schedule.
Also, FHR is measured with a 135° outlet temperature under EF measurements and 125° outlet temperature under UEF conditions. What are those? Keep reading.
EF means Energy Factor. Its latest iteration is called UEF or Uniform Energy Factor. With either term, the unit is ranked for how efficiently it turns energy into hot water. Generally, electric water heaters are between 0.75 and 0.95, while natural gas or propane ones are typically between 0.5 and 0.7.
But energy factor ratings don't consider the actual cost of the fuel. So, if natural gas or propane is cheaper in your area than electricity, the better value over the long run will be gas.
By the way, water heaters with an ENERGY STAR certification meet the high end of efficiency metrics. They use less energy than standard models, saving you money on your utility bills while helping protect the environment.
GPM means gallons per minute. This is especially important when it comes to tankless systems. The higher the number, the more hot water the unit can throughput all at once.
And Recovery Rate is an important number for tank style heaters. That's the number of gallons it can heat in an hour while the tank is refilling. If you use a lot of hot water for several consecutive hours, you'll want a higher recovery rate.
Understanding how much water your household uses at peak demand is critical.
If you underestimate this number, your water tank will be woefully undersized, and will provide lukewarm or cold water instead of hot. It might also wear out too quickly, trying to keep up with demand.
Overestimating means you're wasting energy heating and, in a tank style, storing more water than you really need.
So how do you determine your FHR?
The worksheet below is found on the energy.gov website. It's a great place to start and uses common averages for each water source.
Lowe's also has some estimates:
And Consumer Reports offers this easy guide that's relevant to tank-style heaters:
Courtesy Consumer Reports
If you would prefer to be more accurate in your GPM numbers to determine a more precise FHR, use the handy calculator found here. Turn on each hot water source with the typical hot/cold mix you would use. Then time how long it takes, in seconds, to fill a 1-gallon container. Fill in the seconds and hit calculate.
Or, if you're okay with basic math, take the seconds you measured and multiply by 60. That is the gallons per minute.
If all this math is giving you a headache and you know you want a tank style, Home Depot offers this advice:
Thanks to new standards and codes in play, today's tanks are larger than older ones of the same capacity. That's because, per Consumer Reports, water heaters under 55 gallons have a 4% boost in efficiency while those over 55 gallons are 25 to 50% more efficient, depending on the technology.
Bear in mind your FHR number too. You may not need as large of a tank as your current one, meaning a new, smaller capacity tank might well fit in your existing space.
But if your FHR indicates you need a tank that's bigger than your space, you might consider going tankless.
You now know your space limitations, your FHR and GPM, and you've decided on your fuel source—electricity, natural gas, propane, or heating fuel oil.
So, you're ready to do comparison shopping. Here are some other features to consider:
Also known as on demand hot water heaters, this style of hot water heater has been gaining in popularity in the US since it was introduced in the 1990s.
Here's a handy comparison chart between tank-style and tankless water heaters.
Tankless designs can also:
Sounds like a no-brainer, right?
Not so fast. There's more to consider.
We'll look at the overall pros and cons in the next section. But be aware that they do have GPM flow limits. So, if you have a very large household, you might need two units. For example, typical tankless units have a GPM of 2 to 5 gallons per minute. And they may not meet your FHR number.
Bobvila.com provides a suggestion when it comes to GPM and tankless units. "In general, a 1- or 2-bath home needs around 5 GPM. A large 3- or 4-bath home would need a 10 GPM unit."
But there's more to this than GPM.
Not only are FHR and GPM numbers critical to choosing the right size, so is a third one— Temperature Rise. It is the difference between the incoming water temperature and the desired output temperature. Since tankless water heaters heat water on the fly, the colder the incoming water, the more energy is required.
Temperature rise can be calculated using averages for groundwater as shown below from this map from ecodirect.com:
Or you can use a thermometer and measure the water temperature coming out of your cold-water tap.
So, if your incoming cold water is 67° and you want to heat it to 125° (the UEF standard), your temperature rise is 58. Most homes shoot for 115° to 120° to avoid scalding and to save energy.
Here in Oklahoma, tap temperatures can vary wildly, depending on the time of year. Since most people use more hot water in cold months, it's probably best to figure Temperature Rise based on winter tap-water temperatures. That way you'll know your unit is sized for the worst.
Once you are armed with these three critical measurements—FHR, GPM, and Temperature Rise—you're ready to start reading labels to determine what size you need. There is no one-size-fits-all when it comes to tankless. Because there are so many variables in play here, don't hesitate to consult your favorite plumber.
By the way, a tankless hot water heater is NOT a DIY installation.
According to energy.gov:
Additional advantages include:
In terms of additional features to look for (which may or may not be available depending on the fuel source):
And if you have a choice between installing an electric one or a gas one, know that gas units typically have twice the life of electric ones, but electric ones are more efficient and cheaper to install.
Tankless heaters require yearly maintenance. Skip this and you'll severely shorten the water heater's lifespan, defeating one of the primary reasons for getting one in the first place.
Probably the biggest threat to tankless heaters is hard water scale. If you live in an area with hard water (120 mg/L or more—you can buy a test kit at a home improvement store or online), you need to reduce limescale buildup. This is also true of tank-style heaters.
You can install either a whole house water softener (preferably a salt-less style if you are getting an electric tankless heater) or an inline filter cartridge that's designed to inhibit scale. Put a shutoff valve on each side of the cartridge for ease of replacement. Although vinegar can be added to the yearly flush to deal with scale, that works better for non-hard-water areas. If you have hard water and choose to skip treating the water, you'll need to do a flush at least twice a year with vinegar.
Sediment is a big issue too. If your tankless heater doesn't already have a screen filter, you should consider adding a sediment filter. This is especially true if you are on well water.
A heat pump water heater is a tank style with the tankless attribute of heating up only on demand. They are typically two to three times as efficient as a regular tank style. They use a heat pump as a supplemental heating energy. But they are taller and require more room to function properly.
According to efficiencymaine.com, heat pump water heaters:
ENERGY STAR also has thoughts about savings and the number of payback years for electric heat pump water heaters. So be sure to check it out.
These are a bit too complex for us to cover within the scope of this blog. So, for more information about solar water heaters, read this helpful page from energy.gov as well as this one from energysage.com.
And for tankless coil and indirect water heaters, check out this page from energy.gov.
Yes, usually so. But you need hunt for them, and they tend to change or expire every year.
Energystar.gov lists what ENERGY STAR equipment tax credits are available for primary residences. There are conditions:
There is also a rebate and special offers finder on the ENERGY STAR website. Simply plug in your zip code and then choose the product type to see what's currently available.
For state incentives, go to the US map located here. Just click on your state's shape.
And don't forget to check with your city and your local utility companies!
If you need help searching for the most efficient products, check out this site. You can research gas- and electric-fueled water heaters.
And for an overall review of water heating, visit energy.gov.
Here's an infographic from energy.gov with some great tips:
If you install lower-flow faucets and shower heads AFTER you figure out FHR and GPM, you'll need to recalculate those numbers.
So, be proactive about replacing your hot water heater. I was. That way I could plan and save for the replacement, rather than having to scramble in reaction to a catastrophic failure.
However, it's almost time for me to start shopping for a replacement. The gas hot water tank sits in the garage, snugly sharing cabinet space with my heat and air main unit. I'm torn between staying with a tank or going tankless. I'm pretty sure the allotted space will be too small to get another tank of the same capacity. Depending on what my research yields for FHR, UEF, GPM, and Temperature Rise, I'll make the final decision between a smaller capacity tank or a gas-fired tankless one. I am concerned about that auto low-flow cutoff associated with tankless systems. It would create all kinds of problems in super-cold weather when I must have both hot- and cold-water faucets drip. So, I'll need to do more research there too.
Hot water heater installs are best done by a pro. However, if you know you'll need a 1.5 ft. or 2 ft. long braided stainless steel water heater connector hose or a 4 ft. universal gas line connector kit for 1/2 in. lines to get the installation done, Certified Appliance Accessories has you covered. You can always buy them in advance for your plumber to use. You can purchase Certified Appliance Accessories online at Lowe's, Walmart, Amazon, and other ecommerce sites.
Once your new heater is installed, don't forget to put any manuals in your household appliance notebook. And most importantly, take a marker and write the installation date on the outside of the tank. Plus, write the FHR, GPM, and—if you went tankless—the Temperature Rise. Years down the line, you or the new owner of your home will be glad you did.
Disclaimer: This article is for informational and educational purposes only. Certified Appliance Accessories is not liable or responsible for any damages resulting from or related to your use of this information.