Why bother with the label
Almost every question a plumber asks about a water heater is answered by a sticker you've probably never looked at. It's on the side of the tank, usually a foot or two below the top, and it holds the age, the size, the fuel, and a handful of numbers that decide what the replacement should be. If you can read it, you can get a sensible price over the phone in a couple of minutes. If you can't, the first visit is spent finding out.
Grab a flashlight and your phone. The label is often behind a pipe or in a dark corner, and a photo of it is worth more than a description.
Finding the age
The age is hidden in the serial number. There's no standard across makers, but a very common pattern is a letter for the month followed by two digits for the year. A is January, B is February, and so on through the alphabet. A serial that starts with C16 would be March 2016, and one that starts with L09 would be December 2009. Some makers start with the year and then the week of the year, which gives a number like 1608 for the eighth week of 2016.
If you can't make it out, don't guess. The maker's website will have a serial number decoder, and a plumber can usually read it on sight. Remember that the date shown is the date the tank was made, not installed. Most tanks go in within a year of being made, so it's a good guide.
Age matters because a tank typically lasts 8 to 12 years. The post on lifespan explains why, and the signs of failure tell you what to look for in an old one.
Finding the size
The capacity is printed in gallons, near the top of the label: 30, 40, 50, 65, 75, 80. For most Rowlett houses it will be a 40 or a 50. That tells you what the tank holds, though not how well it serves the house. What counts at the tap is how much hot water it can deliver in an hour, and for that, look for the first hour rating, which is on the yellow energy guide label if the tank still has it, or in the maker's specs online.
If you're thinking about changing the size, the post on sizing a water heater goes through the reasoning.
Gas label and electric label, side by side
The two types carry different numbers, because they need different things from the house.
- A gas label lists the fuel type, the input in BTUs an hour, the gas pressure range and the vent type. It also warns about clearances and the garage ignition height.
- An electric label lists the voltage, usually 240, the wattage of the upper and lower elements, and sometimes the amps. The wattage tells the plumber what size of breaker and wire the circuit needs.
- Both list the capacity, the working pressure and the model and serial number.
If you ever want to switch from one fuel to the other, those are the numbers that say what the house would have to supply. A swap from electric to gas needs a gas line and a vent, and one from gas to electric needs a 240-volt circuit and no vent. Neither is a casual change, and each is priced on the quote.
Finding the fuel
The fuel is stated clearly: natural gas, propane, or electric. It's also obvious from looking at the heater. A gas tank has a burner compartment at the bottom, a vent pipe going up from the top and a gas line coming in. An electric tank has no vent and one or two covered panels on the side where the elements and thermostats sit, and a thick cable with a conduit going in.
In Rowlett, gas comes from Atmos Energy and electricity is delivered by Oncor, so most houses can choose either. Whichever the old heater uses is the cheapest to keep, unless you're planning a bigger change, such as moving to a tankless or a hybrid unit.
Three made-up labels, decoded
These are examples to show the idea. Real serial numbers vary by maker.
- A serial that begins F14 is June 2014: F is the sixth letter, so the sixth month, and 14 is the year. A tank like that is now past the ten year mark.
- A serial that begins 1617 reads as week 16 of 2017, which is mid April. A tank like that is still in its nine-year window.
- A serial that begins K08 is October 2008, which makes the tank well past the usual life. It's overdue, and worth replacing on your own terms.
Some makers skip the letters, leave out vowels, or put the date in the middle of a long code. If your label doesn't fit any of these, a photo is the answer, and the maker's website often has a decoder that takes the serial.
The other numbers
There are several more things on the label that a plumber looks at:
- The model number, which tells the maker's line, the size and the vent type.
- For gas heaters, the input in BTUs an hour. A typical 40 or 50 gallon tank is somewhere around 30,000 to 40,000. It matters if you're thinking about tankless, because that one asks for far more.
- For electric heaters, the wattage of the elements and the voltage, usually 240 volts. It tells the plumber what the circuit has to carry.
- The maximum working pressure, usually 150 psi, which matches the relief valve.
- The clearance to combustibles and, on gas heaters, the vent and the gas pressure range.
- Warranty information, if the maker prints it.
You don't need to understand them all. Just photograph the label and let someone who does read it.
Mistakes people make with labels
The most common error is reading the capacity as how much hot water the heater can supply. It's the size of the tank. What you feel in the shower is the first hour rating and how fast the heater recovers.
Second is mixing up the made date and the install date. A tank can sit in a warehouse for a few months, so the date on the label is a little older than the install. It's close enough for planning, though not for a warranty claim, where the maker will want the install date and a receipt.
Third is assuming a heater that looks new inside is young. Insulation blankets, fresh paint and a tidy install can hide a tank that has been there a decade. The label doesn't lie. Read it.
What if the label is unreadable
Old labels fade, peel, get painted over, or are hidden by insulation blankets. Don't peel the blanket off to look. If you can't read the label, take a photo of the whole heater and tell us what you can: where it sits, whether it's gas or electric, and roughly how big it looks. A plumber can read the rest on site, and the fit check covers it. An unreadable label doesn't stop a quote. It just means the number is firmed up on arrival.
What to do with the numbers once you have them
Write the age, size, fuel and model on a card, or in your phone, along with the date. Then three useful things become easy.
First, you can call for prices knowing exactly what you have. Quotes from different plumbers are only comparable if each started from the same facts, and the label is the quickest way to give them the same ones.
Second, you can see where you are in the tank's life. A heater at eight or nine years is a prompt to start planning. One at four or five is a reason to start a flush routine and nothing more.
Third, you can register the warranty if it hasn't been done. Many makers want the registration within a set time of the install, and it's easy to forget. The model and serial number from the label are all it needs. If the heater was installed years ago and you never registered it, it's still worth checking what the maker's terms say, since some coverage depends on the original purchase and not on the registration.
What to say when you call
Three facts get the conversation going: the age, the size and the fuel. Add where the heater sits, and how many people and bathrooms are in the house. With those we can give an estimated range straight away, and say whether a like-for-like swap is the right plan or whether something else makes sense. The written quote comes after the heater has been seen, and nothing starts before you've read it.
That's the same process as on the replacement page. And if the tank is leaking as you read this, skip to the post on what to do when a water heater leaks.