You just got a new water heater installed—great news. But the job doesn’t stop the moment the last pipe is tightened. What you do in the hours and days after installation can make a big difference in how safely and efficiently your unit runs, and how long it actually lasts.
This guide covers everything you need to know about what to do after installing a new water heater. From running your first safety check to setting the right temperature, registering your warranty, and locking in a maintenance routine, we’ve got you covered. Whether you’re a homeowner taking ownership of a recent installation or a plumber finishing up a job, these steps will help you get the most out of a brand-new unit from day one.
Start With a Safety Inspection and Leak Check
Before anything else, do a full visual inspection of the unit and all connections. Look at the inlet and outlet pipes, the pressure relief valve, the gas line or electrical connections (depending on your unit type), and the base of the tank.
Even a small drip can signal a loose fitting or a seal that didn’t seat properly. Run your hand along each connection to feel for moisture, and keep an eye out for any water pooling around the base. Gas units require an extra step—use a gas leak detector or apply soapy water to the gas fittings and check for bubbles.
If you spot anything unusual, shut off the water supply and don’t power on the unit until the issue is resolved. Getting this right from the start protects both the unit and the people in the building.
Set the Right Temperature
The U.S. Department of Energy recommends setting your water heater to 120°F (49°C) for most households. This temperature is hot enough to be effective while reducing the risk of scalding and limiting energy consumption.
Some units ship with the thermostat set higher than needed—around 140°F. Dialing it back to 120°F typically reduces standby heat loss and can lower water heating costs by 4–22%, according to the DOE. For homes with immunocompromised residents or dishwashers that don’t have a booster heater, bumping up to 140°F may be appropriate.
For gas water heaters, the thermostat is usually located on the front of the unit. Electric units often have thermostats behind access panels on the side. Adjust carefully, and allow a few hours for the water to reach the new set temperature before testing at the tap.
Test the Pressure Relief Valve and Flush the Lines
The temperature and pressure (T&P) relief valve is a critical safety feature. It opens automatically if pressure or temperature inside the tank exceeds safe levels. After installation, testing it should be a non-negotiable step.
To test it, lift or press the lever briefly and let it snap back. You should see a small burst of water discharge from the valve’s pipe. If nothing comes out, or if the valve continues to drip after the test, it may need to be replaced. This is one of those checks that’s easy to skip and costly to ignore.
Next, flush the lines. Air pockets can form during installation, and sediment or debris from the pipes can work its way into the system. Open a few hot water taps throughout the building and let the water run for a few minutes. This clears out any trapped air, discolored water, or debris before the heater enters regular operation. Expect some sputtering at first—that’s completely normal.
Register Your Manufacturer Warranty
This step takes about five minutes and is almost always forgotten. Registering your water heater’s warranty with the manufacturer ensures you’re covered if anything goes wrong down the line. Most warranties on quality units run anywhere from 6 to 12 years, but coverage only kicks in if the product is properly registered.
Keep the model number, serial number, and installation date somewhere accessible. A photo on your phone or a note in a job folder works fine. Some manufacturers require registration within 30 days of installation, so don’t sit on this one.
Set Up a Regular Maintenance Schedule
A new water heater is an investment. Protecting that investment means building in regular maintenance from the start—not after something goes wrong.
Here’s a simple maintenance checklist to follow:
- Every 6 months: Test the T&P relief valve and check the anode rod condition
- Annually: Flush the tank to remove sediment buildup, which reduces efficiency and can shorten tank life
- Every 3–5 years: Inspect or replace the anode rod (this sacrificial rod prevents corrosion inside the tank)
- As needed: Check all connections, fittings, and the expansion tank (if installed)
Sediment buildup is one of the most common reasons water heaters underperform or fail early. It’s especially common in hard-water areas across Arizona, Nevada, and Texas. A consistent flush schedule keeps things running clean and efficient.
Troubleshooting Common Post-Installation Issues
Even with a flawless installation, a few hiccups are normal in the first days of operation. Here are the most common ones and what to do about them:
Discolored or rusty water: This usually clears up after flushing the lines. If it persists, it could indicate a failing anode rod or corrosion inside the tank.
Water that isn’t hot enough: Check that the thermostat is set correctly and give the unit adequate time to heat a full tank. On electric units, one of the two heating elements may not be functioning properly.
Popping or rumbling sounds: This is almost always sediment at the bottom of the tank. Flush the tank and the sounds should reduce. If not, the element may be coated in buildup.
Water dripping from the T&P valve: A small amount after testing is expected. Continued dripping suggests the valve is faulty or that pressure inside the tank is too high—both require attention.
Pilot light keeps going out (gas units): Check for drafts near the unit, inspect the thermocouple, and ensure the gas supply is consistent.
If an issue persists after these checks, it’s worth calling in a licensed plumber rather than letting the problem sit.
Tips for Maximizing Energy Savings
A new water heater is already going to be more efficient than an older unit, but a few smart habits can push those savings further.
Insulate the pipes: Foam pipe insulation on the first few feet of hot and cold water pipes connected to the heater helps retain heat and reduces the distance heat needs to travel.
Use a timer (electric units): Programmable timers let you set the heater to operate only during peak usage hours, reducing standby energy consumption overnight or during long absences.
Install heat traps: Many modern units come with heat traps built in. If yours doesn’t, ask your plumber about adding them to the inlet and outlet pipes—they prevent hot water from naturally circulating out of the tank.
Check for proper sizing: An oversized unit wastes energy heating more water than you need. If your new heater was correctly sized for the building’s demand, you’re already ahead.
Lower the temperature slightly: As mentioned earlier, dropping from 140°F to 120°F can yield meaningful energy savings without impacting daily use.
Why Van Marcke Plumbing Supply Is the Right Partner for the Job
Having the right parts on hand makes everything easier—whether you’re doing the install yourself or managing a crew across multiple jobsites. Van Marcke Plumbing Supply carries over 6,000 brand-name products across locations in Arizona, Nevada, and Texas, including water heaters, anode rods, expansion tanks, pressure relief valves, and all the fittings and accessories you need.
Need to order after hours? PlumbersOnly.com gives you 24/7 access to Van Marcke’s full product catalog, so you can place orders whenever the job demands it. With timely delivery, competitive pricing, and a loyalty rewards program that puts points back in your pocket, Van Marcke makes it easy to stay stocked and keep projects moving.
When quality and reliability matter—and on water heater installations, they always do—Van Marcke is your local supply partner.
Make the Most of Your New Unit
Getting a new water heater is the first step. Following through with the right post-installation steps is what turns a good installation into a long-lasting, efficient one. Run your safety checks, set your temperature, test that relief valve, register the warranty, and build maintenance into your calendar.
The small time investment up front pays off in fewer repairs, lower energy bills, and a unit that goes the distance. And when you need parts, supplies, or your next water heater, Van Marcke Plumbing Supply has everything you need—online or in-store, whenever you need it.