Water Heater Installation: Things Homeowners Overlook (And How to Fix It)

A water heater is one of those home appliances you don’t think about—until there’s a problem. You expect hot water on demand, but what happens when a poor installation leads to inefficiency, leaks, or dangerous situations?

Many homeowners make critical mistakes during installation. These aren’t minor issues; they can shorten the lifespan of your unit, spike energy bills, and even void your warranty.

Let’s look at the most overlooked details during water heater installation—and how to fix them before they cost you.

1. Choosing the Wrong Size Unit

Bigger isn’t always better. Neither is smaller. A wrong-sized water heater leads to one of two problems:

● Too Small? You’ll run out of hot water fast, especially during peak usage.

● Too Big? You’ll waste energy keeping unused water hot.

How to Fix It:

● Consider household size: A 40-gallon tank suits 2-3 people, while a 50- to 80-gallon works for larger families.

● If going tankless, ensure the flow rate meets demand.

● Consult a licensed plumber for sizing recommendations.

2. Ignoring Local Building Codes

Skipping permit requirements or ignoring safety regulations can lead to fines, insurance issues, or a failed home inspection. What homeowners overlook:

● Gas water heaters require proper venting to prevent carbon monoxide buildup.

● Electric units need correct wiring and breaker sizing to prevent overheating.

● Many cities require seismic straps, drain pans, and shutoff valves for safety.

How to Fix It:

● Check local codes before installation.

● Hire a licensed professional who understands compliance.

● Don’t DIY if unsure—code violations can be expensive.

3. Poor Venting (For Gas Water Heaters)

Gas water heaters produce combustion gases that must be safely vented outside. Improper venting leads to carbon monoxide buildup, back-drafting, and fire hazards. What goes wrong?

● Flue pipes installed at the wrong angle cause gases to linger.

● Vent pipes that aren’t properly sealed let deadly fumes leak into the home.

● Indoor placement without adequate ventilation increases carbon monoxide risks.

How to Fix It:

● Ensure proper pipe slope (rising at least ¼ inch per foot).

● Use sealed venting systems to prevent gas leaks.

● Install carbon monoxide detectors near your water heater.

4. Skipping the Expansion Tank

A thermal expansion tank absorbs extra pressure when water heats up. Without it, your water heater faces excessive stress, leading to leaks or a burst tank. Why it’s overlooked:

● Many older homes didn’t require them, but new plumbing codes do.

● Some plumbers cut corners to save time or money.

● Homeowners don’t realize high water pressure worsens the problem.

How to Fix It:

● Check your home's water pressure. If it’s above 80 psi, an expansion tank is a must.

● Install an expansion tank if your home has a closed plumbing system.

● Ask your plumber about local code requirements.

5. Forgetting to Drain Sediment Buildup

Water heaters collect mineral deposits over time, especially in areas with hard water. If ignored, sediment:

● Reduces efficiency, making your heater work harder.

● Causes rumbling noises and overheating.

● Leads to premature tank failure.

How to Fix It:

● Drain a few gallons every six months to remove sediment.

● Use a water softener if your area has hard water.

● Consider a tankless water heater to eliminate sediment issues.

Final Thoughts

Water heater installation isn’t just about hooking up a tank—it’s about safety, efficiency, and long-term reliability. Overlooking key details leads to higher costs, dangerous conditions, and unnecessary headaches.

By choosing the right size, ensuring proper venting, following local codes, and keeping up with maintenance, you’ll get the most out of your system—and avoid costly mistakes.

A little attention now prevents big problems later.