The Hidden Dangers of DIY Water Heater Installation (And Why It Often Voids Your Warranty)

Johnny Perez
Jan 20
3 min read

It starts with a cold shower. Then, a trip to the big box store where you see a new water heater for $600.

You do the math: "If I hire a plumber, this might cost $1,500. If I watch a YouTube video, I can do it myself and save $900."

Stop right there.

We are all for saving money and learning new skills, but replacing a water heater is not the same as assembling an IKEA bookshelf. It sits at the dangerous intersection of Gas, Water, Carbon Monoxide, and High Pressure.

Before you wrestle that tank into your basement, you need to know what can go wrong—and why manufacturers often refuse to honor warranties for DIY installs.

1. The "Boom" Factor: Temperature & Pressure

A water heater isn't just a kettle; it’s a pressurized vessel.

Every tank is equipped with a T&P (Temperature and Pressure) Relief Valve. If the thermostat fails and the water gets too hot, the pressure builds up. If that relief valve is installed incorrectly—or if the discharge tube is blocked/undersized—your water heater literally becomes a bomb.

Mythbusters proved it: A water heater with a blocked valve can launch through the roof of a two-story house. Licensed plumbers know exactly how to pipe this safety feature to code. Do you?

2. The Silent Killer: Carbon Monoxide (CO)

If you have a gas water heater, you are dealing with combustion fumes. These fumes must be vented perfectly out of your home.

Common DIY Venting Mistakes:

Backdrafting: If the vent pipe isn't sloped correctly, or if the connection is loose, exhaust gases (including Carbon Monoxide) can spill back into your home instead of going up the chimney.
Wrong Material: Using the wrong type of tape or screws on the flue pipe can lead to leaks over time.

You cannot smell or see Carbon Monoxide, but it can be fatal. A professional ensures the draft is pulling correctly before they leave.

3. The Warranty Trap

This is the part the guy at the hardware store didn't tell you.

Read the fine print on that water heater box. Most major manufacturers (Rheem, Bradford White, A.O. Smith) have a clause that states the warranty is valid only if installed by a licensed professional.

If you install it yourself and the tank leaks next year, flooding your finished basement, the manufacturer may ask for the license number of the installer. If you can't provide it, your warranty is void. You are on the hook for the new tank and the water damage.

4. Code Violations & Selling Your Home

Building codes change constantly.

Does your area require a thermal expansion tank?
Do you need seismic strapping (earthquake straps)?
Is an electrical disconnect required within sight of the unit?

If you install it yourself and miss these codes, a home inspector will flag it when you try to sell your house. You will likely be forced to pay a plumber to come out and "re-do" your work properly before the sale can close.

The Financial Reality: Why People DIY (And the Better Alternative)

We know why people try to install these themselves: Cash Flow.

Water heaters usually break unexpectedly. Dropping $1,500 to $2,500 on a Tuesday afternoon is painful. But risking your family’s safety or your home’s value to save the labor cost isn't the answer.

If money is tight, the solution isn't DIY—it’s Financing.

Spreading the cost of a professional installation over 12 or 24 months costs a few dollars a coffee per month. In exchange, you get:

Safety: A certified, code-compliant install.
Protection: A valid manufacturer's warranty.
Peace of Mind: No waking up to a flooded basement.

The Bottom Line

Some things are perfect for DIY (painting, landscaping, changing a faucet). Gas appliances are not. Respect the trade, respect the danger, and hire a pro.

Need Hot Water Fast?

Option 1: Get it Installed Today (Safely) Connect with a Licensed Plumber who knows local codes and safety standards. > Find a Verified Plumber Here

Option 2: Don't drain your bank account. Apply for instant financing and pay for your new water heater over time. > See Your Payment Options