Water Heater Expansion Tanks: Why Goodyear Building Codes Require Them
If you’ve recently had a water heater installed or inspected in Goodyear, you might have noticed a small tank sitting on top of or next to it. That’s a thermal expansion tank. In the past, these weren’t always required, but today, they are a strict requirement under Goodyear building codes for closed-loop water systems. As a Goodyear plumber, we see a lot of confusion from homeowners about what these tanks actually do and why the city mandates them. Let’s break down the physics simply and explain why this small addition is so important for your home’s plumbing.
The Simple Physics of Water Heating
To understand why an expansion tank is necessary, we need to look at what happens when water heats up. When cold water enters your water heater and the burner or elements kick on, the water absorbs that heat and expands. It’s basic physics—thermal expansion. In a standard 50-gallon water heater, the water volume can expand by nearly half a gallon as it heats up from room temperature to 120°F.
In older plumbing systems, this extra volume wasn’t a big deal. The expanding water would simply push back out into the city water main. However, modern systems are what we call “closed-loop.” To prevent contaminated water from flowing back into the public water supply, cities install backflow preventers or check valves at the meter. This creates a closed system in your home. Now, when that water heats up and expands, it has nowhere to go. The pressure inside your pipes and water heater begins to spike.
Why Goodyear Building Codes Require Expansion Tanks
Because that pressure has nowhere to go in a closed-loop system, it puts tremendous stress on your plumbing. It can damage fixtures, wear out seals, and even shorten the lifespan of your water heater. The City of Goodyear building department requires thermal expansion tanks to handle this exact issue. These codes are in place to protect your property and ensure the safety and longevity of your plumbing system.
The expansion tank acts as a shock absorber. Inside the tank is a rubber bladder filled with compressed air. As the water in your heater expands and the pressure rises, it pushes against the bladder, compressing the air and giving the extra water volume a safe place to go. Once you open a faucet and relieve the pressure, the air pushes the water back into the system. It’s a simple but incredibly effective solution to a potentially destructive problem.
Signs Your System is Failing Without One
If your home has a closed-loop system without a functioning expansion tank, you’ll likely start noticing signs of excess pressure. One of the most common indicators is a dripping Temperature and Pressure (T&P) relief valve on your water heater. This valve is designed to open and release water if the pressure gets dangerously high. If it’s constantly weeping or dripping, it’s doing its job, but it’s a clear sign that thermal expansion is over-pressurizing your system.
Another sign is “water hammer.” If you hear loud banging or clunking noises in your pipes when the water heater is running or when you quickly shut off a faucet, that’s often due to high pressure. Over time, this constant stress can lead to premature leaks in your water heater tank or blown out washers in your faucets and toilets. We’ve seen many water heaters in Goodyear fail years before their time simply because they lacked an expansion tank.
Installation and Typical Costs
Installing an expansion tank isn’t a massive project, but it does need to be done correctly to meet code and function properly. The tank must be sized correctly based on the capacity of your water heater and the incoming water pressure. It’s typically installed on the cold water supply line right above the water heater. The air pressure inside the tank also needs to be matched to your home’s incoming water pressure before installation.
In terms of cost, adding an expansion tank during a new water heater installation is relatively inexpensive. The tank itself usually costs between $50 and $100, plus a little extra for the fittings and labor. If you need one retrofitted to an existing system, the cost will be slightly higher due to the extra labor involved in cutting and modifying the existing pipes. However, compared to the cost of replacing a prematurely failed water heater or repairing water damage from a burst pipe, it’s a very smart investment.
Protecting Your Home’s Plumbing
Goodyear’s hard water and high summer temperatures already put enough stress on your plumbing. You don’t need thermal expansion adding to the problem. If you’re unsure whether your home has a closed-loop system or if your current expansion tank is functioning properly, it’s worth having a professional take a look. We provide comprehensive plumbing services Goodyear Arizona residents can rely on to keep their systems safe and up to code.
If you need an inspection, a new water heater, or just have questions about your home’s plumbing pressure, reach out to AZ Home Services Group. Our technicians are ready to help you protect your home and ensure your plumbing runs smoothly for years to come.
