Question:
Dear Any Hour Services, Electrical, Plumbing, Heating & Air,
Recently, we had a plumber from another company come out to the house to look at our water heater and he noticed we didn’t have an expansion tank. He then strongly recommended we get one. Before I make any decisions, I thought I’d get a second opinion from you guys. What is an expansion tank and why would I need one?
– Sarah R.
Answer:
Great question! For starters, let’s talk about what an expansion tank is and then get into why many plumbers will recommend you get one if your water heater wasn’t initially installed with one.
Let’s start with your water heater. As water heats, it expands. But that expansion needs somewhere to go. It used to be that extra pressure in your plumbing system could just be sent back out to the city main line; however, with modern systems, there are now check valves installed by the city that prevent backflow into the municipal water supply. So, all of that pressure is now trapped in a closed system: your home’s plumbing.
The expansion and contraction of pressure can make the inside of your water heater bend and flex, which damages the vitreous glass liner on the inside of your water heater tank. This can cause cracks and leaks, which will eventually cause your tank to fail. It can also put undue pressure on the T&P (Temperature and Pressure) safety relief valve on your water heater, leading to failure over time. This pressure can also extend to appliances throughout your home, damaging the solenoid valve in your washing machine as well as the valves in your toilets, for example.
Essentially, an expansion tank is a device used to relieve pressure and hold displaced water as it expands when heated. It keeps your pumps, pipes, and other components from bursting or sustaining damage from pressure fluctuations. Their job is to maintain relative pressure throughout the system.
The expansion tank is divided into two parts. On the bottom half, it’s filled with compressed air and the other half is a rubber baffle or bladder. As the water expands, it pushes down on this bladder to relieve the pressure on the system. As the water cools, it pushes it back up and, in this way, equalizes the water pressure throughout the system.
If your water heater was installed without an expansion tank, it may be an older model tank. Most manufacturers now require that you have a water expansion tank installed with your water heater for the warranty to be valid because of its vital job of protecting the water heater.
It’s a very simple device that adds life and longevity to your appliances, particularly your water heater. If you don’t have one, talk to a plumber you trust about getting one installed and protecting your water heater, your plumbing, your appliances, and your home.
