If your home has a “closed” plumbing system, then yes, you'll need an expansion tank. You see, homes have either an open or a closed plumbing system. A closed plumbing system prevents water from flowing in the reverse direction (i.e., water won't flow back into city lines once it enters your home's pipes).
Although it is possible to use a water heater without an expansion tank, doing so is not advised. This is why:Water expands as it is heated. Your plumbing system's water pressure may drastically increase if you don't have an expansion tank since the hot water will have nowhere to go.
As plumbers know, the expansion tank equalizes pressure throughout the plumbing system by providing a space for hot water to flow into. Without an expansion tank, pressure would be distributed to the entire plumbing system, straining it and decreasing its lifespan.
The general rule of thumb for proper capacity of expansion is 12% of total coolant volume for draw down and 6% of the total volume for thermal expansion. Drawdown capacity is the amount of coolant that can be lost before air reaches the water pump and is introduced into the system.
A simple yet effective way to assess the condition of your expansion tank is by giving it a light tap. If the tank produces a hollow sound, it indicates that the tank is still in good working order.
An expansion tank is always highly recommended if you have a 'closed-loop system' caused by any kind of check valve or pressure regulating valve installed on your house's water supply line. A common illustration compares having high water pressure in your home to having high blood pressure.
You can tell if your thermal expansion tank is working by pushing the air valve (Schrader valve) on the bottom of the take and seeing whether or not air comes out. If air comes out, your expansion tank is working. If nothing or water comes out your tank is bad and needs to be replaced.
Typically a 2-gallon expansion tank works with a water heater with a 40 to 60-gallon capacity and a psi of 40 to 50. A 4.5-gallon expansion tank is needed for larger water heaters, such as ones that hold 80 gallons with 80 psi.
However, on average, an expansion tank can last 5 to 10 years or even longer if properly maintained and inspected regularly. It is recommended to check the expansion tank for signs of damage or wear, such as leaks or rust, at least once a year and replace it if necessary.
Water heaters with a capacity of up to 60 gallons should meet the following requirements: Water pressure less than 60 psi — 2-gallon expansion tank. Water pressure 60 psi or greater — 3.2-gallon expansion tank.
A water heater expansion tank costs $150 to $450 on average, with a national average of $325. The total cost depends on the size and type of tank. A water heater expansion tank costs an average of $325 to install, and most people pay between $150 and $450 for the task.
If your home has a Backflow Prevention Device, Pressure Reducing Valve (PRV), re- circulating pump with check valve, or anything else that prevents backflow of water installed, its plumbing system is considered "closed".
An expansion tank holds the steam and excess water created by heating, preventing it from over-pressurizing the system. A pressure tank acts as a reservoir, storing water to be pumped through the system at the correct pressure.
The role of an expansion tank is to regulate pressure within your hot water system, but, when an expansion tank fails, the air inside can block water from flowing. This occurrence is referred to as hydronic airlock.
FAQ: Expansion tank replacement
However, most tanks last between 5 and 10 years before needing to be replaced. If you're unsure whether your expansion tank needs to be replaced, it's best to consult a professional plumber.
Short answer? If your home has a “closed” plumbing system, then yes, you'll need an expansion tank.
An expansion tank is required on the supply line coming into the tank to reduce the tank stress which will shorten the tank's useful life. An alternative to the expansion tank is an approved pressure relief valve assembly. These devices are required on closed systems, which is public water.
This means if you have a 30-gallon hot water heater tank, you should get 21 gallons of hot water in the first hour. With a 50-gallon tank, you should get 35 gallons; and an 80-gallon tank will yield 56 gallons. This is because as hot water is being used, cold water continuously enters the tank.
Finally, testing your Thermal Expansion Tank is important and should be tested once a year when you flush your water heater. If your Thermal Expansion Tank is hanging from a pipe, you would push the Schrader Valve (air valve), located on the bottom of the tank, if the air is released then the tank is working properly.
Water will get inside of the system, of course, which means that you are going to need to drain expansion tank to make sure that the pressure that the tank absorbs is always at an optimum. This task shouldn't take very long, and should be done a couple of times a year by you or a professional.
If the pressure within the tank is too high or too low, it can cause the tank to fail. Should this happen, the rest of your plumbing system risks being damaged by high water pressure. You should check the pressure on your expansion tank at least once each year.
But expansion tanks can wear out. The average life of your tank can be anywhere between five and 10 years. You can extend the life of your expansion tank by making sure that your home's water pressure matches the air pressure in your expansion tank.
The cost of replacing thermal expansion tanks can vary, but usually falls somewhere between $250 and $500.