Going from a tank to a tankless water heater is one of the most effective ways to lower your utility bills. The switch also frees up more space and ensures a consistent hot water supply, as the water is heated on an as-needed basis. It costs between $5,400 and $7,400 to install a new tankless water heater. Most installation companies will also help dispose of your old water tank.

The amount of time it takes to replace an electric water heater will depend on the skill level of the individual who is replacing it. For example, if you replace it yourself–and you don’t have much experience–you can expect the project to take a full day. 

However, if you have a certified plumber or water heater contractor install your new water heater, it can take as little as 2 to 3 hours.

You don’t have to replace expansion tanks at the same time as your hot water heater. You may be able to go six to 12 years or more before needing to replace your expansion tank. At $150 to $450, hot water heater expansion tanks are usually much more affordable than the cost of hot water tanks themselves, which average about $1,190.

Your water heater's age can affect your homeowners' insurance policy. Many policies will ask how old the heater is when you first apply for a policy—and they may make you replace a model that's over 10 years old. 

Even if your policy permits you to have an older heater, it may significantly reduce the amount of protection available. If an older water heater suddenly leaks and causes damage to parts of your home, your policy may not cover it.