expansion tank

Water Heater Thermal Expansion Is Dangerous!

Do you notice water at the base of your water heater occasionally? Did you discover that the leak is coming from the relief valve at the top of the water heater? If you have this problem, it could get a lot worse if you let it go!

Thermal expansion tank

Is a small tank used for hydronic hot water heating systems and domestic hot water heaters. It protects either system from water hammer and thermal expansion resulting from being closed and not open to atmospheric pressure.

Where does it get installed?

Typically an expansion tank is used for a water heater when there is a backflow preventer, or pressure reducing valve installed after the water meter. A good place for a thermal expansion tank on a water heater installation is anywhere on the cold water pipe between the water heater and water meter. Preferably upstream of the water heater is the preferred location.

Get a little relief…

water heater relief valve

When a water heater cycles the heated water, expands into the cold water piping all the way to the main water service. If it can’t expand, it builds up thermal expansion (or higher pressure than normal) eventually causing the relief valve (or safety valve) on the water heater to drip. A water heater that does not have the proper thermal expansion relief can be problematic.


If you let the water drip from the relief valve on your water heater, you’re going to get a high water bill. Most importantly you’re taking the risk of causing significant property damage, getting yourself severely injured or even causing death. Watch the video below to see that I’m not exaggerating:

Don’t let it go

You’ve just seen a water heater go through a roof. Before you see this again in your house, click here for a water heater inspection. Have Vince, an experienced plumber in Pittsburgh who knows the difference between a good or bad relief valve inspect your water heater.

Safety comes first, doesn’t it?

Carbon Monoxide Safety Check

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