Do I Really Need an Expansion Tank on My Water Heater?

These tanks look like small propane tanks either on top of your water heater or off to the side. They are only required when a water system has been made into a closed loop.

What that means for the Frisco, McKinney, and Plano area is that if you have a PRV (Pressure Reducing Valve) installed then you are required by code to have an expansion tank installed.

Expansion tanks are required for traditional tank-type water heaters only. They are NOT required for tankless water heaters unless specified by the manufacturer.

How do you know if you have a PRV? Unless you have had water pressure issues or you’ve had one replaced, then you probably don’t know. But a good rule of thumb is if your home was built after 1999, it’s possible you have a PRV. If you live in Frisco, McKinney, Little Elm, or Prosper then you must have a PRV by city code. Less than 30% of homes in Plano have them, and less than 10% of homes in Allen.

Here are the most important things that you MUST know about expansion tanks:

• It is a steel tank with water inside. Eventual failure is inevitable. Be proactive.
• They will NOT last as long as the water heater, and they must be changed periodically. We recommend every 3 years, but 5 years at a maximum.
• Property damage by leaking expansion tanks is probably more common than a leaking water heater. The amount of damage depends on the seriousness of the leak (drip, spray, or full rupture).
• They must be installed horizontally, and when NOT installed properly, they will fail at a higher or more frequent rate. Improper installation can reduce hot water flow rates.

Once again, we recommend that you be proactive in replacing your tank water heaters and your expansion tank should this apply to you.