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Frequently Asked Questions

   1. What is Thermal Expansion?

Thermal expansion refers to the characteristic of water to expand when it is heated. Unlike air, which can be compressed, water grows in volume, and must be accommodated.

2. Why is Thermal Expansion occurring?

In a water heater, thermal expansion can create more pressure than the system can handle. When unchecked, this pressure can result in expensive leaks, as well as damage to the water heater, pipes, or other fixtures.

3.When is a Thermal Expansion device necessary?

Thermal expansion is necessary when any of the following occurs:

• A recent water meter replacement

• A hot water heater replacement

• The construction of a new home

• When a backflow preventer is installed on the water

(Water heater without an Expansion Tank)

4. How do I resolve this Thermal Expansion

Thermal expansion can be solved by installing an expansion tank to your system adjacent to your water heater. This tank will accept overflow from your water heater, alleviating the pressure building up in the heating tank. Expansion tanks are inexpensive and the most conservation-friendly solution. There are also several other relief solutions available. Talk to your local plumbing or hardware vendor regarding these alternatives.

5. I have a Temperature and Pressure Relief (T&P)

No. A T&P valve is not a thermal expansion device, because the constant dripping of water from the valve can result in a mineral deposit that can create a blockage, causing the T&P valve to become ineffective. Plumbing standards and codes require that thermal expansion be properly addressed.

(Water heater with an Expansion Tank)
The expansion tank’s size, color, and position may vary. Tanks are commonly installed in a low or high upright position.

 6. Where can I get this device?

Thermal expansion solutions are available at Ace Hardware, True Value stores, or your local plumbing and hardware vendor.

 7. If you have further questions regarding the thermal expansion
requirements and alternatives check the The Meter Services Division website at: or contact:

Meter Services Division
Backflow Prevention
at (404) 270 - 7096 or (404) 270 - 7097

 8. What is backflow-prevention?

It is the prevention of reverse flow in a water system from the normal or intended direction.

 9. What can cause something like this to happen?

Backflow and/or backsiphonage can occur in a water system by a drop in supply pressure due to heavy demand or use such as fire fighting, or by repairs or breaks in the supply pipe, etc.

Georgia Certified Backflow Testers

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East Point, Georgia 30344