How does an expansion tank affect Drip Detect™?

How to determine if you have an expansion tank:

An expansion tank is a small tank that can generally be found near your hot water heater. One way to tell if you have an expansion tank is to find your water heater, and look for a small, propane-like tank. This is the most common location for an expansion tank. It is also possible that you have an expansion tank connected to your water line somewhere else. If you can’t see your expansion tank, you can shut-off your main water valve and then turn on HOT water from any faucet in your house. If no water comes out, it is unlikely that you have an expansion tank. If water runs for about 10 seconds and then stops, you likely have an expansion tank.

NOTE: If you have a tank-less water heater, then you will not have an expansion tank.

How can an expansion tank affect Drip Detect™?

An expansion tank can effect Drip Detect in two ways:

• False Negative: An expansion tank can create a False Negative Drip Detect test. In other words, an expansion tank can make it difficult for the Control to detect TINY drips (drips less than 1 drip per minute). If you do not have an expansion tank, the Control will be able to detect a drip as small as 1 drip per minute.
• False Positive: If you use a very small amount of water during the Drip Detect test (ice machine running, filling up a glass of water, etc.) the Control may alert you of a leak that does not exist. Remember, no water should be running during a Drip Detect test. Without an expansion tank, the Control would be able to detect any water usage during a Drip Detect test and would postpone the test an hour. An expansion tank makes it difficult for the Control to tell the difference between a leak and small water usage during a Drip Detect test.