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Maryland State Government Maryland Department of the Environment

FACT SHEET
Vent Alarms on Your Home Heating Oil Tank

What is a vent alarm? A vent alarm is a small device, usually a tube, which is typically installed between your tank and the vent pipe. It signals that the tank is full, thereby minimizing the chance of overfilling.

Why install a vent alarm? A vent alarm system will help prevent a release of oil into your cellar or into the environment due to accidental over-pumping of oil into a full tank. The cost to cleanup an accidental release of heating oil can range from several hundreds to thousands of dollars. The cleanup of heating oil contamination can take from several weeks to several years, depending on the magnitude of the problem. Cleanups of oil contamination are disruptive to your property and lifestyle. A vent alarm can help prevent these problems.

How does a vent alarm work? When oil is pumped into your tank, air is displaced from inside the tank through the vent pipe. As the air passes through the vent pipe, it makes a whistling sound as it passes through the alarm. When the level of the fuel reaches the end of the tube the whistling stops, which indicates that the tank is full.

How do I know if I have a vent alarm? Ask your fuel oil dealer or your heating specialist if there is a vent alarm system installed in your tank the next time your fuel oil storage tank is filled.

How much does a vent alarm system cost? Depending on the configuration of your tank, the price of a vent alarm ranges from $20 to $50 (plus installation). Your oil dealer can install the vent alarm. In some cases, the dealer may perform the installation at no cost to help you ensure that deliveries to your tank are made with minimum risk of environmental contamination and liability.