Furnace Filter Whistle

A clogged or dirty furnace filter can rob your furnace of energy efficiency. Knowing when to replace your furnace filter will enable you to keep your furnace more energy efficient, saving you energy in the long run. The furnace filter whistle sounds when your filter becomes 50% clogged letting you know it will soon need replacing. Helps to maximize efficiency of filters used for heating and air conditioning. Available individually packaged with use instructions (see below) or may be custom packaged with your logo, message or program theme.