HVAC Filter Replace Manometer

Pressure drop is the best way to detect when your HVAC filter needs replacing. Generally you should replace the filter when the pressure drop across it doubles from its initial clean state. Alternatively, for most residential systems, a 0.5-inch water column pressure difference is considered the threshold for replacement. Your HVAC system may be different depending on the filter. Visual inspection of the filter or waiting 3 months is less reliable. The pressure difference is usually measured with a magnehelic gauge, a digital or U tube manometer, you can buy one online or make this simple type. A magnehelic gauge is the most expensive (more than $100) but always shows the pressure difference. A digital manometer is around $50 and a U-tube manometer is $10 to $20 and is always showing the pressure difference.. This manometer shows the pressure difference between the two sides of your HVAC filter. As the filter gets more clogged by particles captured the pressure will increase. When the