Make-Up Air

Related terms

• Manifold / Home-Run

  A PEX distribution method with individual lines from a central manifold to each fixture, improving pressure balance and isolation.

• Main Shutoff Valve

  The valve stopping all water to the house. Every homeowner should know its location; remodels often add accessible zone shutoffs.

• Manual J Load Calculation

  The industry-standard room-by-room heating/cooling load calculation that correctly sizes equipment. The right basis for any system replac…

• Main Breaker

  The single breaker that disconnects the entire panel and caps total service amperage.

• MERV Rating

  Minimum Efficiency Reporting Value — a filter's particle-capture rating (1–16). Higher filters more but can choke airflow if the system i…

• Load Calculation Oversizing

  Installing equipment larger than the calculated load — a frequent mistake that causes short cycling, poor dehumidification, and higher cost.

• Meter Base

  The utility meter socket on the service entrance; replaced or relocated as part of a service upgrade.

• Load Calculation (Electrical)

  An NEC calculation of total demand to verify the service/panel can carry added loads. The basis for whether a service upgrade is required.