In HVAC an area within the interior space of a building, such as an individual room(s), to be cooled, heated or ventilated. A zone has its own thermostat to control the flow of conditioned air into the space. Zoning

Defined as the total air, which is a combination of the air brought inside from outdoors and the air that is being re-circulated within the building. Sometimes, however, used in reference only to the air brought into the system from the outdoors; this document defines this air as “outdoor air ventilation”. Ventilation Rate

HVAC term for the duct(s) of a forced air heating/cooling system through which heated or cooled air is supplied to rooms by the action of the fan of the central heating or cooling unit. Tankless Water Heater

Air that is returned to a heating or cooling appliance from a heated or cooled space. Return Duct

Air removed from the conditioned space and used for ventilation, heating, cooling, humidification or de-humidification. Refrigerant

A type of thermostat that allows the user to program into the devices’ memory a pre-set schedule of times (when certain temperatures occur) to turn on HVAC equipment. R-Value

HVAC term for air compartment to a duct or ducts. Positive Pressures

In flowing air, the total pressure minus velocity pressure. The portion of the pressure that pushes equally in all directions. Preventative Maintenance

Air taken from the external atmosphere and, therefore, not previously circulated through the system. Outdoor Air Supply

Minimum Efficiency Reporting Value, is a measurement scale designed to rate the effectiveness of air filters. For the particles in the range of 0.3 to 10 micrometres the MERV rating is from 1 to 16. Higher MERV ratings correspond to a greater percentage of particles captured on each pass, with a MERV 16 filter capturing more that 95% of particles o [..]