RTM Engineering Consultants completed the third webinar in our monthly broadcast series aimed at educating the architecture and commercial real estate community on new engineering processes and best practices. This month, the session focused on the use and application of variable refrigerant flow (VRF) and why this technology has become an industry leader around the world for use in AC systems.

VRF systems are very flexible and ideal for energy-efficient and comfortable cooling and heating of various building types including commercial and residential facilities. Once installed, these systems require very little maintenance, making them a desirable option for owners.

The webinar highlighted four commonly used systems for refrigeration worldwide: direct-expansion (DX) – standard design ranges from 1-25 tons; chilled water – standard design ranges from 60-1,000 tons; heat pumps with cooling towers – standard design ranges from 100-1,000 tons; and VRF –varying size options from small to large systems.

Other topics covered by presenter Dale Adney, P.E., at RTM, included:

  • VRF components – VRF is built upon four basic “building blocks”: outdoor unit, indoor unit, piping, and controls
  • Designing a basic VRF system for a building – a review of system and design requirements as well as considerations for architectural and mechanical coordination
  • Safety standards for refrigeration systems – two main factors to consider are the system’s flammability and toxicity

Listeners were interested to know how outdoor air is typically brought in when using VRF systems. Adney explained that VRF systems require a fully outdoor makeup air unit that heats and cools to provide tempered outside air. The outside air is not intended to heat or cool the space and is supplied at a neutral room temperature. The outdoor air would be ducted either to the space directly or to the return of the VRF unit as a means to provide ventilation.

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