Home Improvement

What is bypass VAV?

The bypass VAV terminal is a device that receives a constant volume into the unit and provides variable volume to the space. It diverts a portion of the supply airflow to the plenum, either through a duct to the return ductwork, or directly into a return air plenum.

What is changeover bypass VAV?

Changeover-bypass VAV is a comfort system developed for light commercial applications. A changeover-bypass VAV system responds to changing cooling or heating requirements by varying the quantity or volume of air delivered to each zone. Each zone has a thermostat for individual comfort control.

What is VAV and how it works?

VAV stands for Variable Air Volume. In its simplest form, VAV systems use varying airflow at a constant temperature to heat and cool buildings. This is opposite of a CAV (or Constant Air Volume) system, which supplies consistent air flow at varying temperatures to heat or cool a space.

How many types of VAV are there?


There are two major classifications of VAV boxes or terminals—pressure dependent and pressure independent.

What is a bypass terminal unit?

Nailor 3400 Series Bypass Terminal Units are designed to provide variable air volume supply when used with constant volume fan low pressure packaged air handling systems or roof-top air conditioning units. Excess air is diverted through a bypass opening and into the system return.

What is the difference between VAV and VRF?

VRF, variable refrigerant flow, is a more recent HVAC technology than VAV and uses refrigerant as its medium to heat and cool. Operating very similarly to a ductless mini-split system, a VRF varies the refrigerant flow via variable motor speeds to provide buildings the ability to control individual zones.

How are motorized dampers controlled when they are used as bypass dampers?

How are motorized dampers controlled when they are used as bypass dampers? A pressurestat measures the static pressure across the blower. A variable-air-volume system changes the amount of air the fan delivers in order to: Match the zone requirements.

How does bypass duct work?

This duct is known as bypass duct which has a bypass damper in it. the bypass duct builds a connection between your supply plenum and your return ductwork. The damper inside has the power to either restrict or allow air to enter the bypass based on the condition.

What is face and bypass damper?

Face and bypass dampers are standard control dampers assem- bled either (FBV) one over the other, (FBH) beside each other or (FBR) at right angle from each other. The units are interconnected for simultaneous blade action, typically causing one damper to open while the other closes.

What is a bypass damper and where would it be installed?

That is your bypass damper as a door inside of it it has a weighted arm to hold it shut and that seals against this gasket.

What is the purpose of the bypass dampers in Ahu?

Face/ bypass dampers typically modulate to force air to pass through the “face” of an AHU’s cooling coil or to “bypass” around them. In some cases, there are both heating and cooling coils present and these dampers mix how much air passes through each coil.

Why do we use damper?

A damper is a valve or plate that stops or regulates the flow of air inside a duct, chimney, VAV box, air handler, or other air-handling equipment. A damper may be used to cut off central air conditioning (heating or cooling) to an unused room, or to regulate it for room-by-room temperature and climate control.

How do you measure a bypass damper?

Bypass Airflow (cfm) = Unit Airflow (cfm) – All Zones Minimum Airflow (cfm). To size the damper, select a damper based on calculated bypass cfm and a maximum velocity between 1,750 and 2,250 FPM. When determining the bypass duct size, make sure to consider any transition fittings and associated pressure drops.