Outdoor Air Damper Control

Exhaust air damper x h.

Outdoor air damper control.

The fresh air damper fad is a 24vac power open power close motorized air damper designed for installation in a fresh air ventilation duct connected to an outdoor air intake hood and a duct fan or the hvac return plenum to control the flow of fresh air into the home. A properly designed installed operated and maintained oa damper will preclude the entry of water rain snow into the ah system and will stop the flow of air into the system when it is closed. The return air temperature the 70 return air damper position. Finally the bas sends this outdoor airflow setpoint to the rooftop unit which modulates a flow measuring outdoor air damper to maintain this new setpoint.

Outside air damper will close. The return damper damper 2 figure 1 and outside air damper damper 3 figure 1 are controlled via discharge air or mixed air temperature as part of the economizer cycle. As the outside air damper opens beyond minimum the return damper moves toward a closed position. This is a quick way to tell if something is amiss with your damper control.

Install controls to provide intermittent fresh air based on a timer. The outdoor air damper shall open whenever the fan is energized and closed when the fan is off. When an outdoor air inlet is ducted to the return side of the hvac system s central air handler install a motorized damper that can close the air intake. From rectangle to round hvac dampers johnson controls offers air damper controls in a diverse range of models that prevent outside air from penetrating your building.

For example if you have 10 outdoor air damper at 100 degrees outdoor air and 90 return air damper at 74 degrees return air your mixed air temp should be 76 6 degrees. 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. Manual dampers are turned by a handle on the outside of a duct. When schedule calls for occupied mode startup and the return air temp is 5 f or more below setpoint 70 f a warm up cycle shall initiate.

Warm up cycle control wcc 1. In a ddc vav system this strategy is fairly easy to implement because the necessary real time information is already available digitally.