HVAC Barometric Dampers 1

[flyinghigh]

An HVAC unit is rated at 2400 cfm at 0.8"wc and 75,000 Btu/h. You're going to subdivide its zone into two zones with motorized dampers. To prevent icing of the unit in summer, and overheating in winter, you're going to install a barometric damper between the supply duct and the return ducts, which are both 30 x 12".
The motorized dampers, when instructed to close by the smaller zone thermostat, will close off a flow of 800 cfm. I'm assuming the barometric damper should be sized to flow this same amount. How do you size the barometric damper?
The control sensor for the barometric damper will be installed in the supply plenum or duct. Where should it be set, at 0.8"wc?

 

[cdxx139]

Is the unit a constant volume unit?
By adding a bypass damper, you are keeping the unit constant volume, but the termonal unit variable volume?

Sounds like you are describing the Carrier VVT system or the Trane Varitrac system. I suggest you look into them, instead of reinventing the wheel.

knowledge is power

 

[willard3]

From forum policies which you should follow:

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Hire a Mechanical Engineer to do this work and stop trying to bootstrap on this forum.