View Full Version : vav min and max settings
09-27-2006, 10:04 AM
Im looking for generel guide lines or rule of thumb (if any) for min and max vav settings.Scenario #1 is interior highrise office space cooling only (no reheat). Scenario #2 is perimitor heating without reheat (perimitor heating is assomplished by cieling mounted radient heat panels set to operate when outdoor ambient drops to approx 57 deg-F.Scenario #3 is min max for perimitor heating with hotwater reheat coils. Does the perimator exposure (N-S-E-W)factor into the min, max settings of perimator zones.The above scenarios have controlled static feeding tyhe boxes and are equiped with pressure independant controllers.
Your input is appreciated.
09-30-2006, 11:51 AM
the minimums are set to provide fresh air at all times. maximums are determined by a load calculation for each individual zone. dont forget to check out the economizer, make sure it's functioning properly and at it's minimum setting is meeting the building's fresh air requirements.
09-30-2006, 12:19 PM
I agree with Min / Max Heat load and Fresh Air. All Based off load (Room, People, etc)
You will have to also Get Manuf, Data on box, Heat loss, Size, etc to help properly set up box, etc (might be attached to VAV) also consider the duck restriction, registers used!
What type of controller? DDC or puma tic? (Search form for controller type, might help)
Where I’m going is – I find Most (calibrating) VAV was not set up right, or things (room) has changed. Also using the right tools to set up VAV/Controller solves most problems, also Air Balance (Hood) tools are a must- there is a say a % error range acceptable, or all is for naught.
Besides min / max flow (A simple example: 50 cfm per drop min for “fresh air” and 100 cfm max for “ cooling” , say 4 drops would be 200 min / 400 max and some “controllers need a setting for Nominal flow, or “typical” for Box/space, some manuf, use 25% for cooling and 30% for reheat box’s)
There is a whole science behind this Air (VAV) Balance stuff – for a particular area (heat load) and VAV manuf, size/loss/ and controller, etc,
But with studying your needs! And the right Tools
It’s easy to do.
10-03-2006, 07:57 PM
Every vav connected to the same air handler, work together to distribute the air from the AH to the side of the building that need it most. Different side of the building need different capacity as the sun move across the sky. Bottom line is that an Air balancer should make the max/min determination.
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