Control zone.

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Hi All,
What is the exact meaning of control zone ,and what is the reason
that by chaning the control zone our unmet hours gets reduced.

Please if any one can answer it i asked this dobut so many times but could
not get the reply.

Any response will be highly admirable.

Thanks
Sambhav.

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Sambhav

When you have a multizone system where there isn't individual zone
control from either zone units or terminal devices there must be one
zone where the thermostat controls the operation of the multizone
system, typically this would be the case with a constant volume rooftop
unit for example. One zone has to ultimately control the system so that
zones aren't fighting each other to satisfy the setpoint.

The number of unmet hours can be reduced by selecting a zone that
represents the load fluctuation of the other zones more closely.

Alan Jackson, LEED AP

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The control zone is the zone you have picked out of the group of zones
where the t-stat is located. An air side unit will supply conditioned
area to all these zones and be controlled by the T-stat and the
conditions in that particular zone. All the other zones get whatever
fraction you have assigned to them from the air side unit. Sometimes if
you have selected a zone not representative of the group you will get a
lot of under or over cooled hours. One of the ways to get them down is
to select a different control zone out of the group. Depending on why
you have these hours this solution may make a big difference or no
difference. The control zone should be the zone which is the hardest to
heat or cool. It is just trial and error after a good judgment guess.
Don't forget to "save as" to get yourself a copy before you start to play.
Bruce Easterbrook P.Eng.

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