[Equest-users] COOL-CTRL-RANGE

[Aaron Powers]

Luca,

The COOL-CTRL-RANGE is a parameter used to model the proportional offset
for a controller which controls the cooling coil.  In a system with
variable air volume and a chilled water valve, there are two methods for
modulating cooling capacity: i.e. you can reduce the air flow or reduce the
water flow.  Since you have two actions to modulate capacity, you need two
independent setpoints to control these actions.  Typically, the cooling
coil valve is controlled to maintain a supply air temperature setpoint.  If
you don't specify a supply air reset method, the supply temperature
setpoint is the "Zone Entering Min Supply Temp" (MIN-SUPPLY-T in BDL)
parameter which defaults to 55 deg-F.  So, if you were to specify a
COOL-CTRL-RANGE of 4 deg-R, the controller will call for 100% action at 57
deg-F and 0% action at 53 deg-F.  This is what is meant by Tmax and Tmin:
they are the cooling supply setpoint + or - 1/2 the control range.  The air
flow is then modulated to meet the space temperature setpoints given the
supply temperature.  9 deg-F seems a little high for any system.  You
typically see a range of only a few degrees in practice, unless there is
something wrong with the controls.

Aaron


Hello all,

I am modelling a building in eQuest: I am not really sure what the
COOL-CTRL-RANGE parameter refers to.
In the eQuest tutorial it says: "Throttling range of the cooling coil
controller. It equals Tmax - Tmin where Tmax is the temperature of the coil
when it is fully loaded and Tmin is the temperature of the coil when it is
fully unloaded."
what is exactly meant with Tmin?
Is a value of 9ºR realistic with a VAV system?

thanks in advance for your time,


Luca

-- 
*___________________________________________________________

*
*Luca Volpi** *Arch. Dipl.-Ing.
Societat Orgànica | Europa, 15 2.4 | ES-08028 | BCN | +34 93 430 7653
www.societatorganica.com | lvolpi at societatorganica.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20130403/c1e2dea7/attachment-0002.htm>