[Bldg-sim] Controlling heating with outdoor temperature

[Carol Gardner]

Here's some info:


 Volume 2: Dictionary <volume2dictionary.htm> > HVAC
Components<hvaccomponents.htm>>
SYSTEM <system1.htm> > Airside Control <airsidecontrol.htm> >
HeatingAvailability and Supply
Temperature<heatingavailabilityandsupplytemperature.htm>
HEAT-CONTROL

Takes a code-word that specifies how the air temperature leaving the system
heating coil is controlled. Allowed values are:

CONSTANT                  The supply air temperature is held nearly constant
at HEAT-SET-T; it can change a few degrees due to fan heat and throttling
range of the temperature controller.

COLDEST                    Sets the heating coil (hot deck) temperature each
hour to adequately heat the zone with the lowest temperature. The limits on
the supply air temperature are governed by coil capacities,
heatingschedules, and MAX-SUPPLY-
T. WARNING: If using the COLDEST or WARMEST options in conjunction with a
variable air volume system, there are two actions within the throttling
range. To reflect reality and to prevent instability in the simulation,
THROTTLING-RANGE should be increased to 4-6F (2-3K).

RESET                         Specifies use of HEAT-RESET-SCH for control of
heating air supply temperature based on outdoor air temperature.

SCHEDULED                Specifies use of HEAT-SET-SCH for control of
heating air supply temperature.

In SYSTEM TYPEs VAVS, RHFS, PVAVS, and PIU the HEAT-CONTROL keyword is
activated when COOL-CONTROL is set equal to WARMEST and a central
heatingcoil has been specified by giving
HEAT-SET-T a value greater than MIN-SUPPLY-T; in this case the only
non-ignored value for HEAT-CONTROL is COLDEST. When coldest/warmest control
is specified the controller first looks to see if any ZONE has a cooling
demand; if there is a ZONE cooling demand the AHU discharge temperature is
reset to attempt to just satisfy the ZONE with the largest cooling demand.
If no ZONE has a cooling demand the controller looks to satisfy the ZONE
with the greatest heating demand but without forcing any ZONE into creating
a cooling demand. If neither a heating or cooling demand is found for any
ZONE mixed air is passed.


On Fri, Nov 12, 2010 at 3:33 PM, Katherine Louman-Gardiner <
klgardiner at flowgroup.ca> wrote:

>  Hi All,
>
> My boss wants me to model a large AHU as a space by itself.  Our client is
> running the heating loop at night (when it’s below 40F), despite the fans
> being off.  There is also a very leaky damper allowing fresh air in to the
> space.  (I’ve got no cooling, and a fan mimicking the leaky damper).  It’s a
> wasteful practice, but we’re trying to quantify How wasteful it is.
>
>
>
> My question is:
>
> Is there a way to have the heating turn on/off based on an outdoor
> temperature?
>
>
>
> Since I couldn’t find a way, I created a dummy zone with only ventilation
> and no heating – but I still couldn’t figure out a way to use the
> temperature in the dummy zone to control the main zone.  The only way I
> could think of was  Pkgd Single Zone, but that added cooling and a condenser
> that I couldn’t get rid of.
>
>
>
> Anyway, Thanks for the help.  If I’m going about this the wrong way, I’d
> appreciate any feedback.
>
>
>
> Thank you.
>
>
>
>
>
>
>
> Katherine Louman-Gardiner, EIT
>
> Mechanical Engineer
>
>
>
>
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-- 
Carol Gardner PE
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