Re: [EnergyPlus_Support] Control strategies for combined radiant system and air system

["Michael J. Witte" <mjwitte@xxxxxxxx>]

With the current control options in EnergyPlus it is very difficult to
coordinate the operation of combined radiant and air systems serving the same
zone.  The air system will operate based on the heating or cooling load
determined by the zone thermostat (along with fan schedules, min flow
fractions, etc.).  The radiant system will operate only if there is a load
determined by the zone thermostat AND the radiant system controls are not
satisfied.  More flexibility is planned for version 1.3.0 to be release around
April 2005.

In the current version, to come close to what you want, try the following
settings for the radiant hydronic system:

1.  1.  Specify ODB control type.

2.  Set the throttling range to be the ODB range over which the system should
throttle from no flow to full flow.  For example, if the radiant cooling should
be off at 25C ODB and fully on at 35C ODB, then the throttling range would be
10C.

3.  Set the cooling control temperature schedule to be the midpoint of the
throttling range, which is 30C in this example.

4.  You will probably need to manually size the radiant hydronic system to
obtain the desired sharing of load between the radiant system and the air
system.

Mike


On 13 Sep 2004, at 13:41, zhen tian wrote:

> Dear All:
>
> Is there any possibility to set up different control strategies for the radiant
> system and indepedent air system?  I mean, the radiant cooling system is
> controlled by the building central control while the air system is conrolled by
> the zone thermostats.
>
> I understand that an alternative solution is to set up minimum air flow rate to
> let the radiant system run all the time in the cooling season.  But I just want
> to find out how to coordiante air system and radiant system.
>
> Thanks a lot.
>
> Regards,
>
> Zhen
>
>
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========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support
EnergyPlus-Support@xxxxxxxx




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