Re: [EnergyPlus_Support] Baseboard in combination with Direct Air did not work as expected

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

My apologies for the holiday delay in sorting out this request.  

It appears that the baseboard control logic does not recognize that the zone is 
in the thermostat deadband.  "Zone/Sys Sensible Load Predicted" is zero.  The 
18C DIRECT AIR cools the zone, and the baseboard turns on to offset the cooling 
from the ventilation air, seeking to provide a net load of zero to the zone.  A 
Change Request has been posted to fix this problem.

You can accomplish the equivalent simulation using SINGLE DUCT:CONST 
VOLUME:REHEAT instead of DIRECT AIR plus baseboard.  The SINGLE DUCT:CONST 
VOLUME:REHEAT control logic does not have the same problem.  When the zone is 
above the heating setpoint, the reheat coil is off.

I will send the equivalent test file using reheat in a separate e-mail.

Mike


On 20 Dec 2005, at 14:44, christian1855 wrote:

> Mike, Linda
> I'm currently model a office building. The zones have three 
> equipments: a low temp radiant system hydronic, a direct air component 
> and a baseboard heater. 
> Now in the winter period sometimes the baseboard heater heats the zone 
> even when the zone temperature is above the zone setpoint temperature!
> Now this is very strange. So I'll tried to track the problem down. 
> I've simplified the model to a one zone model. This zone will be 
> served with constant 18°C air via a direct air component and have a 
> baseboard heater electric. This simple model has the same problem. The 
> baseboard heater heates (at low level) even when the zone temperature 
> is above the zone setpoint temperature!
> 
> I'll upload the idf file:
> baseboard_with_directAir_setpoint_problem.zip
> 
> Christian
> 
> 
> 
> 
> 
> 
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> 
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> 
> Attachments are not allowed -- please post any files to the appropriate folder
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> 
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> "search" button.
> 
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> 
> 
> 
> 
> 
> 
> 
> 
> 



========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support      
EnergyPlus-Support@xxxxxxxx




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