Re: [EnergyPlus_Support] Small School - Unit Heater

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

1. No.  The Unit Heater is zone equipment, it does not connect to an air loop.  
See unit heater example files and description in Input Output Reference.

2.  An exhaust fan can be used, or proper application of outside air controls.  
When using an air loop, there must always be a return path, even if the flow 
will always be zero.

3.  Probably.

Mike


On 25 Jan 2008 at 17:52, brandao_nuno wrote:

> Dear All,
> 
> I´ve been working on a small school simulation with heating only
> requirements. I´m reposting the system description :
> 
> I´m simulating a small school, with 4 controlled zones. All the zones
> are equipped with radiators. Two unit ventilators equipped with heating
> coils, supply air, each one supplying air to a group of two zones. The
> system is suppose to maintain the 4 controlled zones to a setpoint of
> 20ºC, so outside air is preheated to 20ºC by the ventilator's heating
> coil, and injected at that temperature into the zones. The radiators
> are responsible for the final heating requirement adjustments,
> although they have priority. The building has no cooling requirements.
> 
> The system is only functioning during occupancy hours with a 20ºC
> setpoint. It turns on when the temperature is below 20ºC and turns off
> if the temperature is above that value. Uses 100% outside air and it
> is not recirculated.
> 
> 
> I´m studying the possibility to use the "UNIT HEATER" component as an
> alternative to the "DIRECT AIR" solution. In I/O reference, this
> component is described as a zone equipment forced air unit, being a
> little bit different of the "DIRECT AIR" component, as this one is
> described as an "AIR DISTRIBUTION" component. I my simulation, after
> implementing this solution I´ve encountered several errors which
> brought confusion in my understanding of this alternative. My
> questions are as follow:
> 
> 1. First of all, is this modelling solution possible, having in
> account the system described above?
> 
> 2. How can I guarantee 100% outside air? Do I have to model a exhaust
> fan? It must always exist a return air path, even if the air flow is
> 100% outside air, right?
> 
> 3. This is the description of the 2 first severe errors, from the
> *.ERR:(I think the next 39 severe errors are consequence from the
> first ones.)
> 
> ** Severe  ** An outlet node in  Air Primary Loop AIR LOOP2 is not
> connected to any zone
>    **   ~~~   ** Could not match ZoneEquipGroup Inlet Node="ZONE
> SPLITER2 AIR INLET NODE" to any Supply Air Path or controlled zone
>    ** Severe  ** An outlet node in  Air Primary Loop AIR LOOP1 is not
> connected to any zone
>    **   ~~~   ** Could not match ZoneEquipGroup Inlet Node="ZONE
> SPLITER1 AIR INLET NODE" to any Supply Air Path or controlled zone
> 
> Is this related to any impossibility to couple zone splitters with
> this kind of component(UNIT HEATERS)? Can I use two zone splitters(one
> for each air loop) and connect them directly to the zones, with a zone
> air inlet node? I´m a bite confused...
> 
> I´m uploading my idf file so that you can have a look at it.
> 
> Thank you very much for the help
> Nuno Brandao
> 
> 
> 
> 
> 
> 
> 
> The primary EnergyPlus web site is found at:
> http://www.energyplus.gov
> 
> The group web site is:
> http://groups.yahoo.com/group/EnergyPlus_Support/
> 
> Attachments are not allowed -- please post any files to the appropriate folder
> in the Files area of the Support Web Site.
> 
> EnergyPlus Documentation is searchable.  Open EPlusMainMenu.pdf under the
> Documentation link and press the "search" button.
> 
> Yahoo! Groups Links
> 
> 
> 
> 
> 


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





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