[EnergyPlus_Support] Re: Small School - Unit Heater

["brandao_nuno" <ncostab@xxxxxxxxx>]

This is the last of two posts reposted.
I'm really desperate for some help here!

Thanks in advance
Nuno Brandão

-------------------------------------------------------------------
> 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
>




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