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Re: [EnergyPlus_Support] VRF question

Hi Ery,

(1) The operating mode of the VRF system can be zero on three conditions:
     (a) when the VRF system is scheduled off
     (b) if there are no cooling and heating loads
     (c) the outdoor condition is outside the operating limits of the VRF system

(2) A terminal unit output is expected to be the same as the zone load, provided there is enough capacity.  And the sum of the terminal units output is expected to be equal to the total zones heating or cooling loads. The total zones being the zones connected to a single VRF system. 

However, just like a single speed heat pumps, the capacity of the VRF system is function of the outdoor condition; with decreasing outdoor air temperature, the heating capacity decreases. There could be other factors that may affect the unmet hours. If there is enough capacity, then the system or the terminal units should always deliver the requested zone heating loads.  It is difficult to give clue without looking at the input file.

Hope this helps,
Bereket Nigusse


--- On Wed, 1/30/13, erydjunaedy <ery.mailinglist@xxxxxxxxx> wrote:

From: erydjunaedy <ery.mailinglist@xxxxxxxxx>
Subject: [EnergyPlus_Support] VRF question
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Date: Wednesday, January 30, 2013, 11:29 AM
















 



  


    
      
      
      Folks,



1. Is there a reason why the VRF operating mode becomes zero (=OFF)? Should it not be always cooling or heating (1 or 2)?



2. Is there a limit to the coil output? I found a case where the coil output is getting lower and lower causing unmet setpoint. The lowering of coil output coincides with the lowering of zone heating load.



Thanks,



Ery





    
     

    
    






  











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