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Re: [EnergyPlus_Support] Re: DX coils consistency with ASHRAE 9.1-2007 Tab6.8.1A for a Baseline VAV system 5 with reheat



Let me start by saying that "the deeper you dig, the deeper the rabbit hole will go". The true answer and understanding of your questions are at a level Jim Dirks has well described as "black belt level". I'm not going to start explaining it all.

According to me, and there are other opinions out there, the most responsible way is to use the data derived curves of a equipment in the e+ database available to you. Choose the equipment (curves) that most closely match yours for type and full load capacity. Then adjust the rated fan power to the required value. Then adjust the rated gross COP until the reported net COP matches the requirement. The part-value requirement like IPLV or SEER will not match. If the baseline equipment is better than the minimum requirement, then it is conservative and you should be okay with the reviewer.

 

Thank you Jean for the reply.

That is what I suspected. About this this I have one or two more doubt.
I can't figure how to calculate the gross COP to make the standard rated net cop to be consistent with ashrae limitations.

The easiest way is to set up a parametric analisys to find the correct net COP varing the gross COP, but I found that also   !- Rated Evaporator Fan Power Per Volume Flow Rate {W/(m3/s)} set at the default 773.3 has an effect on net COP as well as on SEER and IEER.
The I/O ref seems to suggest only to change the 773.3 to obtain pvorrect values for SEER and IEER. In this way the parametric analisys shoul be performed with 2 parameters.

In my opinion this should not be the best way to solve the problem because it implies a sort of "blindness".
Looking for an help I found some examples on ASHRAE 90.1 user manual (examples  11-C and G-G) in which there are showed the calculation which involves the net and gross COP. Even if I found that the same calculations can be repeated using data reported in the html file ans obtaining analitically in this way net or gross cop, those calcs are performed not using user input from the idf.

I don't know if I have been clear in the previous description, but my question is this... in which way should I set the gross cop? Which approach should I follow? In which way should I manage the input   !- Rated Evaporator Fan Power Per Volume Flow Rate? Must I satisfy the consistency of IEER an SEER?

Thanks



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Posted by: Jean Marais <jeannieboef@xxxxxxxxx>


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