[Equest-users] Questions regarding Heating Coil sizing for 3.65.7175

Thu Sep 26 22:32:04 PDT 2019

Hey Sorry for the delay in my response - I (and perhaps a number of others who might otherwise see & respond) am attending the building energy conference this week in Denver.

Here's my take:

  1.  To distinguish/understand addition rate vs heating rate, I would refer you to the following resource, from which I'm highlighting a page addressing and explaining the SV-A report in further detail.  Note I personally reference this PDF as a primary/starting resource anytime I too am unsure of the nuances/meaning of specific SIM outputs:

[cid:image004.png at 01D574B7.50C45920]

[cid:image002.png at 01D574B8.A0F51B40]

That you have zonal heating set to 'None' is in fact reflected in the zeroes under heating rate (in the provided attachments).  I think you may constructively consider ADDITION RATE (and its counterpart EXTRACTION RATE) to be indicators from the LOADS portion of the simulation run, used to inform the autosizing for the whole systems auto sized airflow capacity (which you haven't specified).

  1.  I apologize, but after re-reading #2 a few times I'm unclear on what specifically is being asked.  Please rephrase =).
  2.  I suspect the 74F stat in your project is the calculated net result of the return air in the heating design day to the furnace after considering the system coil leaving temperature, internal heat gains, and whatever may exist for heat losses in the space(s) served.  In a system NOT involving a DOA, I would intuitively expect this to reflect the mixed air temperature (return + OA), but in your case a DOA is covering the ventilation it appears so I think perhaps MA = RA?
  3.  Once again, I think the detailed sim output reference provides some clues.  It's fair to note that there isn't an entry (at the time of this writing) in that PDF resource for some of the newer (?) reports like SV-C for coil sizing, but pay mind that the 'S' in the SV-C report indicates it's reporting from the SYSTEMS portion of the simulation run, which follows and builds upon the LOADS portion of the simulation ('L' in LS-A).  That context helps with interpreting the paragraph I've boxed in the following snip:

[cid:image005.png at 01D574BC.769E57E0]
                I'm curious if in your model you might find a matching (or a third) time and date stamp when checking the 'Standard' LS-A over the DESIGN DAY LS-A.  Regardless, it would seem apparent that the SV-C report is incorporating OADB conditions in your weather file whereas the LS-A you provided a snippet of is relying upon your DESIGN DAY inputs & sizing ahead of the listed effects introduced in simulation including ventilation loads, motor heat, plenum light heat...

I hope that makes some headway into clearing the air!

Nick Caton, P.E., BEMP
  Senior Energy Engineer
  Schneider Electric of North America
  Energy and Sustainability Services
  Energy Performance Contracting
D
M
F
E
913 . 564 . 6361
785 . 410 . 3317
913 . 564 . 6380
nicholas.caton at se.com<mailto:nicholas.caton at se.com>
15200 Santa Fe Trail Drive
Suite 204
Lenexa, KS 66219
United States
[cid:image006.png at 01D515A3.47EDD880]

From: Kathryn Kerns <kathryn.kerns at bceengineers.com>
Sent: Thursday, September 26, 2019 3:57 PM
To: Nicholas Caton <Nicholas.Caton at se.com>
Subject: FW: Questions regarding Heating Coil sizing for 3.65.7175

________________________________

Nick, I haven't heard back from anyone so there is probably no clear answer. Do you know how to contact anyone responsible for eQuest's latest revision that might be able to answer these questions? I would really like an answer to Question #3 about where the heat capacity sizing EDB\EWB comes from. It really doesn't make any sense. I know the HX is not providing the EDB\EWB listed, around 72 F. It should be more like 55 F.

Kathryn Kerns
Systems Specialist
BCE Engineers, Inc.
| Ph: 253.922.0446 | Fx: 253.922.0896 |

From: Kathryn Kerns
Sent: Tuesday, September 24, 2019 4:43 PM
To: equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>
Subject: FW: Questions regarding Heating Coil sizing for 3.65.7175

Everyone, I seem to have sent the message without the files. See attached.

Nick, thanks for calling.

Kathryn Kerns
Systems Specialist
BCE Engineers, Inc.
| Ph: 253.922.0446 | Fx: 253.922.0896 |

From: Kathryn Kerns
Sent: Monday, September 23, 2019 1:10 PM
To: Equest-users <equest-users-bounces at lists.onebuilding.org<mailto:equest-users-bounces at lists.onebuilding.org>>
Cc: Joshua Wood <joshua.wood at bceengineers.com<mailto:joshua.wood at bceengineers.com>>
Subject: Questions regarding Heating Coil sizing for 3.65.7175

Everyone, I have been  looking at the SV-A and SV-C reports for eQuest 3.65.7175 and I am confused. I have a zone with a typical PSZ furnace/DX with no reheat HVAC system related an auxiliary gym space.

The heating parameters are defined in the attached files called 218-112 Totem Base1 PSZ Furnace,DX, NoReheat Parameters and 218-112 Totem Base1 PSZ Furnace,DX, No Reheat HTG Parameters.

The resulting 218-112 Totem Base1 PSZ Furnace,DX, No Reheat SV-A & SV-C file (see attached) shows a Heating Furnace sized at 89.28 kbtu/hr using a 74.83 F EDB and a 90 F LDB. There is a heat exchanger present 0.5\0.5 Sensible\Latent. (see  218-112 Totem Base DOA SV-A attached)

The resulting 218-112 Totem Base1 PSZ Furnace,DX, No Reheat Airside HVAC Summary (see attached) shows a Heat Design Capacity of 58.0 Btu/sf. Multiply 58.0 by 3384 sf (area shown) = 196 kbtu/hr Design Capacity.

There is a big difference between 82.28 kbtu/hr  and 196 kbtu/hr. Curiously, the difference appears to be equal to the -107.03 kbtu/hr , the Zone ADDITION RATE shown in SV-A

The questions are:

  1.  What does the ADDITION RATE represent and why does it show up as ZONE HEATING value when ZONE HEATING is defined as "None"?
  2.  Why does the ADDITION RATE shown up in the Airside HVAC Summary as part to the Design Heating Capacity when the corresponding SV-A Furnace Size does not include this value?
  3.  How is the Heating Furnace Design Capacity  EDB\EWB temperature calculated? Is there a value that gets set in the input file somewhere? If so, where?
  4.  Why does the Heating Furnace Design Day Peak occur on 4/8/8 in SV-C when the LS-A (see attached) shows a maximum load date of 11/29?

These are probably questions only the eQuest staff can answer. Does anyone know how to contact them?

Kathryn Kerns
Systems Specialist
BCE Engineers, Inc.
| Ph: 253.922.0446 | Fx: 253.922.0896 |

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