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

[Kathryn Kerns]

From: Kathryn Kerns
Sent: Monday, September 23, 2019 1:10 PM
To: Equest-users <equest-users-bounces at lists.onebuilding.org>
Cc: Joshua Wood <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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