[BLDG-SIM] eQUEST v.3.6 - Hot Water Loop Heating Capacity Different from Plant Size

[Mark Nieman]

Hello all, I am simulating an H-shaped, 13 story, 600,000 square foot,
50+ year old office building in Seattle, WA with the core zones served
by a dual-duct system and the perimeter zones served by a 4-pipe fan
coil system. The systems run 24 hours a day with no setback. eQUEST
reports an air handler summary heating design load of 39.6 Btuh/sf which
appears within reason for this type of setup.

My concern is the discrepancy between Hot Water Loop Heating Capacity in
the PV-A report vs. the Hot Water Loop Peak Net Load in the PS-D report.
The PV-A Circulation Loop Heating Capacity number is -23.700 MBTU/HR,
which corresponds with the 39.6 Btuh/sf reported under the Air-Side HVAC
Summary sheet. In the PS-D report, the Hot Water Loop Peak Net Load is
-8774.2 KBTU/HR, which is 37% of the value in PV-A. The PS-C, Equipment
Loads and Energy Use report also agrees with PS-D, showing the boiler
peak Heat Load at -8774.2 KBTU/HR, with hours of operation showing up in
all part load ranges, totaling 8,595 hours of operation per year (due to
the reheat system and 24 hour operation).

Am I understanding correctly that the -23.7 MBTU/HR is a peak connected
load (sum of the air handler/zone heating coils), but that the hot water
boiler plant will see only a peak of -8774.2 KBTU/HR because of
diversity? Any insight would be much appreciate.

Mark Nieman, PE, CEM
Sr. Energy Engineer
McKinstry Essention
Direct: (206) 832-8152
Cell: (206) 510-4760
FAX: (206) 832-8552
http://www.mckinstry.com
"For The Life Of Your Building"



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