[BLDG-SIM] eQUEST Condensing Boiler Curve

[Mark Nieman]

Using eQUEST v.3.6, I've taken a stab at creating a performance curve
for an Aerco KC1000 condensing boiler. I've defined BOILER:HIR-FT =
"Aerco-KC1000-HIR-fEWT&LWT" as shown below. This boiler is being used
for a water source heat pump condenser water loop with a CT/HX & two
condensing boilers, piped in a primary loop configuration.

"Aerco-KC1000-HIR-fEWT&LWT" = CURVE-FIT       
   TYPE             = BI-QUADRATIC-T
   INPUT-TYPE       = DATA
   INDEPENDENT-1    = ( 180, 180, 180, 80, 80, 80, 100, 100, 100, 120,
120, 
         120, 140, 140, 140, 160, 160, 160 )
   INDEPENDENT-2    = ( 180, 90, 135, 90, 135, 180, 90, 135, 180, 90,
135, 
         180, 90, 135, 180, 90, 135, 180 )
   DEPENDENT        = ( 1, 1.023, 1.019, 1.151, 1.077, 1.065, 1.102,
1.047, 
         1.038, 1.053, 1.026, 1.017, 1.033, 1.017, 1.012, 1.023, 1.017, 
         1.007 )
   ..

Question: Is this a proper curve for this equipment? Any comments and
critiques would be much appreciated. Part of my difficulty is that
HIR-FT is a Bi-Quadratic-T or Bi-Linear-T curve that needs two
temperatures (EWT & LWT) to define the HIR ratio modifier. When looking
at the curves, it's stated as thermal efficiency vs. EWT (return water
temperature) on several different curves based on fire rate of the
boiler. Basically, I assumed a LWT based on firing rate (90F=25%,
135F=75% & 180F=100%). I'm not sure if this is reasonable or not. Per
the manual, the DEPENDENT variable is the ratio of the actual efficiency
(based on the curves) / rated efficiency (at full fire, full load).
INDEPENDENT-1 = EWT, INDEPENDENT-2 = LWT.

The link to the data sheet is here:
http://www.aerco.com/cgi-bin/docsserv.cgi?idDocument=344

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
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