Hello All,
My first post to bldg-sim, I have learned a great deal from your emails.
I am trying to wrap up an eQuest model of a school that is using water
source heat pumps (located in Georgia). The building is connecting to a
campus condenser water loop, so there is no heat rejection system that is
actually part of the project, but I have to include something in eQuest,
which I have modeled as a cooling tower and variable speed pump.
I am running in to issues with no heating or cooling energy being reported
in the BEPS report, and 94% of hours outside throttling range. I have tried
several different types of HVAC systems (pkgd single zone, water loop HP,
pkgd var vol var temp) all with condenser type as ?water cooled? (except for
water loop hp which doesn?t allow you to pick a condenser type). I have set
my circulation loop for condenser water to loop type ?condenser water? and
also tried loop type ?Water Loop HP? which no success. When I use ?Water
Loop HP? I get an error message ?Loop: WLHP water loop has no primary
heating equipment.?
On my HVAC systems ?heating ? coil capacity? display I have heat source set
to ?heat pump? and zone heat source as ?not installed?
Any ideas? A bad combination of system type and heat rejection maybe? I
have tried all combinations that I can think of.
Thanks for taking a look,
Mike Gutowski, PE
Hello Mike,
Whenever we need to add water source heat pumps to a project, we import
this .inp file code snippet:
$ *********************************************************
$ ** **
$ ** HVAC Circulation Loops / Plant Equipment **
$ ** **
$ *********************************************************
$ ---------------------------------------------------------
$ Pumps
$ ---------------------------------------------------------
"WLHP Loop Pump" = PUMP
NUMBER = 1
MOTOR-CLASS = HI-EFF
..
"WLHP Blr (HWNatDrft) Pump" = PUMP
MOTOR-CLASS = HI-EFF
..
$ ---------------------------------------------------------
$ Circulation Loops
$ ---------------------------------------------------------
"WLHP Water Loop" = CIRCULATION-LOOP
TYPE = WLHP
LOOP-OPERATION = STANDBY
DESIGN-HEAT-T = 70
DESIGN-COOL-T = 85
COOL-SETPT-CTRL = FIXED
LOOP-PUMP = "WLHP Loop Pump"
..
$ ---------------------------------------------------------
$ Boilers
$ ---------------------------------------------------------
"WLHP Blr (HWNatDrft)" = BOILER
TYPE = HW-BOILER
HEAT-INPUT-RATIO = 1.25
HW-LOOP = "WLHP Water Loop"
HW-PUMP = "WLHP Blr (HWNatDrft) Pump"
..
$ ---------------------------------------------------------
$ Heat Rejection
$ ---------------------------------------------------------
"WLHP Fluid Cooler" = HEAT-REJECTION
TYPE = FLUID-COOLER
CAPACITY-CTRL = ONE-SPEED-FAN
CW-LOOP = "WLHP Water Loop"
..
If you already have heat pump plant equipment defined, it may require
cutting (existing) and pasting (new) equipment directly from your .inp
file -- be sure of course to make a backup. Is the campus he rejection
loop ultimately air cooled or ground source? If air cooled then the
fluid cooler heat rejection should be reasonable. If ground source, try
this code snippet instead for starters:
$ *********************************************************
$ ** **
$ ** HVAC Circulation Loops / Plant Equipment **
$ ** **
$ *********************************************************
$ ---------------------------------------------------------
$ Pumps
$ ---------------------------------------------------------
"GSHP Loop Pump" = PUMP
NUMBER = 1
MOTOR-CLASS = HI-EFF
..
$ ---------------------------------------------------------
$ Circulation Loops
$ ---------------------------------------------------------
"GSHP Water Loop" = CIRCULATION-LOOP
TYPE = WLHP
LOOP-OPERATION = SUBHOUR-DEMAND
DESIGN-HEAT-T = 30
DESIGN-COOL-T = 110
COOL-SETPT-CTRL = FIXED
MAX-ALARM-T = 110
MIN-ALARM-T = 30
LOOP-PUMP = "GSHP Loop Pump"
..
$ ---------------------------------------------------------
$ Ground Loop Heat Exchangers
$ ---------------------------------------------------------
"GLHX (VertWell-CM)" = GROUND-LOOP-HX
TYPE = VERT-WELL-NEW
CONFIGURATION = "Rectangle-3x5"
DEPTH = 200
SPACING = 20
PIPE-OUTSIDE-DIA = 1.05
PIPE-INSIDE-DIA = 0.859
U-TUBE-LEG-SEP = 3.9
PIPE-COND = 0.23
FIELD-MULTIPLIER = 1
GRND-DIFFUSIVITY = 0.0432208
GRND-COND = 1.68
NUM-OF-YEARS = 0
GROUT-COND = 0.85
BOREHOLE-DIAM = 6
REF-GRND-ADJ = 5
FLUID = WATER
CIRCULATION-LOOP = "GSHP Water Loop"
..
Hope that helps...if not, verify your schedules against a known good
project. Personally I change at the auto-generated schedules whenever
possible, here's a couple of posts on how to do that:
http://elcca-exchange.blogspot.com/search/label/Schedules
Brandon Nichols, PE, LEED(r) AP