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CHAPTER 2: Adding/Editing Heat Pumps
As can be seen from the figure, the source entering water temperature
(EWT) is listed to the left, and the capacity and power requirement of the
unit at different flow rates are listed to the right. Once the values are
input, the coefficients and flow factor can be calculated from the entered
data. The Calculate Coefficients button turns red when values are
changed, indicating that new coefficients must be calculated before
proceeding.
Note: If data for only one flow rate are available, only the first capacity
and power requirement data must be included, under the section entitled
‘FLOW RATE 1’. The data under ‘FLOW RATE 2’ can be left as
zeroes, and the program will ignore them, leaving the flow factor as 1.0.
Load Side Corrections
Corrections resulting from variations in inlet temperatures and flow rates
on the load side can be entered in the Load Temperatures and Load Flows
tabbed panels of the Pump Edit pane. If these corrections are not added,
the factors remain at 1.0 and input variations in load temperature or flow
rate will have no effect on calculated capacities and/or input power. Time
permitting, however, it is best to include as much information as possible
from what the manufacturer provides.
Load Temperatures Panel
The Loads Temperatures panel is where corrections for variations
in the load inlet temperature are input. Both the cooling and
heating information (taken at the average or standard source
temperature and flow rate, and the average load flow rate) are
entered on the same panel, an example of which is shown in figure
2.5.
The factors shown in figure 2.5 were calculated from a
manufacturer’s list of capacities provided for the different
temperatures, using the capacity at the selected temperature as the
numerator and the capacity at 67°F for cooling (70°F for heating)
as the denominator. The 67°F (70°F) capacity values were those
used for the inlet source data on the Cooling and Heating tabbed
panels described previously. Occasionally, manufacturers will
provide capacity values at the standard temperature with a table of
correction factors that can be entered into the GLD Load
Temperatures panel directly.
Notice how in figure 2.5 five points of data are included for
cooling but only three are included for heating. The software
requires a minimum of three data points for its coefficient
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