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UP 15-42F/FR
Closed Systems, 60 Hz
UP 26-64F
Closed Systems, 60 Hz
SECTION III: PRE-INSTALLATION (cont.)
Figure 4:
GRUNDFOS UP 15-42F performance curve
Figure 5:
GRUNDFOS UP 26-64F performance curve
Note:
Zone valves on the heat source supply to the indirect heater are not recommended
and will drastically reduce performance.
System performance can also vary based on the heating capacity of the boiler. If the
minimum coil output (assume coil output = boiler output) listed in Tables 2 and 3 is not met,
the output (first hour rating) of the water heater will not be met at the selected flow rate.
To approximate the reduction in first hour rating as a result of low boiler capacity, use the
following formula:
New first hour rating = (First hour rating) * (Actual boiler output)/(Minimum coil output)
For example, the first hour rating of a 50SK at a 77°F rise with an 14 GPM heat source flow
rate using a boiler having a DOE heating capacity (output) of 60,000 BTU/Hr would be:
New first hour rating = (205 gal) * (60,000 BTU/Hr)/(94,000 BTU/Hr) = 131 gal
