Rheem Indirect Water Heater - Manual (Page 8)

Page 8
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
NOTICE: Zone valves on the heat source supply to the indirect water 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 indirect 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 STID50 at a 77°F rise with an 8 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 = (160 gal) * (60,000 BTU/Hr)/(77,000 BTU/Hr) = 125 gal