Rheem Indirect Water Heater User Manual
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SECTION III: PRE-INSTALLATION
boIler and CIrCulaTor sIzIng
The ratings published in this manual for your Rheem indirect water heater can be obtained
through proper selection of boiler output and circulator capacity. As noted, the ratings in Table 2
are based on a 77°F rise with 58°F potable water inlet temperature at a circulator pump flow rate
of 8 GPM. The boiler was set at 180°F. See Table 3 for additional first hour ratings at pump flow
rates of 6, 8, 10 and 12 GPM with 180°F and 200°F boiler water.
To determine the appropriate circulator for your system, follow these three steps:
1) Calculate the pressure drop of all straight pipe and fittings on the supply and return at the
desired flow rate.
2) Add the pressure drop from Step 1 to the pressure drop through the indirect water heater coil
(see Table 2 for friction loss) to obtain a total pressure drop.
3) Select a circulator pump that will provide adequate flow at the total pressure drop.
A pump performance curve should accompany every circulator pump. Figures 3-5 contain
performance curves for Taco and Grundfos circulator pumps, recommended by Rheem.
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Figure 3: Taco 00 Series performance curves