Centrifugal Pump Selection for Hydronic Systems (Part 1)

Norm Hall
October 11, 2010
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You’ve selected the GPM (gallons per minute) flow rate and the pump head. You corrected the head for the fluid as described in the last few articles. It’s time to select a water pump. Why do you select one pump over another and how do you, as the specifying engineer, make sure the submitted pump is remotely close to the one you selected. The R. L. Deppmann Monday Morning Minutes looks at this starting today.

Before looking at pump curves let’s decide what type of pump to use. Should it be inline, end suction, base mounted, close coupled, flexibly coupled double suction, vertical turbine, or any number of other types. Often this decision is made for you through office standards but let’s review the advantages of each.


B&G Series 100 3-piece circulator B&G Series PL Close Coupled Circulator
B&G Series 100 3-piece circulator B&G Series PL Close Coupled Circulator


ITT Bell and Gossett (B&G) inline pumps come in a variety of sizes and construction. Very small inline pumps similar to ones used is residential applications are great for AHU coils and low flow secondary pumps. These pumps are available in the “tried and true” three piece circulator style or close coupled NRF or PL style. The issue we often find with the 3-piece circulator is the oil lubricated bearings. These bearings provide quiet reliable service but require maintenance. Many of your clients prefer maintenance free circulators so we suggest the NRF and PL pumps for small applications.

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I would recommend you select the B&G PL or NRF wet rotor pumps for those small low head heating and cooling applications under ½ HP. These loads are low enough for these pumps to provide years of trouble free operation without the cost of larger inline pump construction. Next week we will provide information about the larger inline pumps. Click HERE to have a sales engineer contact you for update suggestions to your pump specifications.

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Disclaimer: R. L. Deppmann and it’s affiliates can not be held liable for issues caused by use of the information on this page. While the information comes from many years of experience and can be a valuable tool, it may not take into account special circumstances in your system and we therefore can not take responsibility for actions that result from this information. Please feel free to contact us if you do have any questions.