Understanding Primary Secondary Pumping Part 6: 5 Ways to Pump an HVAC System

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By Chris Edmondson

There’s more than one way to pump a chiller or boiler system.  In fact, there are five common approaches, and all but one includes some variation of our topic of late -- primary secondary pumping. 

Variable Primary Pumping

Contemporary systems that do not utilize primary secondary pumping are typically known as variable primary systems.  In this simple design, there is only one set of pumps (chiller or boiler pumps) creating flow for the entire system. 

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Understanding Primary Secondary Pumping Part 5: Best Practices for Piping

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By Chris Edmondson

Piping in a primary secondary pumping systems as a whole can be quite complex, but when it comes to the “primary” part of the system, there are really only two approaches:  Dedicated or Non-dedicated.

Figure 1 shows the chillers in a primary secondary system piped with one pump per chiller.  If the chillers

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Understanding Primary Secondary Pumping Part 4: “What happens when...?”

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By Chris Edmondson

Now that we know what happens when we vary flows and mix temperatures in a primary secondary pumping system, let’s explore these theories in some more realistic scenarios. 

As discussed in a previous blogs, when it comes to primary secondary systems, one of three flow patterns is always in occurrence: 

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Understanding Primary Secondary Pumping Part 2: Mixing Temperatures (and Flows!) in a Hydronic System

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By Chris Edmondson

What happens in a pipe when water of two different temperatures (and perhaps different flow rates) merge? 

There’s a pretty straightforward formula that tells you exactly what the resultant water temperature will be. In this blog, we’ll go over that calculation, as well as take a closer look at how blended temperatures

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Understanding Primary Secondary Pumping Part 1: Behold the Humble Tee!

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Are you involved in the design or installation of hydronic systems?  Do you anticipate becoming involved?

 If you answered yes to either of these questions, this blog series on primary/secondary pumping will interest you.  If you are a hydronic’s veteran, feel free to skip the first few blogs in the series – they may be too much of a review.  Better yet, pass them onto a junior associate and

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