Miles Ryan, a P.E. at QSEng authored this ASHRAE article published in February 2021. Most readers familiar with the operation of HVAC systems are aware of the term closed-loop control, oftentimes referred to as just a control loop, closed-loop, or feedback loop. Additionally, many will describe them as PID loops, short for Proportional-Integral-Derivative loops, although…

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Synopsis There are numerous parallels and striking differences between domestic hot water recirculating systems, and the hydronic systems used to heat and cool facilities. This paper will explore those parallels and differences to highlight the common pitfalls seen in the design and operation of domestic hot water recirculating systems which include the presence of a…

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