NATE Air Conditioning and Heat Pumps Practice Exam

What is the typical water flow rate per ton of cooling for water-source heat pumps operating in closed-loop systems?

1. 3.0 gpm per ton

2. 2.5 gpm per ton

3. 2.0 gpm per ton

4. 1.5 gpm per ton

The correct answer is: 3.0 gpm per ton

The typical water flow rate for water-source heat pumps operating in closed-loop systems is approximately 3.0 gallons per minute per ton of cooling. This flow rate is based on ensuring that the heat pump can effectively exchange heat with the water circulating through the system. In closed-loop systems, the water must be able to absorb and release sufficient heat to meet the heating and cooling demands of the space being conditioned. The 3.0 gpm per ton flow rate ensures that there is adequate thermal transfer, enabling efficient operation of the heat pump. This flow rate helps maintain the right temperature differential and pressure conditions for optimal performance, ensuring that the system runs efficiently and effectively. Lower flow rates, such as 2.5 gpm or 2.0 gpm, may not provide enough thermal transfer capacity, potentially leading to inefficiencies and insufficient heating and cooling performance. Similarly, excessively low flow rates like 1.5 gpm could cause operational issues, including reduced heat exchange efficiency and potential freezing in the hydronic circuits in colder climates. Thus, 3.0 gpm per ton is recognized as the standard to ensure reliable and efficient system performance in these applications.