What is a common cause of metering inaccuracies linked to fluid characteristics?

Fluid viscosity and density changes are significant factors that can lead to metering inaccuracies in HVAC systems. Metering devices are designed to measure fluid flow based on certain assumptions about the properties of that fluid. When the viscosity of a fluid changes, it can affect how easily the fluid flows through the metering device, altering the readings and leading to inaccuracies. Similarly, changes in fluid density can also impact the measurement. For instance, a denser fluid may require different calibration of the metering device compared to a less dense fluid. These variations can occur due to temperature changes, impurities in the fluid, or other operational conditions.

In contrast, while factors like the type of pump, the length of ductwork, and the age of the system can impact overall system performance, they are not directly linked to the inherent characteristics of the fluid itself that affect metering accuracy. The type of pump may influence flow rates, but it does not directly cause the inaccuracies linked to fluid properties. The same goes for the length of ductwork and the age of the system, which deal more with system design and maintenance than with how the fluid's properties affect measurements.