Gas Fitter Practice Test

Which component controls the flow rate of water through a heating coil of an air handler?

1. Aquastat on the water heater

2. Balancing valve on the heating loop

3. Mixing valve on the heating loop

4. Mixing valve on the domestic hot water system

The correct answer is: Balancing valve on the heating loop

The component that controls the flow rate of water through a heating coil of an air handler is the balancing valve on the heating loop. This type of valve is specifically designed to regulate the flow of water, ensuring that the system operates efficiently and effectively. By adjusting the balancing valve, a technician can fine-tune the flow rate, which is crucial for maintaining the proper temperature and performance of the heating coil. This is particularly important in systems that distribute hot water to multiple locations, as it allows for even heating and optimal performance. In contrast, the other options don't serve the same function regarding flow rate control in the air handler context. An aquastat on the water heater is more focused on regulating the temperature within the water heater system rather than directly managing the flow in the air handler. A mixing valve on the heating loop allows for temperature adjustments by mixing hot and cold water but does not directly regulate flow. Lastly, a mixing valve on the domestic hot water system serves to blend temperatures for safe water delivery in residential uses, rather than controlling the flow specifically within the air handler's heating coil.