Gas Fitter Practice Test

As the outlet temperature decreases from a water heater to the heating loop, what typically happens to the heating output from the air handler?

1. Heating output from the air handler decreases

2. Heating output from the air handler increases

3. Rate of heat transfer from the water to the air increases

4. Greater temperature drop through the heating loop

The correct answer is: Heating output from the air handler decreases

As the outlet temperature decreases from a water heater to the heating loop, the heating output from the air handler typically decreases because the air handler relies on the temperature differential between the heated water and the air passing over the heat exchanger. When the temperature of the water in the heating loop drops, the ability of the air handler to transfer heat to the air is diminished, resulting in less efficient heating output. In heating systems, the effectiveness of heat transfer depends significantly on the temperature of the fluid being used. Higher temperatures allow for greater heat exchange, while lower temperatures reduce this capacity. The air handler is designed to maximize comfort by providing a certain output of warm air, and a drop in water temperature means that the energy available for heating the air is lower, leading to a decreased heating output. This understanding emphasizes the importance of maintaining an appropriate temperature in the heating loop to ensure the air handler operates efficiently and effectively in providing adequate heating to the space.