If a furnace's temperature rise should be between 35-65˚F but it is only reaching 20˚F, what adjustment may be necessary?

In a situation where a furnace's temperature rise is significantly below the acceptable range of 35-65˚F and is only reaching 20˚F, adjusting the indoor blower speed can be crucial. When the blower speed is decreased, it allows the air to remain in the heat exchanger longer, giving the air more time to absorb heat. This can lead to a more effective increase in temperature, enhancing the overall heating efficiency of the system.

If the blower speed is too high, it can cause the air to move through the heat exchanger too quickly, which may prevent the air from gaining sufficient heat before being distributed into the home. Thus, reducing the blower speed helps ensure that air has adequate contact time with the heat exchanger, optimizing the temperature rise and aligning it more closely with the necessary range.

While other adjustments, such as cleaning the heat exchanger or replacing the thermostat, might be important in different contexts, in this case, focusing on the blower speed directly addresses the issue of achieving an adequate temperature rise effectively.