During furnace operations, the new furnace quickly satisfies the thermostat demand. What does this indicate?

When a new furnace quickly satisfies the thermostat demand, it indicates that the furnace heating capacity is oversized. An oversized furnace produces heat at a rate that exceeds the heating requirements of the space it is meant to serve. As a result, it can reach the thermostat setting rapidly, often leading to short cycling, where the furnace turns on and off frequently. This can cause discomfort due to fluctuations in temperature, and it may lead to inefficiencies in energy use and increased wear on the system over time.

Conversely, a system functioning normally would typically maintain a balance where the furnace runs for a sufficient amount of time to heat the space without overshooting the thermostat's set point. If a furnace is undersized, it would struggle to meet the thermostat demand, taking longer to reach the desired temperature. A malfunctioning thermostat may fail to accurately relay the temperature needs, which wouldn't necessarily indicate an excess capacity of the heating system. Therefore, recognizing that the quick response time is a sign of oversized capacity helps in understanding furnace performance and efficiency.