When a customer's furnace stops heating on very cold nights, what is a likely issue according to the technician's assessment?

When assessing a furnace that has stopped heating on very cold nights, one likely issue could indeed be related to the heat anticipatory setting on the thermostat. The heat anticipatory setting is designed to help the system reach the desired temperature more efficiently but can lead to problems if it is not set correctly. If this setting is incorrect, the thermostat might cut off the heating system too early or not activate the furnace when it should, particularly during extremely cold conditions when the demand for heat is higher.

Having the anticipatory setting misconfigured can prevent the furnace from running long enough to adequately heat the space, leading to inadequate warmth on particularly cold nights. It is crucial for the technician to ensure the thermostat's settings are correctly adjusted to maintain optimal performance of the heating system.

In contrast, other issues such as dirty burners would likely affect heat output more broadly, and low refrigerant levels pertain to cooling systems, not heating. A faulty thermostat could also cause heating problems, but it is often the anticipatory setting that is mistakenly adjusted or misconfigured, especially in scenarios with fluctuating temperature demands.