What is the purpose of a digital probe thermometer?

The purpose of a digital probe thermometer is primarily to measure temperature accurately in a variety of applications, including the testing of temperature rise and fan operating temperatures. This kind of thermometer is equipped with a probe that can be inserted into the area or system being measured, allowing for precise assessments of temperature conditions.

In the context of combustion appliances, monitoring temperature rise is critical for ensuring that systems are operating within safe limits and can help identify potential issues, such as overheating, that could pose hazards. Such measurements are vital for both safety and performance assessments of heating appliances.

The other choices do not align with the primary function of a digital probe thermometer. Measuring humidity levels, tracking gas pressure, and checking ventilation rates involve different tools and methods that specifically cater to those needs. Thus, the use of a digital probe thermometer is best suited for temperature-related assessments, making it an essential tool in the diagnosis and maintenance of combustion appliances.