The present disclosure is directed to a system for determining scaling in a boiler. At least one sensor may monitor a boiler during operation and provide sensor data to a boiler monitoring module including a boiler scaling determination module that may determine an amount of scaling in the boiler. Example sensor data may comprise power input, a temperature of liquid in the boiler and an air temperature within an enclosure housing the boiler. The boiler monitoring module may determine thermal energy transfer to the boiler based on the liquid and enclosure temperatures. A machine learning engine may determine a rate of thermal energy transfer to the liquid in view of the power input, the rate of thermal energy transfer being evaluated by the machine learning engine to identify delay in the rate of thermal energy transfer that quantifies an amount of scaling in the boiler.