Which of the following is NOT a boiler component?

A condensing unit is typically associated with air conditioning and refrigeration systems, where it is used to condense refrigerant vapor into liquid form. In contrast, a boiler primarily consists of components that facilitate the combustion of fuel and the generation of steam or hot water.

Burners are essential to boilers as they provide the necessary fuel-air mix for combustion. Heat exchangers are vital in boilers for transferring heat from the combustion process to the water or steam being heated. Blowers, especially forced draft blowers, are used to supply air to the burner for efficient combustion.

Understanding the roles of each component highlights how the condensing unit does not fit within the typical components found in a boiler system, thereby making it the correct answer.