______ draft is produced by a fan located between the boiler and the chimney:

Induced draft is produced by a fan that operates in a position between the boiler and the chimney, which helps to draw flue gases from the boiler and into the chimney. This arrangement operates on the principal of removing the combustion gases, enhancing the flow through the heating surfaces of the boiler and ensuring efficient combustion by maintaining the correct airflow.

The induced draft system creates a slight vacuum in the furnace area, which helps to pull the combustion air into the boiler and push the gases out through the chimney. This method is particularly beneficial as it allows for better control of the combustion process and minimizes the risk of flue gas leakage into the boiler room.

In contrast, natural draft relies on temperature differences and buoyancy to move gases without any mechanical assistance, while forced draft utilizes a fan positioned at the inlet of the furnace to blow air into it. Negative draft typically indicates a situation where the draft is insufficient or excessive pressure conditions exist, which is not specifically the case here with an induced draft system.