What typically provides heating to the air in an air-water system?

In an air-water system, heating is typically provided by boilers. Boilers function by heating water, which can then be circulated through pipes to provide warmth to various environments by either utilizing radiators or hydronic systems. This method is effective for producing consistent and uniform heat throughout a space.

Heat pumps, while they can be used for heating, primarily function by transferring heat rather than generating it through combustion of fuel. They are more commonly associated with systems designed for both heating and cooling.

Centrifugal pumps are involved in the movement of fluids within a system but do not have a role in generating heat. Their purpose is strictly for circulation, not provision of heat.

Chillers, on the other hand, are designed to remove heat from a liquid via a vapor-compression or absorption refrigeration cycle, making them suitable for cooling rather than heating.

Therefore, the role of boilers in generating heat distinguishes them as the correct choice for heating in an air-water system.