Where is an economizer typically located?

An economizer is typically located between the boiler and the stack. This positioning allows the economizer to recover waste heat from the flue gases that exit the boiler before they are released into the atmosphere. By capturing this residual heat, the economizer preheats the water entering the boiler, which improves the overall efficiency of the system. This process increases the temperature of the water before it enters the boiler, reducing the amount of fuel needed to achieve the desired steam or hot water temperature, ultimately leading to energy savings and reduced operating costs.

The other locations provided do not serve the same function. Placing the economizer inside the boiler itself would not be practical, as it cannot effectively capture waste heat from the flue gases. The water inlet is not an ideal location for an economizer since it needs to interact with flue gases to function correctly. Similarly, positioning it near the main gas valve wouldn't allow for the optimal heat exchange necessary for its purpose.