Chilled Water Systems
When the tubes inside the Chilled Water Condenser (heat exchanger) are fouled (scale or bio-film), it is the equivalent of insulating the heat exchange tubing. This means fewer BTUs can be absorbed by the refrigerant during the evaporation cycle, which in turn delivers fewer BTUs to the condenser for transfer to the condenser water (cooling tower water), ultimately resulting in lower total BTU rejection by the system. A poorly maintained tower can reduce chiller efficiency so that annual electric costs can increase by as much as $46/ton ($23,000 increase for a 500 ton system).
Fire tube Boilers
Boilers suffer a similar fate to that of condensers. As they become scaled they require more energy or fuel to maintain the intended transfer of heat as before the scaling had occurred. This is proven by seeing higher stack temperatures. The less heat from the boiler fire that passes through the tube wall into the water, the more heat that escapes out through the last tube pass and into the stack. This causes higher maintenance costs, unexpected shut downs and premature equipment replacement costs.
Ammonia Refrigeration Systems
When the condenser in an Ammonia system becomes fouled, the system becomes its own worst enemy. The reduced flow of cool ammonia gas through the inter-cooler insures that the approach temperature and pressure of the ammonia liquid supplied to the evaporator will continue to rise. As a result, the BTU collection in the evaporator is reduced and the electrical cost of compression increases.