Commercial HVAC systems are designed to both dehumidify and cool your building or facility while keeping an eye on crucial HVAC targets: cost-effectiveness and optimal interior temperature. An optimally maintained chiller used in the HVAC system is critical to achieving these goals.

A chiller is the HVAC component responsible for transferring heat from the internal environment to the external environment.

Heat transfer–moving heat from one space to another–always goes from hot to cold (heat never moves from a cold area to a warmer one). HVAC systems can harness this process, through vapor compression or vapor absorption, by implementing an HVAC chiller to help maintain comfortable indoor temperatures. 

A chiller alters the physical properties of the coolant to transfer heat from one place to another. Chemistry’s Gay-Lussac’s law tells us that the pressure-temperature relationship has fixed parameters. The law says if you increase the pressure on coolant, then the temperature goes up. The reverse is also true: reduce the pressure and the temperature drops. 

When coolant circulates through various parts of an HVAC chiller, its properties change:

  • As pressure changes occur, the coolant goes from a liquid to a gas state by boiling in the evaporator. It’s here the refrigerant absorbs heat, causing a temperature drop. 
  • In the compressor, the coolant is removed from the evaporator but keeps its low pressure. The compressor simultaneously raises the pressure in outgoing refrigerant vapor to release heat when it reaches the condenser. 
  • The refrigerant transitions from gas to a liquid state when it condenses, in the condenser and its heat is carried away by the cooling air or water medium.

All this happens in a seamless progression with an HVAC chiller operating at peak levels.

Air-Cooled vs. Water-Cooled Chillers

An air cooler typically funnels the refrigerant through coils with air forced over and across them by high power fans that remove heat— venting to the exterior of the building. 

A water cooler involves a second heat transfer from the refrigerant to the water. It’s sent up and circulated through a tower to remove the heat that radiates into the air above ground level.

Both types of cooling systems require maintenance to maintain operational efficiency.

Ongoing Chiller Maintenance

Maximum efficiency and cost savings can be achieved only through continuous and comprehensive chiller maintenance. This maintenance can be both preventive (regularly scheduled based on best practices) and predictive (based on sensor data from within the system, which is an early warning indicator of an impending breakdown.)

Preventive Maintenance

With preventive maintenance, you’ll be able to anticipate the following tasks as required at regular intervals (as recommended by your chiller manufacturer):

  • Inspection and cleaning of condenser coils in air-cooled systems. Coils should be clog-free allowing air to pass freely;
  • Inspection and replacement of damaged or worn fans, fan arrays, or fan components for air-cooled systems;
  • Ensure proper water flow and prevent fouling or scaling in water-cooled systems by flushing condenser water loops;
  • Water treatment–including glycol dosing–to keep water-cooled systems free from bacterial growth;
  • Leak testing will help you safeguard against refrigerant escaping from tubes and ensure that there aren’t any water leaks in water-cooled systems or air leaks in air-cooled systems.

Predictive Maintenance

Predictive maintenance can help reduce the risk of a system’s otherwise unanticipated catastrophic failure and improve efficiency by monitoring every component of the chiller from the coolers to the refrigerant tubes.

  • Monitored fan efficiency. Fans operating below optimal speeds can cause loss of efficiency for the air cooler system.
  • Monitored water usage. Increased evaporation at tower level, causing water usage to rise, is a sign of poor water cooler efficiency.
  • Monitored refrigerant levels. A proper refrigerant charge can positively impact energy efficiency by reducing cooling costs up to 5-10%.

The future of HVAC and chiller optimization hinges on the Internet of Things (IoT), which can track, analyze and report data that enables predictive preventive maintenance. Building engineers can visualize critical HVAC assets in real-time and actual operating conditions can be determined based on an analysis of total power consumption and kW/ton efficiency.  

Investing in IoT capability can be a significant advantage in chiller maintenance and extension of chiller lifespan extension. Keeping every component operating at peak performance means reducing HVAC energy consumption costs while extending the number of years between complete chiller replacements.  

Are you looking to maximize your HVAC chiller? Therma’s HVAC experts are ready to help. Get in touch today.