How Dirt and Air Separators Can Improve Chiller Efficiency in Your Building and Reduce Maintenance Costs

HVAC dirt air separator

Source: Spirotherm (www.spirotherm.com)

Your chiller is a piece of equipment that significantly impacts energy consumption. An efficient and well-maintained chiller can still be responsible for about 25% of your energy costs, and each degree of efficiency that you lose can make your costs grow up to 3%.

This is why having a chiller functioning intelligently is crucial.

Your chiller is part of a closed loop system, so when analyzing its performance you should look at the entire integrated system. You probably already have a VFD or a variable speed pumping unit that models equipment and system behavior, monitors actual system conditions, and dynamically adjusts equipment operation to match your system demand.

However, if you have dirt and air running into your hydronic system, it can affect the chiller performance considerably.

Even in a system that is manually vented, dissolved air is present because no hydronic system is airtight. As the system operates, water constantly evaporates through valve stem packing, gaskets, mechanical seals, tiny fissures in the pipes and fittings, and other places. You may not notice the leaks, but you will see the build-up of mineral deposits on valve stems and gaskets. During maintenance or repair, system water will be lost and replaced by fresh water. Fresh water means more air, resulting in more problems. Do these sound familiar?

  • Annoying noises throughout the system
  • Insufficient heat or poor cooling
  • Chiller corrosion damage
  • Circulator cavitation
  • Reduced pump head, water flow, and heat transfer
  • Increased scaling throughout the system
  • Increased maintenance costs
  • Premature equipment failure

Air elimination is more important in a chilled-water system than in a hot-water system, because cold water holds more air. Without an air-separator, the constant air-water mixture being pumped will dramatically decrease heat transfer capabilities because air acts as an insulator.

In addition, oxygen causes contamination. Air in a hydronic system contains oxygen, which causes corrosion and contaminates the system. System debris can damage circulator impellers, bearings, seals, valve mechanisms and controls, not to mention that the debris contribute to blockages, consequently interfering in flow, pressure, and temperature.

HVAC dirt air separatorThe dirt separator creates a low-velocity area that forces the dirt particles to be separated and collected by a dirt trap. It is more than a filter because the dirt is collected away from the flow, not creating a barrier or dropping the pressure.

Installing dirt and air separators offers numerous benefits:

  • 100% elimination of all free and entrained air
  • Absorption of air pockets throughout system that impede heat transfer
  • Elimination of air-related “routine” maintenance
  • Cost effective full flow dirt and sediment removal
  • Boost chiller output
  • Improvement of Delta T (temperature difference)
  • Energy savings considerations

Also, dirt and air separators are ideal for retro-commissioning projects. Manual venting, bleeding, and purging are no longer necessary, once they have the ability to reduce if not completely eliminate these problems. As systems are retrofitted and re-commissioned, air elimination and dirt separation are of prime importance.