HOT AND CHILLED WATER SYSTEMS

Hot and chilled water systems are by definition "closed." They deliver hot or chilled water to heat exchangers or HVAC coils without evaporation. With no evaporation or steam production, no make-up water is introduced – the system is "closed" to make-up.

• Corrosion

  Because hot and chilled water systems typically take on little or no make-up water the primary treatment concern is corrosion. Corrosion in any system will shorten the life of expensive capital assets and cause potentially costly plant operation interruptions or shutdowns.

  Corrosion is caused by addition of oxygen into the system with make-up or by bacteria (anaerobic) allowed to flourish under existing deposits. Corrosion will also occur when the pH of the system is too low or too high. A common contributor to low pH in chilled water systems is the degradation of glycol compounds used for freeze protection.

• Scale

  Hot and chilled water systems should be "closed" to make-up addition, but if there are water losses due to leaks or draining of the system, scale-forming minerals (calcium and bicarbonate) are introduced into the system and need to be accounted for before deposition takes place. Scale formation can significantly affect heat transfer that increases operating costs and can also contribute to operation interruptions or shutdowns.

• Cleaning

  New systems should be chemically cleaned prior to startup to remove oils, greases and other contaminants that naturally enter the system during construction. Systems that have become fouled or are currently experiencing corrosion may also need to be chemically cleaned.

  • Chemical Cleaners

• Side Stream Filtration

  The only sure way to remove suspended solids is through side stream filtration. Even if a system is cleaned, side stream filtration is an excellent insurance policy to prevent potential damage caused by suspended solids (debris).

  • Filter Vessels & Cartirdges

• Corrosion Inhibitors

  It is a simple matter to prevent corrosion in hot and chilled water systems through the proper application of corrosion inhibitors. It is a one-time expense – additional material is typically only needed if water is lost from the system.

  • Closed System Treatment Chemicals

• Corrosion Control Monitoring

  The most effective way to insure that your corrosion control program is effectively protecting valuable assets is to measure the corrosion rates of the various metals in the system (most commonly iron and copper). This is done through the installation of corrosion coupon racks that hold coupons of whatever metal is of interest. The coupons are analyzed as part of our analytical services for our customers.

  • Corrosion Coupon Racks
  • Analytical Services and Products

• Freeze Protection

  Many chilled water closed systems require freeze protection when coils and other equipment are exposed to the outdoor air temperatures of northern climates. Ethylene or propylene glycols are typically used. These are not corrosion inhibitors but may be necessary to protect plant assets from failure due to freezing.

  Entire systems may contain glycol, or only coils exposed to harsh wintertime conditions. When coil layup is the approach, it is important to thoroughly flush the glycol before resuming system operation to prevent the glycol from degrading to glycolic acid, which can lower system pH and accelerate corrosion.

  Anti-freeze solutions are also available that do not contain ethylene or propylene glycol. Your H-O-H Water Technology representative should be consulted for the best recommendation.

  • Heat Exchange Fluids (Anti-Freeze Formulations)