Why does heat transfer fluid quality matter?
The condition of the heat transfer fluid in a recirculating chiller can have a significant effect on cooling performance, reliability, and equipment life.
Even when the correct fluid is initially used, its condition can change over time. Contamination, degradation, or the use of unsuitable fluid can affect both heat transfer and the components throughout the cooling circuit.
For standard ATC chillers, ATC recommends approved Hexid or CoolFlow inhibited glycol-based coolants and following the fluid requirements specified for the particular unit.
How can poor fluid quality affect a chiller?
A recirculating chiller relies on the process fluid to carry heat efficiently between the application and the chiller.
If the fluid becomes contaminated or deteriorates, deposits, and other contaminants can accumulate within the coolant circuit. This can restrict flow, reduce heat transfer performance, and place additional demands on components such as pumps and heat exchangers.
Maintaining the correct fluid condition therefore helps the complete cooling circuit to operate as intended.
What problems can develop within the cooling circuit?
Several problems can be associated with poor quality, contaminated, or unsuitable process fluid:
Corrosion
Corrosion can damage components and internal surfaces within the cooling circuit. Corrosion products can also circulate with the fluid, creating further contamination and potentially contributing to restrictions elsewhere in the system.
ATC’s approved glycol-based coolants provide corrosion protection to help protect pumps, seals, heat exchangers, and other compatible components within the cooling circuit.
Scaling and Deposits
Deposits on internal surfaces can restrict coolant passages and create a barrier to effective heat transfer.
As deposits accumulate, the chiller may be less able to transfer heat efficiently and coolant flow through the system may also be affected.
This is one of the reasons that untreated tap water, with its variable mineral and dissolved salt content, is not approved for use in standard ATC chillers.
Biological Growth
Microorganisms can develop in poorly maintained cooling systems under suitable conditions.
Biological growth can contaminate process fluid and contribute to fouling, deposits, and restrictions within the cooling circuit.
Approved inhibited coolants help to protect against biological growth as part of maintaining a reliable cooling system.
General Contamination
Contamination can enter a cooling circuit from the wider process, pipework, hoses, or during filling and maintenance.
Particles, residues, or incompatible substances circulating within the system may affect narrow passages, heat exchangers, pumps, and other components.
Good fluid management should therefore consider the complete cooling circuit, not only the fluid inside the chiller.
How does fluid quality affect cooling performance?
Effective process cooling depends on heat being transferred from the application into the process fluid and then from the fluid into the chiller’s refrigeration system.
Anything that interferes with this process can affect performance.
For example, deposits on heat transfer surfaces can reduce heat exchange, while contamination or restrictions within the circuit can affect coolant flow.
Maintaining the correct fluid in good condition helps the chiller provide consistent thermal performance while reducing unnecessary stress on components.
Why does ATC recommend inhibited heat transfer fluids?
For standard ATC chillers, ATC recommends Hexid or CoolFlow inhibited glycol-based coolants.
These approved fluids have been selected to provide:
- Corrosion protection
- Biological growth inhibition
- Reliable long-term thermal performance
- Protection of pumps, seals, and heat exchangers
Using an approved fluid is therefore about more than freeze protection. It forms part of protecting the chiller and maintaining reliable operation throughout its service life.
How can I help to maintain good fluid quality?
Always use the process fluid and concentration specified for your chiller and follow the fluid inspection and maintenance guidance provided for your equipment.
Avoid introducing contaminants when filling or maintaining the cooling circuit, and do not mix different coolants unless their compatibility has been confirmed.
If the fluid becomes visibly contaminated, changes significantly in appearance or condition, or you are unsure whether it remains suitable for use, contact ATC for advice.
What if my application requires a different fluid?
Fluids other than ATC’s approved standard inhibited coolants should not automatically be assumed to be compatible with a standard chiller.
Applications requiring DI water, oil, or another specialist heat transfer fluid should be discussed with ATC before the equipment is specified, filled, or commissioned.
Depending on the fluid and application, Engineering review and a non-standard cooling circuit specification may be required.
Where can I find more information?
See “How do I choose a heat transfer fluid?” for more information about approved process fluids, or our individual FAQs covering glycol, water, and specialist fluids.
If you have an existing chiller and are concerned about the condition or suitability of its process fluid, contact ATC with the model and serial number and details of the fluid currently in use.
