Choose the right heat transfer fluid and check it regularly

      Literature and assistance is available from fluid suppliers to ensure the chosen fluid is appropriate for the system operating conditions. A representative fluid sample should be taken, typically once a year, and sent to the manufacturer for analysis. Sampling kits are available. The results may show anomalies of the fluid properties, such as oxidation, carbonization, viscosity increase etc that can indicate specific system problems, and will eventually indicate when the fluid should be changed. If the fluid is left in the system too long heat transfer efficiency will be reduced and components such as pumps and control valves can be damaged by particulate build up. If particulates are present, they can be removed by the use of a sidestream filter. If additional fluid is required due to replacement or to make up losses, it should be pumped in to the system at a low point(s) (see diagram), not added to the expansion tank. Filling the system from the low point(s) allows air to be naturally vented.