Thoroughly drain using valves at the system's low points. As the fluid drains, it's best to observe what comes out. If you see chunks of carbon and other solids, you should consider flushing with the heat transfer fluid you intend to use. Call us for additional information. We suggest that you consider cleaners other than water-based types.
Water is difficult to remove, and can itself cause corrosion.
Charging Your System Connect a small positive displacement pump to a system low-point valve. A convenient place to fill is through the blow-down valve which is many times located on the strainer. The strainer is usually located upstream of pump suction. Bottom-filling can substantially reduce the entrainment of air, a common cause of both pump cavitation and fluid oxidation. And, bottom-filling allows the system to vent normally as the fluid enters.