Installing isolating valves at appropriate points in the water circuit can assist in the maintenance and repair of a chilled water system. Isolating valves can eliminate the necessity to drain the whole system to carry out certain maintenance tasks.

It is important to note the following:

• Isolating valves should not be used to regulate water flow

Gate, butterfly and ball valves are commonly used for isolating purposes.

The flow regulating valves serve several critical purposes in the water circuit. These would include the following:

• Control the flow to the process
• Balance the flow through the bypass
• Ensures the pump is running on its optimum performance curve

Flow regulating valve options commonly employed are the gate valve and double regulating valve

Gate Valve

The gate valve offers a budget option for systems with a pipe diameter up to 1.5” (38mm). The drawback with the gate valve relates to operating noise and limited accuracy of flow control.

Double Regulating Valve

A more precise option would be a double regulating valve. This type of valve offers linear adjustment across the full flow range.

The installation of water pressure gauges in the cooling circuit can provide a low-cost option to assist with the following:

• Set-up and balance of system flow. This is of importance when the flow is being split to multiple applications or when multiple chillers are installed.
• Provides an easy and quick means to visually check the flow in an operating system. Unexpected pressure changes or low / high readings can indicate a potential system issue.

The photograph below demonstrates how pressure gauges can assist in the set-up of appropriate flow to multiple points of use.

It is considered good practice to install filtration into the water circuit to protect both the chiller and process. Contamination can enter the water circuit through many routes. Poor maintenance, no flushing procedure, use of dirty water or low-grade glycol and a polluting process are examples of how the system can be contaminated.

A water filter is commonly installed at the inlet to the process. The most common types of filter used in a water circuit are as follows:

CARTRIDGE

BASKET

STRAINER

The type of filter selected for any water circuit is generally determined by the following factors:

• Diameter of the piping
• Pipework material
• Degree of filtration required (are potential contamination levels in the process expected to be high)

Installation of non-return valves are often employed in systems where multiple chillers feed a common header or ring main. In these instances, flow around the water circuit needs to be carefully managed. The non-return valves prevents back flow of water to the chiller and assists with overall system balancing.

A manual bypass should be installed when the flow rate required by the process is lower than the nominal flow rate of the chiller pump. The excess flow is diverted through the bypass by adjustment of the flow regulating valves. The manual bypass is critical to ensure reliable operation of the process and chiller.