secondary pumps, another primary chilled water pump and chiller are started. A pump and chiller are shut off when flow in the common leg exceeds that of one pump, with some addi-tional margin to prevent short cycling. The load-based strategy measures system load or indirect indications of load such as return water temperature. Chillers Water leaking from a radiator valve might be seeping from around the valve spindle. However, when the water runs round and drips from the valve's cap-nut, it's the nut that often appears to be the source of the leak. Dry the valve then hold a fresh piece of paper tissue against the various bits to work out exactly where the moisture is coming from.
Ball valves are durable and typically work to achieve perfect shutoff, even after years of use. For this reason, ball valves are the preferred choice for shutoff applications. Hydrovalve gas ball valves have female threaded (IPS) connections and are available in 1/2", 3/4", and 1" sizes.