Currently we have flow switches with a single pole double throw (Common, Normally Open, and Normally Closed). The ddc panel is wired to common and n/c. The fan on light is wired between common and n/o. I would like to replace these flow switches with a current switch that has a sigle pole double throw. I know I can use a relay with a single pole single throw current switch to accomplish the same goal. Just wondering if any company makes a sigle pole double throw current switch?