The Bell & Gossett ZoneTrol II AZ-1A snap-on relay box is an easy to install single zone pump controller that mounts directly on any Bell & Gossett wet rotor circulator or Series PL booster. The Add-A-Zone turns the pump and boiler ON when the thermostat calls for heat.
Using the wire nuts provided with the package, the AZ-1A is quickly assembled onto any NRF/NBF or 1/12 to 1/6 HP Series PL. The clearly marked terminals for the thermostat and the isolated end switch terminals make the rest of the hook-up a snap. The AZ-1A can be daisy-chained together to control multiple zones. The Bell & Gossett AZ-1A is ideal when adding a zone to an existing system.