There are only a couple of types of these systems.

A plumbed return system piped from each fixture with a timed pump at the water heater.

And those that connect and are installed at the farthest or each fixture.

Not enough information. Did they have to run a new return line? Did they have to pull power to the pump? Are there other controls in the system? BTW, the very best recirc system is the Metlund design unit. www.gothotwater.com