A damper assembly is configured for deployment in an existing forced air duct that supplies conditioned air through a register boot to a vent cover secured relative to the register boot. The damper assembly includes a damper frame having an at least substantially obround shaped frame periphery and a damper blade having an at least substantially obround shaped blade periphery. A damper insert arm is biased into a deployment configuration in which the damper insert arm is at least substantially perpendicular to the damper frame and is movable into an operational configuration in which the damper insert arm is at least substantially parallel with the damper frame. A latch is configured to releasably engage the damper insert arm in order to hold the damper insert arm in the deployment configuration.