Refrigerated merchandiser with glass door heat control

1. A method of operating a refrigerated merchandiser including a case defining a product display area, and at least one door providing access to the product display area, the method comprising:

sensing a parameter of an ambient environment adjacent the case;

determining a duty cycle using a controller based on the signal indicative of the sensed parameter;

detecting an occurrence of a door event of the door in response to moving the door between a first position and a second position different from the first position;

interrupting the duty cycle by initiating a clearing interval using the controller in response to the door event; and

clearing condensation from the door during the clearing interval.

2. The method of claim 1 , further comprising

sensing the door in the first position;

delivering a first signal indicative of the door position to a controller;

sensing the door in the second position; and

delivering a second signal indicative of the door in the second position to the controller.

3. The method of claim 2 , further comprising

subsequently sensing the door in the first position;

determining an end of the door event in response to sensing the door in the first position; and

initiating the clearing interval at the end of the door event.

4. The method of claim 2 , further comprising

operating the duty cycle in an “on” state for a first predetermined time;

clearing condensation from the door during the first predetermined time by applying heat to the door; and

operating the duty cycle in an “off” state for a second predetermined time.

5. The method of claim 2 , further comprising restarting the duty cycle after the clearing interval is complete.

6. A refrigerated merchandiser comprising:

a case defining a product display area and including a casing having at least one mullion defining an opening in communication with the product display area;

at least one door coupled to the casing to provide access to the product display area and to substantially enclose the product display area, the at least one door including a glass member having a conductive film;

at least one sensor positioned adjacent the at least one door, the sensor in communication with the opening to detect a door event of the door in response to moving the door between a first position and a second position different from the first position and to generate a signal indicative of the door event; and

a controller in communication with the at least one sensor to receive a signal indicative of the door event from the sensor, the controller further in communication with the conductive film to initiate a clearing interval to clear condensation from the at least one door in response to the signal indicative of the door event, the clearing interval defined by a predetermined period of time such that the clearing interval has an “on” state during which heat is applied to the door and an “off” state during which no heat is applied to the door.

7. The refrigerated merchandiser of claim 6 , wherein the sensor includes a door switch sensor, and wherein the door event includes movement of the door between an open position and a closed position.

8. The refrigerated merchandiser of claim 7 , further comprising a refrigeration system coupled to the case and in communication with the product display area to deliver refrigerated air to the product display area, and wherein the sensor is in communication with the refrigerated air in response to the movement of the door from the closed position to the open position.

9. The refrigerated merchandiser of claim 6 , wherein the sensor includes an environment sensor in communication with an ambient environment adjacent the case to sense one or more ambient conditions adjacent the door and to generate one or more signals indicative of the ambient conditions to the controller.

10. The refrigerated merchandiser of claim 9 , wherein the door event is based on the ambient conditions sensed by the sensor.

11. The refrigerated merchandiser of claim 9 , wherein the controller is programmed to determine a duty cycle having an “on” state and an “off” state based on the sensed ambient conditions, and wherein heat is applied to the glass member when the duty cycle is in the “on” state.

12. The refrigerated merchandiser of claim 11 , further comprising a plurality of mullions defining a plurality of openings, wherein a door is positioned over each of the plurality of openings, and wherein the controller is programmed to independently determine a duty cycle for each door.

13. The refrigerated merchandiser of claim 6 , wherein the sensor is coupled to the mullion adjacent the door.

14. The refrigerated merchandiser of claim 13 , wherein the sensor is disposed in a hollow portion of the mullion, and wherein the sensor is in communication with the opening via a hole in the mullion.