Case History 6- Project: Warming Cabinet.

Objective : Our client had been using Silicone Rubber heaters to heat large shelves in a Warming / Display Cabinet. They needed to cost reduce this product and needed to achieve more even temperatures across the shelf surfaces.

Challenges : A good deal of heat was being lost through the cabinet walls and this was the reason for the uneven shelf temperatures. Our client was assembling four silicone rubber heaters to each shelf in order to heat the large area.

Since the product needed to be such a small size, there was very little room for the heater. A space of 1.8" (46mm) x 7.5" (190mm) x .8" (20mm) is all that was available for a heater in the most desired product configuration. To accommodate 1400 watts @ 240 volts and squeeze in safety devices would be difficult - especially with adequate electrical spacings for CE approval.

Solutions and their impact :

• Farnam designed a larger single piece mica surface heater. The heater is the full size of the shelf. Our inherent heater cost is 55% less than what had been used.
  
• The single piece construction generated additional savings for our client since they no longer need to assemble, clamp, and wire four separate parts.
  
• By studying the application more carefully, we were able to profile a heat pattern which concentrates more circuit in the areas where the greatest heat losses occur. The greatest heat loss areas are the corners where structural supports conduct heat away. The edges also see high heat losses. We concentrated 70% of the circuits in these areas and have been able to improve the temperature differential from +/- 23 degrees to +/- 7 degrees.