Alternative Drain Pan Defrost

Creation and evaluation of a system that optimizes the spacing and cost of a heating method for preventing the buildup of ice in a drain pan for an evaporator in -30 F conditions.

Problem Definition
There are concerns that the current system design provides too much heating for the desired result, this is creating unnecessary costs and inefficiencies within that model. Our goal is to develop a better and more efficient method that not only satisfies the design requirements but also does not require the stocking of specialized parts that have little to no variability in design.

Why Heat a drain pan?
Cool air at or below freezing temperatures can condense frost on the drain pan, during a defrost cycle the pan is preheated to a desired temperature above freezing so that the ice-melt from the condenser does not refreeze upon hitting the drain pan and can quickly leave through a drain.

If this process is incomplete ice buildup occurs resulting in a solid block of ice that can no longer be melted in a typical defrost cycle. The other concern is when too much heat is being applied to the pan, this will result in turning some of the water into steam as well as introduces excess heat into the room that must be removed after the defrost cycle.

A major part of our goals is to find the ideal conditions that minimize excess heat to the room while preventing issues that occur from incomplete defrost.

Current Methods
There are currently two common methods and their known issues:
 * Hot Gas
 * Costs of pressure rated pipe and the installation is high
 * Borderline effective below -30 F


 * Electric Resistance Rods
 * Often provides substantially more heat than necessary
 * Most suppliers provide only predetermined shapes and dimensions

Deliverables
Specify the most effective heating method Apply the Proposed Solution to a demonstration pan to test effectiveness Specify spacing configuration of heating elements Thermal mass balance to determine melting rate of ice chunks Detailed report discussing heating options, reason for choosing final design, and evaluation of final product

Specifications
Electric heat for drain pan only Average room temperature -30 F Heater(s) to be sized for the power draw similar to cooling fan motors Solution must be reliable, durable, and quickly and easily installed</li>