Thermal Mastic is a pumpable heat transfer compound that can be applied to gaps between metallic surfaces in different applications such as domestic refrigeration and heat sinks, rv refrigerator repair defrost thermostats or mold heater thermostats. In “heat release” ice makers, it can be used to promote and seal the mold heater thermostat to the ice maker mold, helping the ice maker to produce more ice and allowing for proper operation.
The present invention relates to a low cost thermal mastic compatible with polyurethane foam insulation in refrigeration systems that does not degrade the cell structure of the foam insulation. The composition of the thermal mastic of this invention includes low viscosity chlorinated paraffin as a vehicle, inorganic fillers such as aluminum silicate clay or powdered calcium carbonate and a wetting agent.
This formulation provides good heat transfer between the refrigeration tubing and the freezer walls without degrading the cellular structure of the polyurethane foam insulation. The mastic was tested on six standard chest freezer cabinets and the results of performance tests showed that this composition has superior properties compared to those of prior mastics employing parafiinic hydrocarbon vehicles which caused cell collapse in the foam insulation adjacent to the thermal mastic.
In addition to the excellent heat transfer properties of this type formulation, the mastic is also an effective sealer for polyurethane foam blocks in refrigerators and freezers. The mastic is applied about a 3/8″ bead along the entire length of the evaporator coil as shown in the front view below, and then spreads out as the freezer plate or fins are fastened to the cooling unit.
Another advantage of the mastic is that it does not glue the evaporator coil to the box, making it easier to remove or pull the evaporator coil at a later date. If your evaporator coil is recessed too far back into the foam block, it might need to be sanded or trimmed away before applying the mastic. If the mastic is applied correctly, this mastic will be an effective sealer for a long time to come, and will provide a much better cooling surface for the cooling unit.