Self-positioning system forces the heating element to return to its correct position at the beginning of each defrost cycle.
Damage to refrigeration evaporators can be eliminated with a self-positioning
system developed by Colmac Coil Manufacturing, Colville, Wash.
During a defrost cycle, the amount of expansion and contraction of heating
elements can be relatively large. The repeated defrost cycles, along with the
associated re-freezing of melted frost, can result in the heating element
‘creeping’ or ‘walking’ out of the heat exchanger.
“Understanding the mechanics of the heating element ‘creeping’ issue was one
the most challenging aspects of solving this issue,” says Roger Williams,
Colmac's engineering manager. "Once we understood what was happening, the
design team was able to brainstorm several new prototypes.” The group invented
the now-patented self-positioning system for electric-resistance heating
“The new self-positioning system works well for electric defrost coils at
any temperature and in applications where electric re-heat is required,” says
Jeremy Olberding, sales manager, who was on the design team.
The self-positioning system simplifies installation by minimizing the number
of parts and eliminating separate ground straps to electrically ground the
element. The system forces the heating element to return to its correct
position at the beginning of each defrost cycle.
“Reliable operation of evaporators, especially in unattended cold stores, is
extremely important,” Williams says. "The development of the heating
element self-positioning system has virtually eliminated heating element
failures in the field.”
To view the patent, go to www.google.com/patents and type the patent number
US 7,712,327 B2 in the search box. For additional details, go to
http://tinyurl.com/3lvf6mp on Colmac's site and view the technical bulletin.
End 'Creeping' Damage from Repeated Defrost Cycles
November 9, 2011