Backer-Springfield is recognized worldwide for its expertise in the
development of specially fabricated silicone and thermoplastic insulated
resistance wire for refrigeration anti-condensate applications. These
heating elements are available in a broad range of resistances from .22
ohms/ft to 5000 ohms/ft. with a tolerance of +/-
Whatever your requirements for insulated resistance wire, you’ll find
Springfield Wire, Inc. an excellent source for quality material,
competitive pricing and dependable service.
The majority of silicone and PVC heater wire that Springfield Wire
manufactures is used in domestic and commercial refrigeration
applications to prevent the formation of condensation on surfaces.
The successful use of either type of wire depends on three critical
- 1. Proper selection of the resistance (ohms per foot) to provide
the desired wattage.
- 2. Selection of the appropriate style of wire.
- 3. Proper installation in the application.
Proper Selection of Resistances
All Backer-Springfield heater wire is made to order to a resistance, as
measured in ohms per foot. This resistance value is based on the watts
per foot and voltage available in your application. The amount of heat
(wattage) required to prevent condensation around doors will vary
according to the design of the cabinet.
For walk-in deep freezers whose ambient is 30 F to below zero, 8-12
watts per foot is commonly used. Reach-in and walk-in coolers that
operate at a higher ambient temperature generally need 3-6 watts per
It should be noted that the above figures are only general
recommendations. Each application is unique and careful testing using
thermocouples should be done by the customer to ensure a proper and safe
design. Varying cabinet ambient and mullion constructions (steel,
aluminum, plastic) will all play key roles in the heat transfer between
the heater wire and the surface.
Thermoplastic (PVC) Insulated Resistance (Heater) Wire
Backer-Springfield’s thermoplastic (PVC) insulated heater wire is an
excellent choice for use in low wattage applications. This premium
quality thermoplastic jacket material has passed the most critical odor
tests of the domestic refrigerator manufacturers. In addition to being
used in bulk form for harness, PVC insulated wire is widely used in the
manufacture of foil bonded and sewn to foil heaters.
Silicone Insulated Resistance (Heater) Wire
Backer-Springfield’s silicone insulated heater wire is an excellent
choice for use in high wattage application of up to 15 watts per foot.
This wire is constructed using electrical grade fiberglass core material
and is insulated with our SW-200 silicone rubber. SW-200 is rated to
150C (302°F) and can go as high as 200°C (392°F) depending on
Many factors are to be considered when installing any heater wire in
domestic or commercial refrigeration equipment. The most important of
these is a good thermal transfer between the wire and the surface to be
heated. Installation of the heater wire may be done by taping the
heater wire directly to the surface or by bonding to aluminum foil and
then securing the self adhering foil to the surface. The foil bonded
design is generally used to ensure proper spacing of the heater wire,
ease of installation and good heat distribution.
When laying wire in grooves or channels around door perimeters, sharp
edges and corners must be avoided so that the wire is not cut or
abraded. Fiberglass or aluminum braid over the wire is available as
protection from such surface abrasion. Metal or plastic channels can be
used, and grooves that are cut into wooden door frames should be lined
with aluminum tape to prevent abrasion and also to reflect heat outward
toward the surface being heated.
If multiple passes of wire are used, it is important to keep them spaced
1/4” apart and not allow any contact. If the wire should cross itself,
the effective wattage at that point is doubled and a hotspot or burnout
If the wire exits through the wall of the cooler or freezer unit, care
must be taken to ensure that it does not become buried or encapsulated
in foam or other type of insulation. This causes poor heat transfer and
overheating which could result in failure.
It is important that heater wire be installed with a small amount of
slack at the corners of the frame. When the wire is energized, it will
move slightly. This "creeping” motion can cause abrasion if the wire is
installed too tightly and is under tension in the channel.