heat tracing for the refrigeration industry

Thermon South Africa (Pty) Ltd.
HEAT TRACING FOR THE REFRIGERATION INDUSTRY
THERMON TRACE HEATING CABLES
THERMON self regulating trace heaters cover the complete range of applications from frost protection
to high temperature industrial installations.
This leaflet outlines applications in the freezer industry
where THERMON trace heating cables can be utilised.
These cables together with a complete range of
components have been specifically designed for low
temperature use in the freezer industry.
The Self Regulating design renders the heater burnout
proof particularly at ‘cross-overs’ as the output will vary over
its entire length depending on temperature.
TYPICAL REFRIGERATION PLANT
Thermon South Africa (Pty) Ltd.
P.O. Box 24110, Lansdowne, Cape Town, 7779
47 Flamingo Crescent, Lansdowne, Cape Town, 7780
Tel. +27 21 762 8995
Fax: +27 21 762 8996
Gauteng branch.
P.O. Box 1035, Isando, Johannesburg, 1600
7 Vuurslag Ave, Spartan Ext 7, Kempton Park, JHB,1619
Tel: +27 11 966 9800
Fax: +27 11 392 5235
Email: sales@thermon.co.za
Web: www.thermon.co.za
Document no. U-IMS-COR-DF-006 Rev 03
Thermon South Africa (Pty) Ltd. Reg. No. 2015/020118/07, VAT No. 4750268387, Directors: G.P. Alexander, R.L. Bingham, J.C. Peterson
The schematic diagram above shows many applications where THERMON heat tracing cables may
be used on refrigeration plant.
In outdoor installations, particularly in cold climates it is most important to maintain minimum
operating temperatures to ensure that refrigerant gases remain as a vapour.
The following application notes describe where the heater cables may be used on refrigeration plant,
cool rooms, and commercial freezer cabinets. Thermon will be pleased to provide assistance on the
selection of heater cables to suit your application.
All heater cables operate on 240Vac power supply. Low voltage designs are available on request.
HEAT TRACING APPLICATIONS FOR THE REFRIGERATION INDUSTRY
LIQUID RECEIVER
A heater cable may be required in cold climates to maintain refrigerant liquid temperature for optimum
system efficiency.
OIL SEPARATOR
A heater cable may be required to prevent liquid refrigerant returning to the compressor by
maintaining it as a vapour.
SUCTION LINE ACCUMULATOR
A heater will assist boil off and ensure that the refrigerant remains as a vapour back to the
compressor.
Suitable Heater cables for these applications are CSR, BSX, RSX 15-2, CCH crankcase heater with
strap or CDH condensate drain heater.
COLD ROOM DOORS & COLD ROOM THRESHOLD
Warm air entering a cool room will condense and freeze
upon contact with a cold surface.
Heater cable installed in the doorway architrave or sliding
door seal increases the surface temperature above 0°C
and prevents ice forming between frame and door.
Ice may also form at the cool room threshold where
warm air enters, condenses, and freezes. This is
prevented by running three or four runs of heater cable in
floor channels, conduits, or sawn slots directly in the
concrete.
Recommendation: THERMON RSX 15-2 Self Regulating
Heater Cable or CSR Heater Cables are recommended.
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COMPRESSOR CRANKCASE HEATER
Compressors may be damaged by the formation of
refrigerant liquid in the crankcase particularly after long
‘off’ periods.
It may be necessary to heat the crankcase to evaporate
the refrigerant trapped in the oil, particularly outdoor
installations in cold climates.
Recommendation: THERMON RSX 15-2 Self Regulating
Heater Cable or purpose made crankcase heater for
compressors, type CCH complete with strap.
DRAIN LINES
The drain line from the drip trays also requires heat
tracing to prevent ice formation. The heater may be
attached to the underside of the pipe in one straight run,
or spiralled if required.
On plastic pipes the heater cable should be covered with
aluminium foil tape to assist heat dispersion. The heater
cable may also be run inside the pipe provided the
connection and end seal are external.
The drain line must be insulated with minimum thickness
of 25mm.
Recommendation: THERMON RSX 15-2 Self Regulating
Heater Cable or purpose made Condensate Drain
heater for drains, type CDH.
PRESSURE RELIEF PORTS, OR SAFETY VENTS
These are mounted in the cool room wall and used to
maintain normal atmospheric pressure allowing air to
enter or exhaust as required.
They typically comprise a box section with moving vanes
which must not become frozen.
Heater cable is spiralled around the box section at
approximately 80mm centres and preferably insulated.
Recommendation: THERMON RSX 15-2 Self Regulating
Heater Cable
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Document no. U-IMS-COR-DF-006 Rev 03
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FIRE PROTECTION SPRINKLERS
Where these are installed in cool rooms trace heating
will be required to prevent freezing on exposed pipe
work and fittings.
The heater cable rating will depend on the cool room
temperature, pipe size, and insulation thickness.
Recommendation: THERMON RSX 15-2 Self Regulating
Heater Cable
DRIP TRAYS
Drip trays are required to collect water droplets from the
evaporator coils during defrost cycles.
Formation of ice may be prevented by laying a heater
cable in the tray, alternatively, attached under the tray.
The spiral pitch should be 150-200mm, and the
underside of the tray should have a minimum of 25mm
insulation.
Recommendation: THERMON RSX 15-2 Self Regulating
Heater Cable
FROST HEAVE PREVENTION
The substrata of freezer floors will withstand cold
temperatures for a period of time, however if the ground
temperature will eventually drop below freezing. At that
point if water is present in the substrata frost heave of the
freezer floor will occur. If severe, this will damage the
foundation slab with the formation of cracks.
Design and installation guides are available for these
applications and Thermon staff is available to assist with
the design process.
Recommendation: THERMON RSX 15-2 Self Regulating
Heater Cable
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Document no. U-IMS-COR-DF-006 Rev 03
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SUPERMARKET FROZEN FOOD CABINETS
Wherever warm air is in contact with cold surfaces such
as the ‘frost-line’ or rail on open chest freezers then
condensation will occur. Similarly with display cabinets,
around doors and light fittings.
Trace heaters, or ‘anti-sweat’ heaters successfully
overcome these problems.
Recommendation: THERMON RSX 15-2 Self Regulating
Heater Cable or Thermon CSR Heater Cable
AIR OR WATER COOLED CONDENSERS
Where these are installed outdoors in cold climates a
trace heater may be required to prevent freeze-up.
Insulation should be applied over the heater
Recommendation: THERMON RSX 15-2 Self Regulating
Heater Cable
FAN COWLINGS
Fan cowlings on evaporator-blowers may ‘ice up’ and
cause fan seizure.
This may be avoided by spiralling heater cable around
the cowling at 50-80mm centres. Aluminium foil tape and
insulation over the heater would assist.
Recommendation: THERMON RSX 15-2 Self Regulating
Heater Cable
EVAPORATOR BENDS
Defrost heaters in evaporators may not always extend to
the bends, and therefore these may be traced with heater
cables to assist the defrost operation.
Recommendation: THERMON RSX 15-2 Self Regulating
Heater Cable
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Document no. U-IMS-COR-DF-006 Rev 03
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Heat Tracing for the
Refrigeration & Freezer
Industry
Tel: +27 11 966 9800 (JHB)
+27 21 762 8995 (CT)
sales@thermon.co.za
www.unitemp.com/contact
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