Freezer Floor Frost Heave Prevention
Subfreezing temperatures inside cold rooms, freezers, and ice arenas cause heat to be lost from the soil under the floor, even when it is well insulated. As the soil freezes, capillary action draws water into the frozen areas where the water forms a concentrated ice mass, known as an Ice Lens. As the Ice Lens grows, it heaves the freezer floor and columns, causing damage. Chromalox frost heave protection systems are designed to prevent an Ice Lens by keeping the soil underneath warm. The Chromalox frost heave prevention system is comprised of the following:
- Heating Cable (CPR, CZH, or CMI)
- EL Series Connection Accessories
- CTC or CIP Controls
- RTD Temperature Sensors
Use of Heat Trace in the Application:
CPR SELF REGULATING CABLE – Chromalox’s CPR Cable is designed to keep soil underneath cold rooms from freezing. Our CPR cable is constructed of a self-regulating polymer core that automatically & efficiently adjusts its heat output to changes in soil temperature along the length of the conduit. Chromalox’s CPR cable can be cut-to length to easily be pulled through conduit to protect soil from freezing temperatures. Chromalox’s CPR Heating Cable is available in four watt densities – 3, 5, 8 & 10 watts/ft and is approved for installation inside of conduit. Chromalox’s CPR Heating Cable is available for 120V or 208-277V and features 16 gauge copper bus wires to permit maximize circuit lengths. Our CPR Heating Cable is available with either a modified polyolefin or fluoropolymer jacket to protect the cables from abrasion and abuse.
CZH CONSTANT WATTAGE CABLE – Chromalox CZH constant-wattage heating cable is a proven, reliable solution for frost heave prevention. CZH cable features a parallel heating core that produces uniform thermal output – over its entire length. It is flexible at most ambient temperatures and can be easily pulled through conduit. It is rugged, easy to monitor and maintain temperature, and has zero inrush at start-up. With a fIuoropolymer electrical insulation over jacketing, CZH cable has out-standing electrical and thermal properties, and is well suited for frost heave prevention. An extensive range of wattages and voltages is available immediately from Chromalox stock.
CMI HDPE JACKETED COPPER MI CABLE – Chromalox CMI cables are copper-sheathed, mineral insulated heating cables that are covered with an extruded high-density polyethylene (HDPE) jacket and are supplied as complete factory-assembled cables ready to connect to a junction box. The series-type technology, inherent to all mineral insulated heating cables, provides a reliable and consistent heat source that is ideal for frost heave prevention
- Please note that National Electric Code requires ground fault protection (GFEP) for all heat tracing.
Important Design Notes/Best Practices:
FOR SELF-REGULATING AND CONSTANT WATTAGE CABLES:
After determining the approximate total length of heating cable, the number of circuits, and the junction box location, do a trial layout. In making the trial layout, follow these recommendations:
- Start and end each circuit in a junction box.
- Do not design more than one run of heating cable per conduit.
- Arrange the conduit so it uniformly covers the area to be heated.
- Maintain the design conduit spacing within 4 in (10 cm).
- Do not extend the heating cable beyond the room or area in which it originates.
- Do not cross expansion or other subfloor joints.
- Do not route the conduit closer than 4 in (10 cm) to the edge of the subfloor, drains, anchors, or other material in the concrete.
- Do not exceed the maximum circuit length allowed on a branch circuit breaker
- The maximum length of heating cable that can be pulled through conduit is 500 feet (150 m).
- The maximum total degree of conduit turn is 360 degrees.
- When the combined lengths of two or more circuit runs are less than the maximum circuit length allowed, these runs can be combined in parallel on one circuit breaker.
FOR MINERAL INSULATED CABLES:
- The conduits must be laid out in straight runs as shown in Installation section of this design guide
- Where cable lengths exceed 50 ft (15.2 m), the conduit must be accessible from both ends to allow long runs of cable to be pulled into the conduit.
- If it is necessary to stub-up the ends of the conduit, use a minimum 12 in (30 cm) radius in conduit bends
- Arrange the conduits so that they uniformly cover the area to be heated.
- Maintain the design conduit spacing within 4 in (10 cm).
- Do not cross expansion or other subfloor joints.
- Do not route the conduit closer than 4 in (10 cm) to the edge of the subfloor, drains, anchors, or other material in the concrete.
