Coldroom and Freezer Door Heating
The door seal regions of commercial cold rooms and freezers, require warming:
A) To prevent door seals icing up and causing doors to freeze shut.
B) To prevent condensation near the door seals.
Heatec can select and make up a cable having a suitable output, which could require anything between 20 and 70 W/m around the door perimeter, depending on temperatures, door frame design and materials.
Heatec often provide replacement door heating cables to the industry.
The following, are likely causes of failure:
1. Mechanical damage.
2. Heating cable too long, resulting in terminations outside the frame, often with heating cables touching and heating cable extending into a conduit and sometimes the junction box.
3. Freezer door heating being run without the freezer in operation.
4. An inferior low quality cable used
5. Voltage selected, too high (with low voltage cables)
6. Cable in contact with a section of thermal insulation, such as polystyrene.
7. Corrosive materials such as cleaning products used in the door tracks.
8. Heating cable making poor thermal contact with the frame material.
Under-performing door heating is often due to the following causes:
1. Damaged or ill-fitting door seals including door seals not locating over the heating cable track.
2. Adverse conditions, such as discharge cold air blowing against the door, or the door being located inside the room instead of outside.
3. With low voltage: Undersized cable used from the transformer, causing excessive voltage drop, (4.0 sq mm recommended) or selected transformer voltage too low.
For long cable life, attention should be given to providing good thermal contact between the cable and the door track, especially for frames having wide heating cable tracks and outputs above 50 watts/m. Improving thermal contact allows the cable to run at a lower core temperature. Where the door track is much wider than is needed to accommodate the cable, lengths of aluminium kitchen foil can be crushed and packed into the track against the cable.
Information needed for ordering:
1. Length around heating cable track
2. Approximate room temperature
3. External temperature (eg. Coldroom, or ambient conditions)
4. Mains voltage or low voltage – and if we are to supply transformer to suit
Length is to include cold tail joins (which must be in the cable track) but not the cold tails. 500mm cold tails are supplied as standard. If you do not specify a watts/m output, Heatec will calculate based on the information provided. A standard aluminium frame with plastic cable track will be assumed. If a full plastic frame is used this must be specified, as the required output will be lower.
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Contact details:
26/17 Cairns St, LOGANHOLME. QLD. 4129. Australia.
Email: sales@heatec.com.au
Ph. (07) 3806 2326
International: Ph. 617 3806 2326
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