• Keep the door or lid shut! It sounds obvious, but time is critical for excluding warmth and moisture from the inside. Some models have an alarm light which comes on when the freezer door is not properly shut. Ideally, the alarm should be easy to access - some alarms are poorly positioned beneath the freezer door so as to not be visible from a normal standing position.
• If your freezer is nearly empty, put in some plastic bottles, three-quarters filled with water. This will reduce temperature variation within the compartment, and prevent the temperature from dropping sharply when the door is opened.
• The coldest part of a chest freezer tends to be on the compressor step; the coldest part of an upright tends to be the top shelf. Keep long-term storage items here.
• Moisture-proof packaging such as plastic containers, thick plastic bags and aluminium foil will preserve food quality by preventing dehydration and oxidation.
• Some freezers have a "fast-freeze" function, to ensure the rapid freezing of freshly loaded food. Remember to turn it off after a few hours, or running costs will be higher and constant noise could be a problem.

Temperature settings

• A freezer should be -18°C or below. Slightly warmer (no higher than -15°C) can still be OK and it'll make ice cream more scoopable, but food quality and storage times are likely to be affected. Its best to keep your freezer properly cold and store ice cream in the warmest part: the bottom of an upright and the top of a chest.
• Large temperature fluctuations can compromise food quality. One sign of this is if your ice cream develops crystals on the top - that means it's thawed a bit and refrozen. This will affect its texture and taste, and may well affect the quality of other foods too.
• A freezer needs to be able to cope with extreme temperatures because they're often kept outside the house. Freezers are designed to cope with ambient temperatures ranging from 10°C to 43°C. However, if your freezer is in a garage or shed, temperatures can easily get lower or higher than this, making it difficult to maintain the set internal temperature. It's best to use a thermometer to check, especially when the outside temperature changes significantly.
• Ideally, you shouldn't load a freezer with food that's at room temperature; cool it first so it doesn't affect the food already in the freezer.