How and when to defrost your freezer to stop icy build-ups and save on energy bills

Defrosting your freezer is a chore that no one wants to do, but it’s essential to know how to defrost a freezer to ensure it maintains the right temperature and isn’t working overtime to keep your food cool. 

A lot of more modern freezers have a frost-free feature so when you open the door and warm air goes in, an automatic fan will remove the warm air so it doesn't condense into water and freeze producing ice.  

However, older freezers without this feature will suffer from a build-up of ice over time which will require defrosting. 

A build-up of ice in your freezer will waste more energy and increase your bills, so defrosting your freezer is important for its functionality and will save you energy and money. 

How often should you defrost a freezer?

Valerie Posner, head of business unit, refrigeration, at BSH Home Appliances says how you use your freezer will affect how often you need to defrost it.

‘If you are the type of person that regularly stands in front of the freezer with the door open for prolonged periods, or often put still-warm items inside the freezer, this will allow moisture to form in the cavity. This added moisture will turn to ice, which can build up and then will need removing for the freezer to function efficiently.’

But ideally, you should aim to defrost your freezer at least once a year, or when the build-up of ice is thicker than 6mm says Lara Brittain, kitchen expert at Currys. 'This will keep it working efficiently – and more importantly, will keep your food accessible at all times!'

Knowing how to defrost your freezer is a crucial part of the cleaning of your home and these tips will make it quick and easy.

How to defrost a freezer

A common question is ‘can you defrost a freezer without turning it off?’ unfortunately the answer is no, not if you want to do it correctly. 

Anna Batten, product manager at Smeg also says there are no quick fixes when it comes to defrosting your freezer. ‘Defrosting a freezer should be done as per the instruction manual of the appliance, otherwise, you risk damaging the appliance. Electrical appliances, such as hair dryers, or defrost sprays should not be used to speed up the defrosting process as this risks parts becoming damaged.’

1. Check your instruction manual

Before you start defrosting your best fridge freezer double check your appliance’s instruction manual in case it contains any instructions or tips that are specific to your freezer. We know these manuals are easy to misplace, so it'll likely be online if you can’t find yours.  

2. Turn down your thermostat

Anna Batten from Smeg says, ‘A few hours before defrosting, set the thermostat to the lowest temperature in order to further lower the temperature of the frozen foods.’ 

It’s best if you start your defrosting process when you have few items in the freezer so it will be easier to find a different place for your frozen food to prevent it from thawing out.

3. Turn the freezer off

Make sure you turn off your freezer at the mains and secure the cable and plug so there is no risk of either coming into contact with any water once the ice starts melting. Once you have removed all your food and placed them in cool bags - or sneaky tip newspaper - leave the doors open so warm air can start circulating and melting the ice. 

Lara Brittain from Currys, advises a way to speed up the process, ‘Place a bowl of hot water at the bottom of the freezer with the door open. This will help speed up the defrosting process. Once the water is no longer steaming, replace it.

4. Lay down towels

Depending on how long it’s been since your last defrosting, you may have a lot of ice to get rid of and therefore a lot of water. Place towels down in front of your freezer to soak up water, but also keep some spare towels aside to mop up any excess water. 

Once all the ice has melted, use warm water to clean the freezer and drawers and wipe down with a dry kitchen cloth or towel to finish. Check everything is bone dry because any leftover moisture will freeze.  

5. Plug it back in

'Turn the power back on and wait for the freezer to reach the proper temperature before refilling the appliance,' says Anna Batten from Smeg. It's recommended to keep your freezer at around -18 degrees celsius; once it has reached that temperature you can refill it. Consider some kitchen storage ideas to keep your freshly defrosted freezer in order.

‘The best energy-saving hack is to keep your freezer full,’ says Jordan Chance, heating expert from PlumbNation. ‘When your freezer is full, there is less room for warmer air to take up. The items that are already in your freezer will help to cool down any air that does sneak in. 

‘It is important to find a happy medium when stocking your freezer - as too much food could also block the cold airflow. We recommend leaving approximately an inch-worth of space between your frozen food items and the interior sides and roof of your freezer.’

What should you not do when defrosting a freezer? 

1. Avoid salt

Don’t use salt to defrost your freezer - 'Yes, salt does help clear icy roads but it can also corrode your freezer elements, seals and linings,' says Laura Brittain from Currys.

2. Don't use metal tools

‘Never try to be too forceful when clearing ice and especially don’t use metal tools. You’ll very likely do permanent damage to your fridge freezer,' says Laura. 

Once the ice has started to thaw, you could run a plastic or wooden spatula under a hot tap and use it to gently remove the ice. There are also various plastic ice scrapers available at Amazon to help you remove ice, but be gentle as you don't want to damage the cooling elements.

3. Avoid using sharp objects

'Although it may be tempting to hack at the ice with a sharp object, you may end up causing some serious damage to your appliance,' warns Mark Grieg head of supplier management at Marks Electrical. 

'Avoid using knives or any other sharp, heavy object to scrape the ice off the edges as there is a very high possibility you could puncture the walls of your freezer, making the appliance unusable.' A freezer puncture could cause your freezer to malfunction, the temperature to fluctuate and all of your food to spoil.’ 

4. Wait until the freezer is empty

While you can put some items back in a freezer once you've defrosted it, you should aim to minimise this, especially with frozen meat. 

‘If you’re planning to store your frozen food in the fridge, it’s best to avoid doing this with anything like frozen meat,' warns Laura. 'A bit of defrosting is inevitable and you should never refreeze certain foods once defrosted - even if it’s just a little bit.’ 

How long does a freezer take to defrost?

Patience is key when defrosting a freezer, and it depends on the size of your appliance and just how bad the ice build-up is. If a freezer has been left open for several days, you might have an Ice Age situation that takes longer than just a bit of frosty build-up. Generally speaking, it shouldn't take more than a few hours.