Does defrosting a commercial freezer make it work better?

 Is your commercial freezer’s performance slipping? The culprit might be hiding in plain sight: frost. 

It’s subtle and easy to overlook. After all, all freezers have some kind of frost build-up, right?  

True, but when this gets too bad, frost quietly drains your energy, reduces cooling efficiency and can even compromise food quality. 

Understanding why frost forms in commercial freezers – and how to manage it – means you can keep your freezer running smoother for years to come. That’s what this blog is all about. 

Why frost forms and how it affects performance 

Frost forms in commercial freezers when moisture in the air freezes onto the unit’s cold internal surfaces. This process begins when warm, humid air enters the freezer, typically through frequent door openings or inadequate seals. Once inside, the moisture in the air condenses onto the coldest surfaces, such as the walls, back and shelves, and then freezes, forming frost.  

In commercial freezers, the primary sources of moisture are: 

• Air – warm, moist air enters each time the freezer door opens. Even with good seals, the temperature difference can create a negative pressure that draws humid air from the surroundings. 
• Food – unpackaged or improperly sealed food releases moisture into the air inside the freezer. This moisture then condenses and freezes on the cold surfaces.
• Humidity – hot kitchens and food prep areas are usually humid. Moisture might enter the freezer through gaps, vents or when the freezer is filled or unloaded. 

As frost accumulates, it acts as an insulating layer, making it harder for the coils to absorb heat. This means the compressor has to work harder and longer to maintain the desired temperature, leading to increased energy consumption and potential overheating. 

The refrigerant system in your commercial freezer works as follows. The refrigerant in the evaporator coils (inside the freezer) absorbs heat inside the unit. When the compressor activates, it sends this heat outside the freezer through the condenser, which is why freezers and fridges give off warmth.  

So, frost’s impact on performance is measurable. Studies have shown that frost build-up can increase energy use by up to 20% and reduce cooling capacity by up to 30%. 

What are the signs that your commercial freezer needs defrosting? 

As we’ll discuss in the next section, your commercial freezer needs defrosting more regularly than a domestic unit. However, these are the signs to watch out for in the meantime. 

First, and most obviously, check how thick the frost (ice) build-up is. If it’s anything more than ¼ inch (5mm), it’s time for a defrost cycle. You don’t need to be too precise with your measurements here. Use a ruler or tape measure if you like, but a visual inspection usually tells you all you need to know. 

Second, monitor the thermostat’s cut-in time (the duration the compressor stays off before restarting).  

As frost accumulates on the evaporator coils, it gets harder for the refrigerant to absorb the heat, causing the compressor to run longer and the off-time to shorten. If the cut-in time shortens by a significant amount (say about 30%) – or the time the compressor runs increases by a similar amount – then frost may be impairing its efficiency. It’s time to start defrosting. 

Finally, monitor temperature fluctuations. Of course, this is far simpler if your unit has a digital thermostat on the outside. Check and log the temperature regularly across a few days. That way, you’ll have a good dataset from which to work. However, note that when your freezer isn’t working, you’re more likely to see greater energy bills than obviously fluctuating temperatures, unless the frost build-up is extremely severe or the freezer is on the way out. 

How often should you defrost your commercial freezer? 

There’s no ‘one-size-fits-all’ here. That’s because every shop, every premises, every business, every workplace is different. The trick is to find the sweet spot for your operations. 

The frequency of defrosting depends on all sorts of things. Here are just a few:  

• Type of freezer
• Use pattern
• Ambient conditions
• Energy bills
• Age and condition of your freezer
• Produce you store 
• How busy your staff are 

However, be aware of one thing: you should defrost your commercial freezer far more often than its domestic equivalent. A typical home freezer usually only needs a manual defrost once per year, or once you notice significant frost build-up. In contrast, commercial freezers may need defrosting every few weeks.