Maintaining an Air Compressor in Winter

31 Jan 2022 Elizabeth Jones

Within the colder months, your compressed air equipment may require a little extra maintenance. Here is an insight from Sales Engineer, Grant Robins on some of the most frequent breakdown queries we have assisted with over the years.

frozen pipe

Why won’t my Air Compressor start in the cold?

New compressors have a protective “low ambient temperature alarm”. This prevents the compressor from starting when the internal oil temperature is below 1°C. Cold oil has a thicker consistency, meaning the motor requires more amperage initially which can lead to the fuse tripping upon start up.

What can we do to help?

Air Energy Limited can install a thermostatically controlled heater into the plant room to keep the ambient temperature above 1°C and assist with preventing this in future.

Alternatively, if your compressor is not installed within an easily heated plant room, you can position a heater beneath the oil sump to warm the oil, once the compressor oil temperature is over 1°C, the compressor can be turned on and the oil temperature will rapidly climb.

Why is there moisture in my air lines when I have a dryer installed already?

This is one of the most common breakdowns calls we receive in the winter.

To understand why this fault occurs means describing some terminology. Pressure Dewpoint is the temperature at which water vapour in a pressurised system will turn to condensate. This means if you have a refrigerant dryer that is drying air down to 3°C, moisture will not be present in the air unless the ambient temperature of the air gets below 3°C.

There are a few solutions to this problem.

  1. Insulating pipework that goes through cold areas to decrease the effect of the ambient temperature, you may want to consider installing heat tracing.
  2. Rerouting pipework could assist if you have pipework going through a fridge/freezer or going outside before coming back inside, there will be a temperature differential which can cause the ambient temperature to drop below the pressure dewpoint in these specific areas.
  3. Installing a water trap in the above-mentioned locations where condensate can form. This will alert you of the condensate being produced and help prevent moisture having a negative impact to your set-up.
  4. Consider alternative dryers. If you are in a cold area, or working in a refrigerated atmosphere, there are alternative dryers that reduce the Pressure Dewpoint of the Air to -20°C, -40°C and even -76°C dependant on the process.

My air receiver fills with water quickly, do I need to consider this freezing?

The short answer is yes. At Air Energy Limited we usually complete dry receiver installations. This means we complete the install with the receiver after the dryer. Not only does this assist with preventing the receiver filling up with condensate but also reduces the potential to overflow the dryer.

If your set up has the receiver before the dryer and it is outside, there is a risk of it freezing up.

To prevent this, you can:

  1. Insulate the receiver and pipework attached
  2. Install heated condensate lines to prevent the drains freezing
  3. Consider moving the receiver to a location shielded from the elements
  4. Install heated drains or zero loss drains to prevent water from collecting

How do I foresee these issues happening?

That’s an easy one. Planned preventative maintenance. If you own an air compressor, you should be doing regular checks on it to make sure everything is working as you would expect, during these checks you will start to notice if something isn’t working the way you’d expect. This is your first sign something isn’t right!

How can I monitor my air compressor?

Monitoring a compressor has become significantly easier over the years, Air Energy Limited can now offer remote monitoring for 90% of air compressors. This allows us to see any signs an issue is imminent allowing us to prevent them happening in the first place!

What’s the strangest thing to consider with your compressed air system in the winter when the temperatures are close or below freezing?

Rodents. It’s not uncommon for rodents to find their way into the plant room and get comfy near the warm compressor, this can lead to problems like chewed wires, blocked motor fans and unpleasant smells. Grant once found a nest of cats under a compressor!

I have noticed a restriction in my air flow during the winter months, what can cause this?

When we experience cold weather and freezing temperatures are more likely, outdoor equipment is prone to more problems with frozen moisture. If you have inline filtration, depending on if it’s installed outside and how its installed, you can experience more moisture in your air lines. Another aspect of your compressed air system that can cause issues is your filtration and timer drains.

Filters before a dryer will have moisture coming into them, this moisture can freeze and cause the filter elements to clog. Clogged filters will cause a restriction in your air line and reduce the flow of air in your system. Air Energy Limited can install filters with trace heating to prevent this. We can also offer heat trace tape installation on pipework. Trace heating will warm the cold air in the pipes, helping to prevent moisture freezing and potential system failure.

Is there anything else I can do to prevent potential system failure in the winter?

Well maintained plant equipment should not cause any specific issues during the winter months. However, there is always a few things that can be done to increase optimal performance. Air leaks cause compressors to run more than required, not only wasting energy, increasing service frequency and creating a noisy work environment, while also wasting money. If your compressor overheats in the summer, modifications to the compressed air system to increase the efficiency can be scheduled to be carried out in the quieter winter months. Consider having your compressors air cooler removed and pressure cleaned.

Heat Recovery

Air compressors produce a lot of heat when compressing the air. A compressor produces a lot of heat as a by-product, this heat source can be repurposed and used to heat other parts of your building, or even preheat the water in your boiler (depending on the size of your compressor). This is known as Heat recovery. It is a very energy efficient method of heating another area of your building as it effectively costs you nothing, while reducing your energy consumption. As an example, a 22Kw compressor produces roughly 4Kw of heat. Heat recovery systems have become increasingly popular with new buildings and air compressors 30Kw and above.

Contact us

If you would like some free advice, or clarification on any parts information for compressed air set up, please contact our service team on 01992 586666 and select option 1.

Alternatively, you can email and one of the team will get back to you as soon as possible.

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