Why Do I Need To Carry Out A Leak Test On My Air Conditioning System?

Why Do Leaks Occur On Refrigerant Circuits?


Occasionally we will recommend carrying out a leak test on your air conditioning or refrigeration system, to check for leaks in the refrigerant pipework.  Refrigerant leaks can occur for various reasons, including:

  • Deterioration of pipework over years, which finally results in a leak.
  • Leaks at joints – whether a compression fitting or a soldered joint.
  • Weakening of pipework or fittings, due to exposure to excessive vibration.
  • Physical damage to pipework, for example, pipework on a roof being trodden on.

Air conditioning systems contain refrigerant.

How Is A Refrigerant Leak Diagnosed?


A refrigerant leak is most commonly diagnosed due to a lack of heating or cooling performance – either suddenly (in the case of sudden damage to pipework and sudden loss of refrigerant) or gradually in the case where pipework has deteriorated and a pin-hole leak appears over time.

A leak test is a relatively expensive procedure, so a refrigeration engineer will normally spend time eliminating all other possibilities, before recommending a leak test.  Other reasons for non-functioning air conditioning could include:

  • Blocked coils on the indoor and/or outdoor unit.
  • The blocked air filter on the indoor unit.
  • Malfunctioning fan motor in the indoor or outdoor unit.

Salix engineers diagnose a refrigerant leak.

What Are The Risks Of A Refrigerant Leak?


As an approved refrigerant handler, it is essential that we make you aware of any potential refrigerant leak straight away, including our recommended next steps to rectify.  Refrigerant leakage is harmful to the environment and is governed by various rules as set out under F-gas regulations.  These regulations stipulate that systems containing certain quantities of refrigerant must be checked on a regular basis for leaks.  (link to https://salixmechanical.com/what-is-f-gas-and-what-are-my-responsibilities/).

Large refrigerant quantities are found in chillers like this one.

What Is Involved In A Refrigerant Leak Test?


A leak test sounds relatively straightforward, but due to the careful consideration needed when handling refrigerant gases, we have to follow a process every time.  The concept of ‘topping-up’ refrigerant gas in the event of a leak is a complete contravention of F-gas laws and should not be carried out.

A Salix engineer carrying out a repair.

A leak test and repair on an air conditioning system would typically include the following steps:

  • Recover all remaining refrigerant from the air conditioning system into a dedicated recovery cylinder. This will then need to be sent away for safe disposal by a registered refrigerant waste handler
  • Pressurise the system using OFN – oxygen-filled nitrogen. Putting the system under pressure should hopefully show up the site of any leak visually.
  • Repair the leak – whether it means re-doing a soldered joint, replacing a fitting, or even replacing a section of pipework
  • ‘Vac’ the system – using a vacuum pump, put the system under negative pressure to remove any moisture or other contaminants.
  • Re-fill the system with the correct quantity and type of new, virgin refrigerant.

This is a simplified summary of what is typically involved in a leak test and shows why this procedure can cost a lot more than customers first expect.

Salix are F-gas approved contractor and are certified to carry out all works involving refrigerant in air conditioning, refrigeration and other cooling systems.

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Rob Tuffin