www . refrigerationandaircon . co . za RACA Journal I February 2025 39
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GRANT LAIDLAW
Grant Laidlaw is currently the owner of the Air Conditioning and Refrigeration Academy ( ACRA ) in Edenvale . He holds a Bachelor of Business Administration and an associate degree in educational administration . He has a National Technical Diploma and completed an apprenticeship with Transnet . He has dual-trades status : refrigeration and electrical . He has been involved with SAIRAC for over two decades and served on the Johannesburg committee as chairman and was also president between 2015 and 2018 . Currently he is the SAIRAC national treasurer .
WELCOME TO THE SOLUTIONS PAGE
By Grant Laidlaw
Many people ask for assistance in the understanding of theoretical and practical aspects of the industry . I will endeavour to enlighten . We are going back to basics as I have questions coming in that indicate that the basic understanding necessary to work in the industry is not in place .
Kusaan asks : With regard to flammable refrigerant systems , it is obviously important to make sure that there are no leaks . What other aspects would be considered good practice when installing and maintaining these systems ? Thank you .
Hi Kusaan . Yes , refrigerant containment should be a priority for everyone who installs and maintains refrigeration equipment utilising flammable refrigerants . In reality , this applies to all systems . I have dealt with the safety aspects around flammable refrigerants in previous RACA Journal editions .
Let us ask the question , why is it desirable to reduce / prevent leakage of refrigerant ?
• Impact on the environment is minimised
• A system can only work properly if it is charged to its optimum charge . Lower refrigerant levels lead to a drop in efficiency and an increased risk of the system being incapable of meeting the operational requirements
• Leaking refrigerants can pose a risk to both health and safety when leaking into the environment
• To prevent perishable stock losses
• To maintain the cold chain
• Operating / repair cost savings
• To maintain a good client relationship
I am sure we can expand on this , but I think the point has been made . How do we improve refrigerant containment and leakage reduction ?
Servicing a system is of vital importance . Aside from the improved efficiency , reliability and longevity of the system , lack of maintenance can and will increase the frequency of leaks . As a condenser becomes dirty and blocked the heat transfer from the refrigerant is reduced . This causes an increase in the high side operating pressures which in turn place additional strain on joints and components in the system creating a higher risk of refrigerant leakage . In addition this places particular focus on efficient leak detection .
‘ Sealed systems ’ should be the aim of design and installation . This means that , for example , all flared type connections should be avoided as far as possible , and one should utilise brazed or welded connections . This then means that in the selection of components , one should select components with brazed connections unless there is a specific technical reason why permanent joints are not appropriate . The selection of refrigerant circuit components should be made under the premise that their design reduces the potential for leakage .
On the design side it is desirable to keep refrigerant charge to a minimum . This can be achieved if the refrigerant suction lines and liquid lines are exactly sized and kept as short as possible . In refrigeration applications , distances between plantroom ( e . g . condensing unit ) and evaporator position ( refrigeration load ) should be minimised as far as possible . In addition , heat exchangers and refrigerant receivers should be optimised to the system ’ s requirements .
Unnecessary refrigerant tubing increasing the amount of refrigerant needed and reducing system efficiency .
With a unitary air conditioning system place the evaporator unit and the condensing unit as close together as practically possible . This not only removes the need for additional refrigerant but improves the efficiency of the system .
Note : I am aware that some manufacturers recommend rolling
All Images Supplied by Grant Laidlaw
www . refrigerationandaircon . co . za RACA Journal I February 2025 39