All images supplied by Pat Burke www. refrigerationandaircon. co. za 41
MICROCHANNEL HEAT EXCHANGERS
MCHEs: ADVANCED HEAT TRANSFER TECHNOLOGY( PART 2)
By Patrick Burke, FSAIRAC, RPM Consulting Engineers
MCHE coil technology: Let’ s cut to the chase. This is part two of a two-part series. voices
When placing a chiller enquiry, the various suppliers are always surprised by our insistence that the condensers be of the copper tube / aluminium fin type. In fact, our general specification clearly states that microchannel condensers are not permitted – by the way, the same will apply to plate heat exchangers and the use of hermetic type scroll and reciprocating compressors – when it comes to specifying chilled water generators.
The main reason behind our rationale is to combat the refrigerant leak issues commonly found with MCHC( microchannel) coils and, likewise, to address the fundamental pitfalls associated with the wide-spread use of multiple hermetic compressor circuits serving the same common refrigerant system.
In recent years( microchannel coils are relatively new technology) we have experienced an unusually high occurrence of refrigerant leaks on this type of coil, many occurring between three- and 10-years following installation of the chiller. In cases of clearly premature failure( three years or so) the supplier has opted to replace the offending coil panel with new, at their own expense.
I might add that replacing even one microchannel panel is not a cheap exercise. Try R200 000 for starters. You can only imagine the clients’ disapproving response when handed the quotation. After all, he has only recently forked out over R2-million for his new chiller.
RACA Journal I March 2026
Cross section: microchannel coil.
We were involved with three complete chiller replacements as a result of terminal microchannel condenser failure( multiple refrigerant leaks). The powers-that-be have taken the decision to cut their losses in all three cases, and purchase new chillers, rather than replace the condensers. Sounds drastic? Maybe, but in all probability, it is the best solution in the longer term given the toptier status of their property assets.
Have we opted for microchannel condensers for the replacement chillers? No way Jose! You must be joking. It’ s not to say that microchannel condensers are inferior in any way. Certainly not. In fact, they offer a number of distinct advantages over the conventional copper tube / aluminium fin condensers; inter-alia:
• Cheaper to produce( making for more cost-effective chiller offerings)
• Less refrigerant charge
• Higher efficiency
• Smaller footprint( less weight)
• Improved corrosion resistance
All images supplied by Pat Burke www. refrigerationandaircon. co. za 41