www. refrigerationandaircon. co. za RACA Journal I October 2025 21
Feature
at replacing energy-intensive geysers in its dormitories. The project began with a pilot phase of eight units, monitored by an independent electrical engineer to verify energy savings and performance( this case study will be published as a project article in a future RACA Journal).
This case illustrates the broader appeal of heat pumps for institutions seeking cost-effective, long-term energy solutions. According to Gomez, investment payback periods are often as short as 18 months, thanks to the significant energy savings and lower maintenance costs.
Unlike integrated or combo heat pump systems, MD’ s approach relies on widely available air-conditioning components. Should a component fail, repairs are easier and cheaper, since standard condensers are far more accessible than proprietary heat pump parts.
Supplied by Derick Gomez
Installation commencing at Lydenberg High School.
design replaces traditional geyser elements with a specially engineered heat exchanger, effectively turning a standard geyser into a high-efficiency heat pump water heater.
Gomez’ s design hinges on the concept that“ simplicity is the height of sophistication”. By stripping away the usual clutter – multiple control systems, switches and sensors – his system reduces the points of failure and lowers production costs. The heart of the system lies in using a conventional 9 000 or 12 000 BTU air-conditioning condenser unit paired with a custom-made heat exchanger. The geyser’ s electrical element is removed entirely, and the exchanger is fitted in its place.
The result? A system that uses the refrigeration cycle’ s‘ hot side’ to heat water, with a Coefficient of Performance( COP) of 5.6 – well above most standard heat pumps and air-conditioning units. This translates into serious energy savings. Traditional geyser elements draw 3 – 4kW, while Gomez’ s heat pumps operate at only 700 – 800 watts, offering institutions dramatic reductions in monthly electricity use.
A CASE STUDY FROM LYDENBURG A real-world example of this technology is currently being implemented at a large school in Lydenburg, Mpumalanga. The school is undergoing a phased rollout of 80 units, aimed
“ A common issue is oversizing, where a unit is too powerful for the room it serves.”
Several key features make MD’ s system particularly attractive to facilities managers and technical teams:
• Liquid refrigerant heating: A technique Gomez adopted years ago, now mirrored in newer air-conditioning systems.
• Extended pipe runs: Units can be installed up to 15m away from the geyser without upsizing, unlike many heat pumps that max out at 7.5m or 10m.
•‘ Inverter-like’ operation: The system gradually increases amperage as the water temperature rises – starting from as low as 2.9 amps – mimicking inverter efficiency without the cost or complexity.
While its primary function is water heating, the system can also be adapted for comfort cooling with minimal modification, highlighting its design flexibility.
EFFICIENCY VERSUS SOLAR AND GAS Heat pumps are often compared to solar water heaters and gas geysers. However, Gomez argues that heat pumps consistently outperform both, especially in climates with limited sunlight or rising gas costs. Solar systems may offer daytime efficiency but frequently revert to using their electric elements during high-demand morning and evening periods, offsetting the gains made during daylight hours. In contrast, heat pumps operate independently of sunlight and offer reliable savings regardless of the time of day.
Additionally, with potential LP gas price hikes and supply concerns in South Africa, many institutions are now favouring electric heat pumps as a more predictable and scalable solution.
MD Airconditioning’ s system also stands out for its use of locally sourced materials. While outdoor condenser units are imported, the custom heat exchanger components – such as the copper coil and stainless steel flange – are proudly South African, sourced from manufacturers like Maksal and local suppliers of 316 stainless steel. Gomez notes that while local components may be more expensive than imported alternatives, the quality and longevity are superior.
www. refrigerationandaircon. co. za RACA Journal I October 2025 21