By Tanya Olckers
University of the Free State (UFS) needed to provide a hot water system to cater for 1 200 students. They chose heat pumps.
All images supplied by SHC Consulting Engineers
When there are over 41 000 students that need housing, it’s a good idea to ensure that they have hot running water. The problem with supplying that much hot running water is that it can quickly drive up costs, especially when it comes to energy consumption.
UFS faced this conundrum when it wanted to replace five redundant hot water systems for five student residences and houses for about 1 200 students.
This was certainly a mammoth undertaking, but one that had to be done. The university had already been using solar power to drive up sustainability and to lower energy consumption, however, this on its own wasn’t enough to meet the municipality’s demands.
Pipe system.
It was decided to install heat pumps to bring down the cost of energy use and to reduce reliance on electrical boilers. The five redundant hot water systems were replaced by a central heat pump cluster with 12 Mitsubishi Electric CAHV hot water heat pumps.
The project was brought into reality by Bloemfontein-based SHC Consulting Engineers, who worked closely with the university to assist them in beefing up their energy efficiency. This involved retrofitting an existing infrastructure and the refurbishment of five existing residences to accommodate students. This also had to be done in such a way that the 1 200 students were subjected to minimal disruption.
One of four 19 000ℓ tanks installed.
Riaan Marais from SHC Consulting says, “Operating within the confines of an active university campus required strict adherence to schedules and protocols. With student residences still occupied during construction, the contractors faced stringent work hour limitations, particularly during exam periods. Navigating these constraints demanded close co-ordination and effective communication among all stakeholders.
” Planning and design started in September 2022 and the first phase of the project was completed in October 2023. This focused on the installation of heat pumps and storage vessels. The second phase was completed in February 2024 and focused on internal piping within the residences.
Design elements were central to the project’s success. “Of critical importance was optimising system efficiency while minimising downtime by strategically timing operations to coincide with off-peak electricity hours,” says Marais, “To achieve this, we proposed a strategy of closely monitoring campus energy demand and implementing load-shifting techniques.”
UVS boilers.
The strategy included 25%-oversized storage vessels so that there would be increased water reserves allowing operations to continue during peak demand periods. This meant that the system could automatically be switched off when maximum power consumption is reached.
Mitsubishi heat pumps and Wilo pumps were used. “Mitsubishi’s heat pump technology was selected for its efficiency and reliability,” says Marais, “There remains some reservation about heat pump technology in cold winter environments like the Free State, where many clients are adamant they want nothing less than 60°C water temperature.”
This temperature was set so that there was water safety, along with meeting heating needs and a desire to combat Legionnaires Disease. Heat pumps were elevated off the ground to combat the challenge of icy ground conditions. Belimo energy valves were installed to provide real-time monitoring of unit performance, which is needed to verify the effectiveness of the system in varying weather conditions.
Twelve 45-kilowatt heat pumps were installed to serve four 19 000ℓ tanks. Each tank has three internal heat exchanged coils and these are fed through a closed loop pumped water system from one CAHV 500 heat pump unit. To control the water temperature accurately, a Mitsubishi TW-TH16 temperature was installed.
These huge tanks had to be rigged and hoisted into a brand-new plant room. A dedicated facility was constructed for the heat pump cluster as well.
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