Bertha Gxowa Hospital: trading steam for heat pumps

By Ilana Koegelenberg

When the coal-fired steam boilers at the Bertha Gxowa Hospital’s nurses’ quarters in Germiston was declared ‘illegal’ and had to be replaced with a more efficient alternative, heat pumps proved to be the best solution.

COVER

Existing installation

The boilers at Bertha Gxowa Hospital were installed in the 1970s but since then, half the hospital has already been converted to electrical heating. However, the nurses’ quarters, currently housing 500 (with a 2 000 capacity) was still running on boilers, with its hot water needs being served by two hot water calorifiers.

When the team from Allsteam Engineering was called in last year to do maintenance on the existing boiler system, they found that the mandatory inspections and maintenance schedule were not adhered to, and the boilers were subsequently declared ‘illegal’. (It is regulated that all boiler systems must be inspected every 36 months.)

That’s when the decision to replace the system was made.

Client brief

Germiston doesn’t have adequate electricity to supply the entire area and energy usage is of huge concern. That’s why the hot water retrofit had to be highly energy efficient, refraining from adding more strain to the grid and keeping the electrical load as low as possible.

This was the requirement from the client. In addition, the existing system had to be kept up and running throughout the changeover so there would never be any loss of hot water to the premises.

The client also required a hot water temperature of 65°C minimum, as the system will be connected to the central heating at a later stage. 

System design

After the boilers were declared ‘illegal’, the Department of Infrastructure Development (DID) decided that it was time to replace them. DID, together with the Allsteam team, went to the drawing board to come up with the most suitable solution for the hot water requirement.


Because the boilers were declared illegal, the replacement had to be in place fairly quickly and the team had five weeks for the new installation.


Because energy was such an issue, using electrical elements for the installation was not a feasible option at all. That’s why the team suggested and specified heat pumps for this particular project.

As mentioned, however, the client required a water temperature of 65°C. Two 46kW heat pumps from WET were installed as the primary heating source, which heats the municipal supply to 55°C. The last 10°C jump is achieved with the help of two 24kW electrical heating elements to boost the temperature.

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There is a 5 000ℓ hot water storage tank for the system, which has a six-hour reheat period after it runs dry, usually during the peak-hours of usage.

The system is also equipped with two Wilo CRD heat pump circulation pumps as well as two standard star Wilo RS30-7 small circulating pumps.

The Allsteam team did the wiring of the control panels themselves.

Challenges

Because the boilers had been declared illegal, the replacement system had to be in place fairly quickly and the team had five weeks for the new installation. The engineer insisted on concrete slabs for the equipment, so this took another week off the installation time. But ultimately, it all came together in time with the two dedicated four-person teams of Allsteam on site.

The other challenge, as alluded to, was that the current installation had to remain up and running during the ‘switchover’. To achieve this, a temporary hot water system was put in place. A small 200ℓ hot water calorifier was installed, temporarily piped into the existing boiler system.

Another issue is that Germiston doesn’t only have problems with electricity supply, it also has low water pressure throughout the area — a huge concern. To overcome this, temporary booster pumps were installed.

A job well done

The system was completed within the allotted time and is currently up and running. The client is happy with the work and is looking at replacing or converting the remainder of its boilers in future.

List of professionals

Owner Department of Health
Contractor Wet services Allsteam Engineering
Product suppliers Heat pumps WET
Pumps Wilo

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