By Tanya Olckers

Taking on the task of fitting gas systems into a busy international hotel like the Southern Sun OR Tambo is not easy. However, contractors rose to the challenge to ensure safety and efficiency.

Southern Sun Hotel

All images: Plumbing Africa

It’s a daunting task: stripping old, corroded, electrically and gas-heated hot water cylinders from a functioning hotel and replacing them with new instantaneous gas water heaters. This is especially difficult when the hotel you are working on has two wings: one with 100 rooms and the other with 272 rooms, a kitchen and conference venue.


Booster pumps.


Hot- and cold-water pipes.

The old staircase had to be replaced

The project, which kicked off in the middle of 2021 and concluded in January 2022, involved the colossal challenge of installing two new systems while keeping the old systems running at the same time. A busy hotel like the Southern Sun OR Tambo can’t afford a lengthy shutdown, so it was continuously occupied by guests while work took place.

The system had to be replaced because of corrosion and the extremely high costs of running existing gas electrical systems. The hotel had old, corroded and expensive electrical water heating in one wing and old, corroded and inefficient gas boilers with large hot water tanks in the other wing that needed to be replaced with more efficient, modern instantaneous gas water heaters. Brand Rinnai instantaneous gas water heaters, which are made in Japan, were selected.

The new gas boiler plant in one wing consists of 22 Rinnai gas heaters in a combined system that switch on and off automatically as demand in the hotel increases. The system is computer-controlled. The other hotel wing has a similar system, but because it’s smaller only 10 Rinnai water heaters were needed. The old wing has three times the number of rooms plus a kitchen and laundry, leading to greater water use.

To keep the hotel functioning while simultaneously changing over from one system to another, in both wings of the hotel, the new hot water plant was installed in a different position to the old one. This allowed the old plant to keep servicing the hotel until it was time to change over.

In the new wing, the gas was fitted on an outside wall adjacent to the boiler room and on the new wing, the new gas water heating plant was fitted on the roof of the old boiler room.

The roof of the old boiler room couldn’t carry the additional structural load and a special steel support base had to be designed and installed to spread the load on the existing structure, as determined by the structural engineer. Satellite Steel did the steel work and new stairs to get up onto roof as previous stairs were rickety.

Gas piping.

The hotel had noticed large savings due to the change. The new gas consumption is considerably cheaper than the gas and electrical energy used in the old systems.

To enable it to utilise this modern gas equipment installation, the hotel had to upgrade its Sasol gas supply. To do this, contractor Gas Care Services had to increase the pressure of the gas system. They had to change and modify the gas fire solenoid valves. Should there be a fire, and any two smoke detectors go off, it will automatically send a signal to close off the gas supply as a fire prevention measure.

Plumbers faced a tough task in bringing the hot and cold-water pipes to the new gas boiler positions while pipes were still operating from the old position. The existing hot water installation had two 10 000ℓ storage cylinders of hot water with a 75mm riser to roof and 14 ducts that were fitted with balancing valves and return to boilers in the old block. The new block had two 4000ℓ electric heated storage vessels. Both had bad leaks.

Gas heaters for the new wing

Gas heaters for the old wing.

The plumbers had to cut in new connections with valves. This was done onto the existing pipework so that both the old and new systems could work together – and ensure a quick changeover. Insulated copper hot- and cold-water pipework by Armaflex was used to connect to the new gas boilers. Lagging and cladding was provided by Insulpro, with copper supplied by Mac Steel. New hot water circulation pumps were also installed with new return pipework.

The new wing needed new hot water circulation pipes in the administration offices and the balancing valves all needed adjusting. All this was long, tough work for the plumbers who often had to work after hours so that the hotel could remain operational.

And, what happened to the old boiler room? It was turned into a storage area. 

Client: Southern Sun OR Tambo

Project Engineer – Wet Services – Steve Franklin from Wills Franklin Pretorius (Pty) Ltd

Gas and Equipment – Gas Heater Supplies

Gas Care Services – Installation Contractors

Plumbers – Rivers Plumbing

Steel Work – Satellite Steel Works

Copper from Mac Steel and Armaflex lagging and cladding from Insulpro. Gas heaters from Rinnai.

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