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The Median Apartments

Edited by Rory Macnamara. Technical input by Willem Strydom, Ricky Savvides, HVAC and Wet Service Engineers, ACS Consulting Engineers.

This is the third of the residential apartment buildings which offer High-rise luxury living at affordable prices in the centre of Rosebank with Concierge & 24hour security, a few steps away from The Zone shopping centre and close to the Gautrain Station. The project commenced in 2017 and was completed end of 2021.

All photos by © Plumbing Africa Rory Macnamara

Like its sister block, The Tyrwhitt Apartments, this block will be served with natural gas and installed throughout the residential building to supply to the main gas boilers, all kitchen gas hobs, gas braais and gas fireplaces. The restaurant, situated on Parking level six (6), also ground floor, will also receive a gas supply. The building is new and consists of seven parking levels, five underground and fifteen apartment floors.

Image credit: © Plumbing Africa Rory Macnamara

Image credit: © Plumbing Africa Rory Macnamara

The main gas supply is from Egoli Gas and all fittings, associated with a safe and competent gas installation, were done by an accredited gas installer. The main gas chamber is fitted with gas regulators with gas filters, gas pressure relief valves and manual reset shut off valves.

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Pressure measuring test points are placed at the apartment regulators, which also act as purge points. Line pressure gauges (glycerine type) are installed on each main supply pipe in the gas metering chamber before and after the regulators for measuring gas pressure and the reduced pressure, to be supplied to the boilers, apartments, and restaurant.

All piping from the gas pipes at the site boundary into the building and to each apartment is in black mild steel as per SANS 62-1.

Steel pipe fittings, valves, and accessories were of the screw type if smaller than 32OD and not embedded as per SANS 62-2. If embedded and exposed these were welded if larger than 32OD.

Expansion of pipes is managed by use of pipe loops every 30m length of horizontal pipes and 15m of vertical pipes.

Piping inside of apartments was composite PE-X/AL/PE-X compatible with natural gas and complied with SANS 827 and were tested to 100Kpa minimum or as per the standard.
All gas piping was clear of any electrical system, conduits or cables by being 150mm minimum away from such service.

Gas boiler plant room

The 50-diameter supply pipes to the gas boilers were installed with a quarter turn emergency shut off valve outside the plant room with a permanent sign “GAS VALVE.” Two vent lines were constructed of black mild steel which were connected to a common 50 diameter vent line by the installer to all pressure relief valves or devices along the gas trains that required venting to the atmosphere.

Apartment supply

The main 80 diameter pipe in the water service cupboard forms a ring main and reticulates to all the gas riser pipes to each apartment. Each riser pipe was sized to accommodate the required gas flow for the appliances being served. Pressure gauges were installed at the highest point of each of the ten gas pipe risers, also in the service cupboards. Each apartment has its own meter for billing purposes.

Restaurant supply

The gas supply was installed as close to the restaurant as possible for onward connection by the restaurant owner. A pressure regulator, gas meter and pressure gauge were installed to this supply pipe.


All drainage was done according to SANS 10400-P and waste drainage for all internal appliances in each apartment from level 01 to level 15, including drainage for some areas in the Parking level. In general, drainpipes are of uPVC and those for showers were 50 diameter uPVC and were positioned before the slab was cast.

There were several 110 diameter stacks dropping from the top floors down to Parking level 7 where all the stacks connect to a 160-diameter drainpipe hung from the soffit of the slab. The main 160 diameter pipe drops down to Parking level 5 and connects to the municipal sewer connection provided by the Civil Engineer.

Rodding eyes were installed at the recommended intervals and junctions i.e., every 25m or at a change of direction of more than 45 degrees. Inspection eyes were installed at every junction.

Each stack has its own individual 110 diameter vent, combined under certain circumstances, at the top of the stack at its exit point on the roof. Vents open to the atmosphere were enclosed in weatherproof enclosure.

A 27kL sump is in the tank room in the event of overflow or draining from any of the tanks. All tank drainage and overflow piping to be in galvanised steel. Lifting station Grundfos pumps are controlled to stop/start at different water levels via ball float valves.

Typical gradient of 110 diameter waste pipes is no less than 1.60 and for 160 diameter pipes no less than 1.150.

Cold water reticulation

Sprinkler tank, domestic & hose reel/hydrant cold water storage tanks, hot water storage tanks are located on Parking level 1 in the tank room. Two 10 000 litre cold water tanks are located on the roof. Only cold-water piping was taken to the restaurant ablutions and kitchen with a PRV and metering valve. The plumber appointed by the restaurant owner will install the internal plumbing.

The Plumber connected from main supply to the plumbing/sprinkler ICV chamber on parking level 6 where a pressure reducing chamber was installed for domestic purposes.

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The pressure reducing chamber consists of a valve, strainer, PRV, water meter and another valve. A bypass pipe was installed with a valve for maintenance purposes.

Water will be supplied from a 90 cubic metre combined domestic water and hose reel/hydrant sectional steel tank with two internal sub-divisions located in the tank room on Parking level 1, using a Grundfos vertical multistage booster pump set complete with expansion tank. The domestic water portion of the main tank is reserved on the left side of the tank and equates to approx. 18 cubic metres in total. Water will be pumped to two 15 cubic metres sectional tanks located on the roof.

The two roof tanks are then connected to another Grundfos vertical multistage booster pump set complete with expansion tanks and VSDs (variable speed drive) to supply hot and cold water to each floor of the building. All horizontal pipes are installed with expansion loops as are all vertical pipes.

Hot water production and reticulation

Hot water is produced using two 105kW natural gas boilers/ two 11 000 litre low pressure hot water storage tanks which are heated by the gas boilers and store the water. Furthermore, two hot water circulation pumps are used to circulate water from the hot water storage tanks to the gas boilers at a flow of 5litres per second, thus 2,5litres per second per gas boiler. Water temperature is controlled at 65 degrees in the tanks.

Two heat exchangers in parallel are coupled to the hot water tank storage tanks in a closed circuit. Suitable water treatment and a rust inhibitor system is to be supplied for the closed circuit. Incoming water from the building main water supply pump set is heated by the heat exchanger before being supplied to the building. The pumps, one duty and one on standby, circulate water from the HWS tanks to the exchangers and back to the tanks. The pumps are variable speed drive (VSD) and are controlled by the hot water supply temperature to the building.

Two Grundfos hot water circulating pumps in duty and standby are used to circulate hot water throughout the building, ensuring constant hot water. Thermostatic balancing valves were installed on the hot water return pipes before connecting to the main hot water return ring main.

A shut off valve, PRV and NRV was installed in the closed hot water system near the tanks for the filling of the hot water tanks from municipal supply. The PRV is set at 200kPa when filling the tank and the shut off valve is closed after filling.

All hot water pipes were insulated with Armalfex insulation and cladded with galvanised sheet metal in plant rooms.

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Hot & Cold-water reticulation for apartments

Each apartment is fed from hot and cold Mepla pipes water pipe risers to each floor from the ring main on Parking level 7. Each riser feeds all the apartments vertically aligned. From the risers each apartment is fed with hot and cold water by means of a manifold.

A service cupboard is allocated for the pressure reducing and metering stations on the outside of the apartment close to the kitchen. Inside the service cupboard are: a valve, strainer, water meter, PRV and valve for the hot and cold-water pipes. The service cupboards also hold the water and gas metering stations.

Hot water supply and return pipes are copper and hung from soffit of parking level 7. Cold water pipes are galvanised steel.

Hydrant and hose reel installation

A 30m hose reel was installed within an area of 500 square metres. Such hose reels complied with SANS 543 and installed according to SANS 10105-1 and SANS 10400 -W.
Fire hydrants, 65mm, were installed within an area of 1100 square metre.

Two hose reel and hydrant vertical multistage pumps, one on duty and one on standby, were placed in Parking level 1 with domestic water plant room.

These pumps draw water from the tank located in the parking level 1 with 80 cubic metres of water reserved for hose reels and hydrants. A jockey/ booster pump draws water from the two tanks on the roof with 6 cubic meters per tank i.e., total of 12 cubic metre reserved for hose reels.

All hose reel and hydrant pipes and fitting were pressure tested to 2000kPa.
The mimic control panel is situated in the security room on the ground floor.

Owner and Management Renprop
Consulting Engineers ACS Consulting Engineers. Wet Services, HVAC, and Fire
Plumber RGS Plumbers
Pump suppliers Grundfos
Pump contractor JKJ Pump Contractors
Natural Gas piping and Gas Boiler Contractors High Speed Gas
Hot Water Tank Contractors SIRAC for RGS Plumbers
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