An Introduction To Plumbing
Plumbing involves the installation of pipes and fi ttings for water, gas and sewerage reticulation. Water is divided into hot and cold and sewerage into waste water and soil water. Plumbing also includes the installation of rainwater and stormwater systems. Water supply and sewerage are two important aspects of plumbing, which play a very important role in the built environment and society as a whole. Plumbing is therefore one of the more regulated trades in the building industry, where only a registered licensed plumber can undertake plumbing work. The aim of this section is to provide technical information as a guide, and basic product knowledge to enable the reader to compile a specifcation and an accurate cost estimate of what a specific plumbing point or installation should cost.
Here are some day to day examples of plumbing terminology for the domestic market:
- supply and fit a bath or basin point. (This means to supply all materials and labour to bring the necessary water to the point where the bath or basin are to be installed but excludes the bath or basin)
- supply and fit 110mm main drain. (To supply the piping and couplers, dig a trench to lay the pipe in, and lay the pipe to the building inspector’s satisfaction.)
- install a geyser only. (Fit a geyser, connect the piping to it and check for leaks. This would exclude the costs of a geyser and pressure valve as well as the electrical installation.)
- supply and fit a geyser. (This would include the supply and installation of the geyser and related items to a stage where the geyser would be deemed operational)
Building Regulations And Minimum Specifications
Plumbing specifications and regulations are probably the most complex and certainly contain volumes of information. Under this section we have included regulations of a general nature. The SABS 0400 – 1990 document is comprehensive and a copy is essential for those who require more detail on specifications and building regulations. It is wise to always check specifications with local authorities before designing and certainly before construction. Some regulations vary from authority to authority.
Extract from a bank’s minimum requirements
Gutters and downpipes
Gutters, downpipes and rainwater goods shall comply with SABS specifications and fixed in accordance with the manufacturer’s specifications.
All rainwater to be discharged away from the walls below the DPC level.
Where gutters and downpipes are omitted, a concrete apron of at least 1 metre wide (this is to be approved on site) must be cast around the buildings to discharge water away from the buildings.
Valleys, box gutters and soakers shall be of an approved material, size and design and fixed in accordance with the SABS specifications.
Flashing shall be an approved and of durable material and fixed in accordance with the manufacturer’s specifications.
The water supply system shall be in accordance with the Local Authority requirements.
At least one stand pipe shall be erected in a suitable position and all materials and fittings used shall comply with SABS 509.
Where water is not available from the local authority, water from a borehole for domestic use must meet with the necessary health requirements.
Borehole water for domestic use shall provide a yield of at least 1500 litres per hour. A valid test certificate of the water yield must be furnished.
All drainage work to buildings shall be carried out by a registered plumber and drains shall be accurately laid to lines and gradients shown on the drainage drawings as approved by the local authority.
All drains shall be tested and passed in accordance with the National Building Regulations and the deemed-to-satisfy rules of part of SABS 0400, before the property may be occupied and the drains put into use.
Stormwater drainage and seepage water control
Stormwater shall be discharged away from the buildings by means of precast concrete stormwater channels, surface or underground drains.
Adequate precautions shall be taken to drain surface and seepage water away from buildings.
The necessary precautions are also to be taken to prevent flooding and damage of buildings in terms of the local authority and the bank’s requirements.
The bank reserves the right to call for stormwater drainage plans designed by a professional engineer and such work is to be carried out in strict accordance with the professional engineer’s specifications.
Septic and conservancy tanks
Septic and conservancy tanks shall be designed and constructed in accordance with deemed-to-satisfy rules of part P of SABS 0400.
French drains and soakage pits
Any french drain to be used on a site to receive effluent shall be designed and constructed in accordance with deemed-to-satisfy rules of part P of SABS 0400.
Drainage clearance certificate
The bank may request that a drainage clearance certificate be furnished for any type of drain.
Extract from SABS 0400-1990
Plumbing installation drawings and particulars
Where such details on more than one floor of any building are identical, they may be indicated on the drawings of one such floor only; provided that where such details are so indicated, the drawings of other floors concerned shall be suitably annotated to indicate where such details may be found.
Any drawing of a fire installation shall contain as many plans, sections and elevations as may be necessary to show, where relevant, the following:
- the location and size of any existing or proposed communication pipe serving or intending to serve any building or site;
- the location of any pipe, the size of such pipe and the material of which it is manufactured;
- the location and capacity of any storage tank;
- the location of any overflow;
- the location of any pump; and
- the pressure for which the installation has been designed.
Any drawing of a drainage installation shall contain as many plans, sections and elevations as may be necessary to show, where relevant, the following:
- the location, size and gradient of any drain and any connection point to such drain, in relation to a datum established on the site and the level of the ground relative thereto;
- the location of any point of access to the interior of the drain;
- the location of any trapped gully;
- the location and details of any septic tank, conservancy tank, private sewage treatment plant or sewage pump;
- the location of any percolation test hole excavated on the site and of any french drain;
- the location and arrangement of any sanitary fixture served by the drainage installation;
- the location and size of any soil pipe, waste pipe and ventilating pipe or device;
Control of plumber and plumbing work
No person shall perform the trade of plumbing as contemplated in government notice no. r1875 of 31 august 1979 unless he is a trained plumber or works under the adequate control of a trained plumber or approved competent person.
Where any person who is not a trained plumber has been practicing the trade of plumbing and was required in terms of any local authority by-law to register with it before so practicing in its area of jurisdiction, he may, if he is registered, continue in its area or the area of any other local authority if such registration is acceptable to such other local authority.
No local authority shall, for the purposes of these regulations, register any person to practice the trade of plumbing after the coming into operation of the Act.
Any person not being a trained plumber or not being a person contemplated in subregulation (2), who practices the trade of plumbing shall be guilty of an offence.
Any trained plumber who causes or permits any person who is not a trained plumber or not a person contemplated in subregulation (2), to practice the trade of plumbing without adequately controlling the work done by such person, shall be guilty of an offence.
No owner or person shall commence or continue the erection or demolition of any building unless approved sanitary facilities for all personnel employed on or in connection with such work have been provided or are available on the site or, with the permission of the local authority, at some other place; provided that where such facilities have not been so provided the local authority may order the cessation of such work until the required facilities have been provided, and, should such order not be complied with, the local authority may install such facilities and recover the costs of such installation from the owner of the site.
Any owner or person who contravenes any provision of this regulation, or fails to comply with an order served on him in terms thereof, shall be guilty of an offence.
Sanitary facilities shall be so sited as not to be offensive and shall at all times be maintained in a clean and hygienic condition, and shall, unless they are of a permanent nature, be removed by such owner or person immediately until such building work has been completed.
Sanitary facilities shall be provided at the rate of not less than one sanitary facility for every thirty (or part of that number) of the personnel concerned.
Provision of sanitary fixtures
The number of sanitary fixtures to be provided in any building shall be based on the population for which such building is designed, provided that:
- where any particular occupancy, separate sanitary facilities are provided for each sex, the number of sanitary fixtures installed for them shall be based on the population of that particular sex for which such facilities are intended, and if the number of persons of each sex cannot be determined it shall be assumed that they are in equal proportions;
- where fixtures are to be situated in separate groups, the numbers of fixtures in any group shall be based on the calculation of that portion of the total population for which the group is intended;
- any building for which the population cannot be determined shall, where such building contains one or more habitable rooms, be provided with at least 1 wc pan and 1 washbasin.
The minimum number of sanitary fittings to be provided in any building shall:
- be situated in places which are convenient of access; and
- where necessary shall be designated for the use of males or females or both; provided that any room containing fixtures designated for the use of both sexes shall be capable of being locked from inside.
Any means of stormwater disposal on any site shall include:
- In the case of any building on such site, roof valleys and gutters and downpipes or, where gutters and downpipes have not been provided, other means of ensuring that stormwater from any roof is controlled and will flow away from such building; and
- Any surface stormwater drains, channels or below- ground stormwater drains that may be necessary to convey stormwater away from such site or from one part to another part of such site.
Access to Stormwater drains
On any stormwater drain ready means of access shall be installed at such intervals that no part of such drain, measured along the line of such drain, is more than 40m from such means of access.
Connection to stormwater sewer
Where any stormwater sewer is available in any street or servitude abutting any site to be provided with stormwater drainage, the owner of such site shall, if so required by the local authority, at his own cost, install one or more stormwater drains to be connected by the local authority to such stormwater sewer.
Use of street surface drainage system
Where the local authority considers the capacity of any street surface drainage system to be adequate to accept the discharge of stormwater from any site, it may permit such stormwater to be so discharged; provided that the owner of such site shall, where so required by the local authority, at his own cost provide one or more conduits to convey such stormwater to such street drainage system.
Sanitaryware And Fittings
The product list of sanitaryware and fittings is so large, the more basic, everyday products have been listed. The following table will give a clear indication of sizes. There is a wide variety of local and imported items, which can be viewed in showrooms throughout the country. Extensive product catalogues can be obtained from manufacturers and importers.
Planning a bathroom
It is easier to rectify problems on paper whilst still in the planning phase. Try to visualise the space available and think your bathroom through. The bathroom layout should attend to specific needs and purposes.
Things to focus on:
- Find a focal point – bath, shower, vanity, etc.
- If you have a large window, place the bath underneath in order to present a smart picture when you window dressing is done. It is also charming and relaxing to look into a garden after a tough day at work. A bathroom could be made luxurious by adding a spa bath.
- In a small bathroom, the shower is the most expensive item in the room – show it off
- Hide the toilet. If your bathroom space allows for it put this sensitive item behind a door. The more private, the better.
- Add screening walls – vanity height or the ceiling to add dimensions to the space available.
- The various items – bath, shower vanity, should flow together. Try to avoid putting each item in a corner.
- The main bathroom should have a double vanity, if space allows, as well as a bidet. If space only allows for a shower, special touches can be added, for example, a few side jets, two shower arms and roses and a shower rail in order to adjust the height of the shower rose.
- If the second bathroom has to cater for more than one person, try to attend to their needs – for example, separate packing space in which each person can keep their belongings.
- Create a space for laundry. Add a couple of hooks to hang wet/used towels, or robes. Create space for extra towels – various bathroom accessories are freely available. Allow for a good size mirror above the basin.
- It does not matter how minor, but try to follow one chosen theme throughout the bathroom – for example, ensure that the tap colour combination is the same as that for bathroom accessories. Use the same tap range throughout the house. If the vanity has frosted glass panel, used matching frosted glass on the shower door.
If you are building a house with resale value in mind, have a subtle scheme that is not too specific. Remember that it is generally the bathroom and kitchen that sells a house.
Trends vary from time to time, but basic things like white sanitaryware, chrome taps and accessories and subtle tile colours will always be acceptable.
Local SA Bath Installation Procedures
Over 95% of South African Houses have concrete floors. A sand and cement bed (mortar bed) is used to install the bath and shower tray.
The recommended ratio mix of sand and cement is 5:1 (five parts sand to one part cement). Make sure that the area around the waste is free of all materials so the waste fittings can be attached.
Decide on the bath’s height. Approximately 150mm higher than the height of the bath, or 3 tiles high, mark a plumbline on the wall at the height you have decided.
Securely mount the wall battens on the plumbline that has been marked. Make sure that the plumbing is ready for the next step
Mix the mortarbed, using 3 spaced brick bed rows, under the bath’s base, making sure that the first row is close to the waste.
Connect up the plumbing
- Fill the bath half way with water and allow the mortarbed to set
- Brick and plaster up the front and end of the bath
- Tile up the required area
- Using a mildew resistant silicone, seal the area between the top edge of the bath and tiles
- Clean bath and check for scratches
- Small scratches may be removed by using a metal polish, e.g. Brasso.
- Deeper scratches may be removed by using 1200 grade water paper and polished up with a metal polish (rubbing compound).
It should be noted that many companies sell fibreglass baths as acrylic baths. This can be very misleading, as the quality of acrylic is far superior. Always remember to state ‘acrylic’ bath and differentiate acrylic from fibreglass baths.
Fibreglass baths are made out of fibreglass with a thin (1mm) coat surface.
Acrylic baths are made using a 5mm acrylic shell, which is heavily reinforced with fibreglass. Therefore, one actually has two baths, one of acrylic and the second of fibreglass, which are then bonded together.
Acrylic is a far superior material for the production of sanitaryware and is accepted throughout the world as the most popular type of bath installed in homes.
Fitting A Geyser
With the valve correctly installed into the plumbing system (400kPa), no terminal fittings are opened and the system is filled with water and the pressure control valve is in the closed position. When a terminal fitting is opened on the outlet side, the downstream of the pressure control valve can fill a bath or a washing machine.
The water pressure drops on the outlet side (A2) causing a pressure drop under the diaphragm. The regulating spring defeats the lower pressure and forces the valve to open, allowing water to flow through the regulating seat, regulating the income mains from 700kPa to 300kPa while the water flows through the valve.
When the terminal fitting is closed the water pressure under the diaphragm builds up forcing the regulating spring back and the regulating seat shuts off.
A pressure control valve basically uses two components to operate, they are:
The big, regulating spring to open the valve and to regulate the pressure through the valve. The diaphragm to close the valve.
Pressure relief valve
What is the purpose?
To protect the hot water cylinder from over pressurising when water is heated. SABS specification 198-1992 operating pressures between 380 to 400kPa (400kPa system).
What is their application to hot water cylinders?
When cold water is heated it expands. When water expands in a concealed container, it creates pressure. When this pressure rises above the working rate of the hot water cylinder = 400kPa the pressure relief valve will open to discharge the excessive pressure. When the pressure inside the cylinder drops to below 400kPa the valve will close automatically.
This whole process is controlled by the thermostat that regulates the electric power to the element by switching on at low temperature and off when the water reaches the set temperature.
How does it work?
The incoming water mains are regulated by the pressure control valve in 400kPa system at 300kPa. This is the set pressure of the pressure control valve for a 400kPa hot water cylinder system. The pressure relief valve is set at 400kPa allowing a pressure gap of 100kPa between the set pressure of the pressure control valve (300kPa) and set pressure of the relief valve.
When the pressure inside the hot water cylinder rises, due to the heating process, the relief valve will open up when the pressure reaches 400kPa.
The expanded water is allowed to discharge to atmosphere preventing the water pressure from exceeding the system pressure.
A pressure relief valve must always be installed between the pressure control valve and the hot water cylinder. No non-return or stop valve must be installed between the hot water cylinder and pressure relief valve.
What does a pressure relief valve consist of?
The pressure relief valve consists of a forged DZR brass body with a stainless steel seat and a regulating spring with a seat washer combined into a cartridge. In the case of the pressure relief valve, the seat washer acts as the diaphragm that closes the valve. The Kwikhot pressure relief valve also incorporates a flushing mechanism for easy maintenance and a stainless steel seat for long life.
Vacuum relief valve (vacuum breakers)
What is the purpose?
To access air into the plumbing system when the water pressure drops below atmospheric temperature. SABS specification 198-1992 flowrate of 100 standard litres a minute. The vacuum does not exceed 9.0kPa negative.
What is their application to hot water cylinder installations?
A vacuum relief valve must always be fitted on a proper anti-siphon loop between the pressure control valve and the hot water cylinder. It will prevent back-flow (siphonage) from the hot water cylinder, when the inlet pressure drops below hot water cylinder pressure. By access air into the system, the siphon could break, which:
- Could drop the water level partly in the cylinder to the level of hot water cylinder inlet exposing the element and thermostat. This will cause the element to burn out, because the element and thermostat are not immersed in the water.
- Could drop the water level partly in the cylinder leaving the T&P valve’s (safety) probe not immersed in the water, which could cause a potential dangerous situation as the T&P valve will lag to open under extreme temperatures if the thermostat goes faulty. this could cause a flash steam explosion.
- Cause hot water to backflow and come out of the cold water fittings plumbed upstream of the hot water cylinder. This could result in scalding water users at cold taps.
- It sill prevent siphonage from hand showers lying in baths and washing machines, which could contaminate drinking water
- It could prevent cylinder implosion when the pressure drops below atmospheric, eg, the draw off of water exceeds the supply and by draining a cylinder.
- Prevents inter floor siphonage, where the geyser is serving more than one floor
Pressure control valve
Pressure reducing valves are of the pressure balanced type, which means that the set pressure (outlet) is unaffected by changes in the supply pressure (inlet). The set pressure to the hot water cylinder will remain constant.
Pressure control valve to be plumbed with the arrow on the body in the direction of water flow
Pressure control valve must be of the same pressure rating as the hot water cylinder.
100kPa hot water cylinder = 100kPa pressure control valve (label colour – blue)
200kPa hot water cylinder = 200kPa pressure control valve (label colour – black)
400kPa hot water cylinder = 400kPa pressure control valve (label colour – red)
600kPa hot water cylinder = 600kPa pressure control valve (label colour – green)
Distance between the pressure control valve and hot water cylinder pipe length:
100kPa system = 1m
200kPa system = 3m
400kPa system = 15m
600kPa system = 30m
Expansion relief valve
Expansion relief valve drain to be plumbed to a suitable visible place of discharge, not to be a potential nuisance and not into drip tray
Not to be interconnected with the safety valve, drain pipe
Must be piped at a decline
Must be protected against frost
Normal expansion is + 1,5% of volume of water heated
Safety valve drain pipe to be plumbed to a suitable place of discharge
Safety valve drain pipe never to be interconnected with expansion relief valve drainpipe
Safety valve drain pipe never to be plumbed into pvc sever or waste pipes
Safety valve drain pipe always to be metallic and
a minimum diameter of 20mm. Never use polypropylene or any other plastic pipe.
To prevent hot water cylinders from collapsing and syphonage, vacuum breakers must be fitted on inlet and outlet of a hot water cylinder. At a minimum of 300mm higher than the top of the hot water cylinder.
The connection for cold water supply to the geyser also allows for the hot water cylinder to be drained.
SABS specification 151 and SABS 0254, code of conduct call for the use of a drip tray. Kwikot highly recommend the installation thereof. All valves to be installed above drip tray.
all pipes must be flushed before commissioning of the system
all valves and terminal fittings to be removed prior to flushing
an inline strainer is to be fitted, where water quality cannot be guaranteed. The strainer cartridge should be removed before the pipes are flushed
do not install a stopcock or non-return valve between the hot water cylinder and the pressure-reducing valve.
Do not install a stopcock or non-return valve between the hot water cylinder and the vacuum breaker on the hot or cold side.
All valves must be plumbed in a serviceable position. Allow a minimum clearance of 100mm for removal of parts