Information

Advanced Cold Water

This site is designed to give an overview of advanced cold water requirements to use when designing cold water systems©

Direct boosted cold water supply for multi occupancy dwellings

As we know water will only rise so high on its own for example; 1 bar of pressure will rise 10 metres in height. To overcome this we require some assistance in the form of a pump. You need to know how high the water will travel vertically if the unit is in bar or kPa. Above is an image of a boosted cold supply and a table outlining the basis of the conversion from bar-metres of water and bar - kilopascals (kPa)

Direct cold water supply for single occupancy dwellings

The image shows a simple direct cold water system that is used on millions of homes around the UK that have a reasonable incoming mains pressure. The cold supply will offer mains cold water to every appliance in the dwelling meaning every outlet has clean wholesome water at every outlet.

This particular image shows a system that has a CWSC suppluing the hot water storage vessel.

Indirect boosted cold water supply for multi occupancy dwellings

As we know water will only rise so high on its own for example; 1 bar of pressure will rise 10 metres in height. To overcome this we require some assistance in the form of a pump. You need to know how high the water will travel vertically if the unit is in bar or kPa. This image shows an Indirect boosted supply, this is the preferred installation method of the water undertakers as it is not putting excessive demand on the mains network at peak demand. This is due to the 'Break Cistern' forming part of the installation of the Indirect boosted cold water supply.

Indirect cold water supply for single occupancy dwellings

The image shows a simple Indirect cold water system that is used on millions of homes around the UK that have a poor incoming mains pressure. The cold supply will offer mains cold water to only one appliance in the dwelling meaning every other outlet and appliance is fed from the CWSC

This particular image shows a system that has a CWSC suppluing the hot water storage vessel and the upstairs appliances, with the mains supply feeding the downstairs appliances (usually kitchen sink only) and a rising main to the CWSC.

Let us have a check on our progress so far...

Components

Components a small selection

Flow limiting valve used to limit the flow rate to an appliance in litres per minute.
Cistern-miser used to fill the cistern with water above a urinal, when it senses different hydraulic pressures. Then allowing the urinals to be flushed with water from the cistern.
Pressure reducing valve, used and set to a pre determined static pressure to comply with component pressure limits.
Infra red taps, used to conserve water and avoid contact with the outlet from multiple persons. sensor driven, connected to a solenoid valve that recieves its temperature controlled water from a blending valve.
Infra red urinal control, this device controls the inlet of water to a cistern above the urinal. Activating when there is movement in the room only conserving water.

Filtration

A couple of examples of filtration used to clear out impuruities in a water supply

More checks on knowledge

Backflow prevention

Backflow - a small range

Zoned protection, using a RPZ valve to protect the wholesome water when connected to an industrial process. RPZ located before the industrial process protecting the wholesome water.
Whole site protection, using an RPZ valve to protect the whole site located on the incoming mains supply.
Back pressure, low pressure in the mainscan lead to the pressure in the property becoming greater leading to water going back into the local main.
AUK1 found already within an appliance
AG air gap, featured within the cistern CWSC/WC
AUK2 air gap between the spillover level and the outlet on a WHB/Bath
AUK3 air gap found on a kitchen sink betweenthe spillover level and the outlet.
AA air gap inlet of water has a gap before the storage cistern

Knowledge check #003

Water main sizing

Firstly before we look at the content and how it applies to dwellings let us clarify what each term actually means.

Mains supply- is any supply of water that comes from the water undertakers main. This is fed from a treatment plant/pumping station and is then fed directly to the water main network.
The size of the Trunk main will vary in diameter depending on the purpose of the main and likely demand for the supply

Quick question

Why do you think that the water main network is in a complete circuit, rather than just running from source to the end of the line?

Sources of water that service our water mains and private supplies

List is not exhaustive but it begins to show a range of sources that supply water to dwellings

Quick activity

The following towns all have a water supply, using content already covered in the session Identify and State the size of the trunk main required for the town. You have 15 minutes to complete this task. Look on Google to begin with for how many people live in each town.

Kearsley
Farnworth
Westhoughton
Blackrod

Answer to activity

Now we look at the Private water supplies

Private water supplies- A private water supply is defined as any water that is NOT provided by a water undertaker. It is not connected to any part of the water mains network, and as such, now water rates charges are applied.

Surface water - springs and streams

Before extracting, customer must first obtain a license from the Environment Agency.

Not protected, like groundwater, from contaminants including:

human waste

animal waste

industrial waste.

Solids washed downstream during heavy rainfall.

Will need to be settled or screened off before pump intake.

Submersible pumps ideal for these applications.

Quick question

There are two types of pumps for a private water supply to get the water from source to dwelling, a submersible pump being one and the other is an above ground pumping set. What do you think is the main advantage of a submersible pump over an above ground pumping set?

Fluid risk categories

Water is supplied and is meant to be fit for human consumption. therefore there are 5 categories of water which can be seen below

When installing and designing a plumbing system it is vital that the designer and the installer have an awareness of how water can become contaminated and how to prevent the water that maybe contaminated being supplied to an outlet that could cause harm to anyone who may come into contact with it or harm the wholesome supply.

Quick activity

I have a scenario for you. Imagine you are a plumber who has been asked to install a set of taps on a wash hand basin in a vet's surgery. The wash hand basin is used by the vet to clean their hands after they have examined and treated the animals. From the list of back-flow prevention devices below select which you feel would be appropriate to prevent any contamination of the wholesome supply.

Single check valve-used to prevent category 2 water mixing with category 1
AUK1 air gap-installed in the appliance by manufacturer
AUK2 air gap-used to prevent category 3 water mixing with category 1
RPZ valve-used to prevent industrial processes mixing with category 1
AUK3 air gap-used to prevent category 5 from mixing with category 1

Quick check on your progress

Have a go at the questions on the flipped classroom

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