Cold Water Supply

Muscroft: Plumbing 2nd ed - Curriculum Support Pack

Unit 5 Cold Water Supply

UNIT 5 COLD WATER SUPPLY



Introduction

These slides are intended to support tutor delivery of the Plumbing 6129 level 2 Technical Certificate and should be used in conjunction with the second edition of ‘Plumbing’ by Steve Muscroft.

The slides are based on each unit in the book, and are designed to provide ‘samples’ for each topic area, they are not presented as a complete set of slides but as a ‘starter’ for tutors to build up their own presentation package.



This unit covers:

Cold water supply and treatment:– Regulations– Collection and storage of water– Water distribution– Water treatment– Service and mains connection– Requirements of service pipework– Water meters

Domestic cold water supply in domestic dwellings:– Types of systems, direct and indirect– Scale inhibitors and conditioners – Requirements of cold water storage cisterns– Frost protection



Physical forms of water



The rain cycle



Ferrule and goose neck



Details from the mains to the internal stop valve



Internal stop valve

•What’s the yellow and cable for?

•What is the white substance above the compression nut on the stop valve?



Typical water meter



Internal stop valves

Combined stop valve and drain tap



Water mains pressure

Mains water pressure is measured in bars. Supply pressure is important because it needs to satisfy the demands of the consumer, as well meeting appliance specifications that require a minimum water pressure to enable them to operate to effectively, an example being instantaneous showers or water heaters.

The operating pressures for such appliances should be included in the manufacturer’s instructions. The Water Supplier is responsible for the water mains delivery pressure to the building, so if it’s poor they would need to be advised.



Water flow rate can be measured at the tap by using a flow meter device called a weir gauge. Alternatively this can be carried out by using a container with a known capacity e.g. measuring beaker used for cooking, and with the tap full open timing how long it takes to fill the container and then calculating the flow rate per minute in litres per minute.



There are several different methods for reducing the build up oflimescale in domestic plumbing systems, including:

– Base exchange softeners – Electrolytic Scale Inhibitors– Magnetic Scale Inhibitors – Digital Electro Magnetic conditioners

Electrolytic

Magnetic



Water system types: Direct system



Water system types: Indirect system



Requirements for cold water storage cisterns (CWSC): The CWSC is a very important part of a domestic cold water system, and as such is well covered by the Water Regulations. The following illustration shows a CWSC that fully meets the Water Regulations requirements of Schedule 2: paragraph 16 (4) for cold water storage cisterns installations.



Cistern connections and control valves

Portsmouth valve




Diaphragm valve




Diaphragm equilibrium float valve



Servicing valves

Three different types of servicing valve where do you think eachmight be used?



Use of check valves

The following list shows some typical applications where the Water Regulations require single and double check valves to be installed.

Single check valves– Connected prior to water softener– Unvented heating systems– Supply to wet sprinkler system – Downstream of meters and pressure reducing valves (no specific

regulation but essential for correct operation of equipment)



Use of check valves continued

Double Check Valves – Supply to hose taps – Supply to standpipes – Pipe connection to cisterns using part 1 float valves– Supply to shower fitting

Shower Check Valves – Supply to shower spray head where shower hose pipe is

unconstrained e.g.. air gap requirement cannot be guaranteed.



Warning and overflow pipes

What is the purpose of a warning and overflow pipe?



Frost protection

Requirements for suspended timber floors



Hose union bib tap and requirements for external stand pipe



Details of insulated cold water storage cistern

Unit 5 Cold Water Supply Activity 5.1 What do you think are the main objectives of the regulations? There are five listed in the regs, starting with ‘preventing the contamination of a water supply’. Write them down on separate sheets of paper and put them in your portfolio, you can find the answers in the book. 1. 2. 3. 4.

Muscroft – Plumbing: Curriculum Support Pack: classroom handouts

Activity 5.2 Water can be found in three physical forms, what do you think they are? We’ve given you one answer; jot down the other two in your portfolio. Check your answers in the book. 1. 2. Liquid - as water. 3.


Case study Figure 5.5

Leslie has been asked to check that the installation in figure 5.5 is installed correctly. Leslie consults the regulations and makes the following notes as a cross check. • The supply pipe or distributing pipe that’s providing water to individual dwellings

must be fitted with a conveniently located stop valve to enable the supply to be shut off. The minimum permitted size for a cold water service into a building is 15mm diameter.

• Where a cold water supply pipe enters a building via a duct, the pipe duct must be

sealed at both ends; this is to prevent any gases or vermin entering the building. • In order to protect against frost damage, mains and service pipes should be at

least 750 mm beneath the surface of the ground. This is a requirement made under the Water Regulations Schedule 2, paragraph 7 (4)

• The maximum depth of cover over the pipe should not exceed 1.350 metres, as

this would prevent ease of access • Metallic pipes, such as copper should be protected against possible corrosion from

soil, particularly where acidic soils exist. This can be achieved by: - Using plastic coated pipe - Wrapping the pipe with a suitable protective wrapping - Installing the pipe inside a duct, sealing the ends of the duct on final

completion.


Activity 5.3 Why not see if you can try and locate the external stop valve where you live? This is used to isolate the supply to a dwelling, and plumbers may be required to locate it. The stop valve within the box should be accessible, i.e. clean from debris etc. Just locate it; please don’t do anything with it!!


Activity 5.4 Take a close look at the two diagrams and have another read of the text. Have a think about what the advantages and disadvantages might be for both systems. Jot down your thoughts on separate sheets of paper and include them in your portfolio. A suggested answer is in the book.


Activity 5.5 What do you think is the main advantage of fitting servicing valves? Write your answer on a separate sheet and include it in your portfolio before checking against the suggested answer in the book.


Case study Leslie has been called out to a job to check that a CWSC installation conforms to the water regulations. If the float operated valve becomes defective, the warning pipe must be capable of removing the excess water, preventing the valve from being submerged and the cistern from spilling over, so Leslie makes a note of the following points to check out. • Warning pipes should have a minimum diameter of 19mm, or be a least one size

larger than the inlet pipe. They must be fitted with a screen or filter to prevent insects or vermin getting in

• Warning/ overflow pipes must be constructed from rigid, corrosion resistant

material. Flexible hose connections are not allowed to form part of the pipe. • Warning pipes from central heating feed and expansion cisterns must be kept

separate from those from cold water storage cisterns. • Warning pipes must fall continuously from the cistern to the point of discharge. • It’s OK to joint two or more warning/ overflow pipes, from similar types of cisterns

to form a common warning pipe, providing that the discharge is visible and that one cistern doesn’t discharge into the other.


Activity 5.6 The illustration above shows an external stand pipe installation. Can you identify the key design features? Write down your findings for your portfolio and check them out in the book.


5.1 Test yourself 1. What regulations cover the requirements of the cold water supply to a

domestic dwelling? 2. The regulations cover five main objectives, state one of these objectives. 3. When water freezes, by what percentage does it expand? 4. Which type of water is most likely to cause the build up of limescale in water

systems when heated above 65-70°C? 5. Name two underground sources from where water can be obtained.

6. Briefly describe what is meant by the term ‘the rain cycle’.


5.2 Test yourself 1. What are the minimum and maximum depth measurements for under

ground water service pipes? 2. List the two methods of treatment used for reducing limescale in hard

water areas

3. State two main purposes of stop valves and servicing valves on installation pipework.

4. Give two example of where a double check valves might be used 5. The paragraph below describes the difference between a direct and

indirect cold water system, fill in the missing words. All the pipes to the draw off points (kitchen sink, bath, wash hand basin, wc, etc) in a …………..system are taken …………..from the ………….-……….and operate under …………..pressure. With the ………….system, one outlet usually the kitchen sink is fed directly from the rising main, before it continues to supply the ………….. The remaining draw off points are fed from this source. 6. State two main forms of frost protection used on cold water installations.


Multi-choice end assessment Time available to complete all questions: 15 minutes Please tick the answer that you think is correct. 1. From which of the following would find the legal requirements for the installation of

cold water services? a. British Standards b. Building Regulations c. Construction Regulations d. Water Regulations 2. What is the minimum depth for an underground cold water service pipe? a. 350mm b. 550mm c. 750mm d. 1350mm 3. What is the maximum depth of an underground cold water service pipe? a. 350mm b. 550mm c. 750mm d. 1350mm 4. Which of the following items of equipment would be used to determine that a cold water supply to a dwelling would be adequate to serve the plumbing appliances? a. Flow meter b. Water meter c. Manometer d. Pressure gauge 5. The most common use of type ‘B’ compression fittings is: a. On internal cold water supply pipework b. To isolate float operated valves c. On Underground service pipework d. To drain down the CWSC 6. Drain taps on internal service pipework should be located: a. Immediately above the stop valve b. Immediately below the stop vale c. A minimum of 300mm above the stop valve d. A drain tap should not be fitted to the internal service pipe


7. The minimum capacity of an indirect cold water storage cistern in a domestic dwelling should be:

a. 75 litres b. 115 litres c. 230 litres d. 415 litres 8. The minimum capacity of an direct cold water storage cistern in a domestic

dwelling should be: a. 75 litres b. 115 litres c. 230 litres d. 415 litres 9. A weir gauge would be used to measure the: a. Water pressure at a tap b. Water flow rate at a tap c. Depth of the CWSC d. Temperature of the water in the CWSC 10. On an indirect cold water system, the cold feed outlet from the CWSC to the

domestic hot water cylinder should be? a. Level with the cold distribution outlet b. Lower than the cold distribution outlet c. Located at the base of the cistern d. Higher than the cold distribution outlet 11. On a cold water system conforming to the Water Regulations, which of the

following should be turned off to isolate the WC float valve? a. Supply stop valve b. Appliance service valve c. Water supplier’s stop valve d. Distributing service valve 12. In areas where the water supply is poor during periods of peak demand, what type of system would usually be specified for a domestic dwelling? a. Direct Cold Water System b. Boosted Cold Water System c. Indirect Cold Water System d. Secondary Cold Water System


13. An overflow pipe as well as a warning pipe is required on cisterns with a

capacity in excess of: a. 115 litres b. 230 litres c. 1000 litres d. 1250 litres 14. On a cold water storage cistern with a capacity of 115 litres, what is the

required distance between the water level and the outlet of the warning pipe?

a. 25mm b. 35mm c. 40mm d. 45mm 15. In a direct system of cold water supply, the purpose of the cold feed pipe is

to: a. Replace the water to the hot water storage cylinder as it is drawn off b. Provide a means of filling the cold water storage cistern from the mains c. Supply the water to the various cold water outlets within the system d. Prevent the cistern from overflowing should the float operated valve fail 16. On a new cold water system conforming to the Water Regulations, which of

the following should be turned off to isolate the float valve to the cold water storage cistern?

a. Appliance service valve b. Supply pipe service valve c. Water supplier’s stop valve d. Distributing service valve 17. The Water Regulations require that the water temperature in CWSCs and cold

water pipework should not exceed: a. 20ºC b. 21ºC c. 23ºC d. 25ºC


18. Where a CWSC is located in the roof space of a dwelling and the space beneath it contains thermal installation, what action should a plumber take?

a. Increase the depth of insulation by 50mm b. Increase the depth of insulation by 100mm c. Decrease the depth of insulation by 50mm d. Remove the insulation from beneath the CWSC 19. The minimum unobstructed space for a cistern of a 1000L or less is: a. 250mm b. 350mm c. 400mm d. 450mm 20. The purpose of pipework insulation material is to: a. Prevent the water in the pipe from freezing in cold weather b. Protect the pipework and fittings from accidental damage c. Retain the heat energy in the pipe to reduce the risk of freezing d. Insulate the pipework should it come into contact with a live cable


Answers to activities and test yourself questions Answers to Activities Activity 5.1 The objectives of the regulations are to: • Prevent the waste of water i.e. (faulty appliances, poor maintenance, leaking fitting

e.g. dripping tap) • Prevent misuse of a water supply i.e.(the use of energy in the mains supply to

provide motive power, or for the generation of electricity) • Prevent undue consumption of water i.e. (fittings and appliances that use more

water for the purpose they were designed) • Prevent Erroneous measurement i.e.(tampering and interference with the

measurement of water passing through the meter e.g. fiddling the meter) Activity 5.2 The physical forms of water are:

• Solid -as ice. • Liquid - as water. • Gas - as steam or vapour.

At atmospheric pressure, and at a temperature of between 0ºC to 100ºC water will be found as a liquid. At a temperature of 0ºC or below, water changes to ice, expanding immediately in volume by 10% (hence the reason water pipes burst when frozen) When subject to a temperature above 100ºC, water will change to steam, expanding in volume by approximately 1600 times.


Activity 5.3 Direct systems offer the following advantages:

• Cheaper installation costs, due to less pipework being required.

• Drinking water is available from all draw off points.

• Water storage will only be required to feed the hot water storage vessel, so the storage cistern will be smaller in size. The minimum requirement being 115 litres.

The disadvantages are:

• The higher water pressure may make the system suffer transmission noise e.g. water hammer.

• No reserve of water if the mains or service supply is shut off for a period of time.

• Precautions must be taken so to prevent back siphonage occurring (water

flowing back) or fowled water from appliances, contaminating the mains supply. Remember this is a requirement of the Water Regulations. (you may have missed this one)

The indirect system offers the following advantages:

• Lower delivery pressure reduces the risk of system noise.

• Lower demand on the water main at peak periods.

• There’s a reserve supply of water should the mains supply be turned off, for a period of time.

• The wear and tear element on taps and valves is reduced, due to the lower

delivery pressure. The disadvantages are:

• Higher installation cost for larger storage cistern and additional fittings and pipework.

• Larger diameter of pipework required, to appliances.

• Additional structural support will be required for the increased weight of a larger

storage cistern.

• The storage cistern will require an increased space or area (minimum capacity is 230litres).

• Increased risk of damage from frost.


Activity 5.4 What do you think is the main advantage of fitting servicing valves? The main advantage is that it enables maintenance work to be carried out to the cistern without turning off the whole water supply. Activity 5.5 The illustration above shows an external stand pipe installation. Can you identify the key design features? Write down your findings and check them out at the end of the unit. The installation is fitted with a drain tap; which allows the pipework to be drained once the stop tap has been turned off. The minimum depth of 750 mm below ground still applies to installations of this type. The double check valve fitted to protect against backflow contamination to the water supply meets the requirements of Schedule2: paragraph 15 (1) of the Water Regulations.


Test yourself answers 5.1 Test yourself answers 1. Water Supply (Water Fittings) Regulations 1999 2. One from; • Prevent contamination of the water supply • Prevent the waste of water • Prevent misuse of the water supply • Prevent undue consumption of water. • Erroneous measurement 3. 10% 4. Hard water 5. Two from: • Wells • Artesian wells • Springs 6. Water evaporates from rivers, lakes, the sea and the ground which in turn forms

clouds. Clouds contain water vapour which, when the climatic conditions are right, condense and fall as rain.

When rain falls to the ground, some runs into streams, rivers, and lakes, the remainder soaks into the ground, where it collects temporarily and eventually evaporates.

5.2 Test yourself answers 1. 750mm min and 1350mm max 2. Base exchange water softeners

Electrolytic scale inhibitors or Electromagnetic conditioners 3. Isolate the water supply

Permit maintenance and servicing to be carried out on systems 4. Two examples from:

- Supply to hose taps - Supply to standpipes - Pipe connection to cisterns using part 1 float valves - Supply to shower fitting


5. The paragraph below describes the difference between a direct and

indirect cold water system, fill in the missing words. All the pipes to the draw off points (kitchen sink, bath, wash hand basin, wc, etc) in a direct system are taken directly from the rising main and operate under mains pressure. With the indirect system, one outlet usually the kitchen sink is fed directly from the rising main, before it continues to supply the CWSC. The remaining draw off points are fed from this source. 6. State two main forms of frost protection used on cold water installations.

Pipe, components and cistern insulation Trace heating


Cold water storage cisterns Cisterns storing water for domestic purposes should be: • Fitted with a supply float operated valve to maintain the correct water level in the

cistern. The float valve must be fitted as high as possible within the cistern. It must comply with the requirements of BS1212 part 2 or 3, in order to maintain an air gap and prevent the possibility of back siphonage into the incoming supply. This meets the requirements of the Water Regulations Schedule 2 paragraph 16 (1). Float valves complying with BS 1212 Part 1 valves may be used, providing it has an adjustable float lever connection.

• Fitted with service valves on inlet and outlet pipes for maintenance or servicing

purposes and for shutting off the flow of water in a pipe to a water fitting.

This meets the requirements of the Water Regulations Schedule 2 paragraph 16 (3).

• Covered with a securely fixed lid, that is not air tight, but excludes light or insects.

The lid shall incorporate a screened air inlet, and where the vent pipe from the hot water cylinder passes through it, and be appropriately sleeved.

• Fitted with a screened overflow/ warning pipe to warn of overflow discharge. The

overflow pipe must have a minimum internal diameter of 19mm, and in all instances be greater in size than the incoming inlet pipe.

• Installed so as to minimise the risk of contamination of the stored water. The

pipework connections must also be positioned to allow the water to circulate freely preventing the possibility of stagnant water.

• Insulated to protect against frost and freezing, and to prevent heat gain of the

stored water. Keeping the water temperature below 20ºC will restrict the possibility of microbiological growth bacteria such as Legionella.

• Fully supported on the whole of its base area. This will prevent undue stress on

pipe connections and distortion of the cistern when filled with water, which could result in leaks.

• Installed in an accessible position, to allow ease of maintenance and for cleaning

purposes. There must be a minimum clearance height of 350mm above the top of the cistern.

In order to reduce the risk of water-borne diseases such as Legionella in water storage systems, it’s recommended that the outlet connection be positioned as near as possible to the bottom of the cistern. This allows any small particles that may be present to pass through the system, preventing an unhealthy build-up of sediment at the base of the cistern.


Use of check valves

• Single Check Valves - Connected prior to water softener - Unvented heating systems - Supply to wet sprinkler system - Downstream of meters and pressure reducing valves (no specific regulation but essential for correct operation of equipment)

• Double Check Valves

- Supply to hose taps - Supply to standpipes - Pipe connection to cisterns using part 1 float valves - Supply to shower fitting

• Shower Check Valves

- Supply to shower spray head where shower hose pipe is unconstrained eg. air gap requirement cannot be guaranteed.


Sources of Information We have included references to information sources at the relevant points in the text; here are some additional contacts that may be helpful.

• Pegler limited St Catherine’s Avenue Doncaster South Yorkshire DN4 8DF Tel: 01302 560560 Website: www.pegler.co.uk

• Yorkshire Fittings

Head Office PO Box 66 Leeds LS10 1NA Tel: 0113 270 1104 Email: [email protected]: www.yorkshirefittings.co.uk


Muscroft Plumbing – Curriculum Support Pack: Lesson Plans

Lesson Plan Tutor: Programme Area: Plumbing

Room Number: Date:

Course code & title: 6129 City & Guilds basic certificate in plumbing

Session Title: 8 Practical training and assessment Overall aims of session • Introduction to maintenance of valves and fittings. • Demonstration of re-washering taps, float valves and repairing siphons.

Session objectives At the end of the session learners will be able to: • Identify types of tap. • Re-washer a float valve. • Continue training tasks.

Assessment strategies How will you & the learners know they have (fully/partly/not) achieved the objectives? Observation of learning activities. Peer assessment. Assessment with verbal and written feedback.

Health & safety Have you checked the room & resources before the lesson?

Yes No

Note any issues that need to be passed on to the College H&S officer or Campus Services

Equality & Diversity

How are you ensuring your session promotes E&D/is inclusive?

Students will work from practical training pack and formal assessment portfolio. All students will be given equal opportunity to complete the set exercises.

Differentiation (include roles of any Learning Support Assistants) Students will be allowed to work at their own speeds. Tutors are to ensure that all students are supported and encouraged to progress.

Timing (minutes)

Activity Resources (including ILT) Interaction Method of assessment (I, F or S *)

30

Tutor presentation (Identifying and repairing common faults on plumbing systems)

Taps, float valves and syphons

Demonstration

75

Training tasks as set out within the training portfolio

Training pack

Individual practical training

Break

30

Tutor presentation (Repacking glands, other symptoms and faults that may occur)

Various fittings and scenarios

Demonstration

75

Training tasks as set out within the training portfolio

Training pack

Individual practical training

Evaluation of session What went well? / How have I gained this feedback? / How will you share this with colleagues? What would you change for next time? * I = Initial Assessment, F = Formative Assessment, S = Summative Assessment

Muscroft Plumbing – Curriculum Support Pack: Lesson Plans

Cold Water Supply

Documents

Transcript of Cold Water Supply