plumbing

PLUMBING

Presentation on

Installation of a Domestic Cold Water Storage Cistern

Cold water Supply

At the end of this part you should be able to :

• State the requirements of pipes and fittings used in cold water systems.

• Explain the requirements of protecting systems against frost damage.

Cat boards are used to provide a safe area to walk and work on.

There is adequate lighting to be able to work safely.

You have a safe means of exiting the roof in an emergency.

You have fire extinguishing equipment to hand.

There is adequate ventilation.

If roof insulation is to be laid a protective mask must be worn.

Cold water – Health & Safety - Working in loft spaces

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Be on the look for vermin (Weal's disease).

Cold water – Health & Safety - Working in loft spaces

If working in existing or old roof spaces you should also:

Ensure you remove any old lagging to pipework is being altered and requires jointing with soldered fittings, many older types of pipe insulation are highly flammable.

Take care if old electric cables are in the work vicinity or are to be handled

Check for wasps or bees nests in the loft area.

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Cold water – Storage cistern requirements

The cisterns are available in square, rectangular or circular shapes, and are produced in black to prevent algae growth.

Because of their flexible material the base of the cistern MUST be fully supported and we shall look at the requirements for this next.

(Case study p34 in handout)

Cold water– Storage cistern requirements – Construction of a cistern stand

Storage cistern are usually located in the attic space, their installation has to meet the requirements of the Water Regulations.

Ceiling

Roof joists

Base bearer to span MINIMUM of three joists

Loft insulation

Stand legs

Brace

Deck

Check for levelGood practice to place sound proofing material, it also helps protect base of cistern against any sharp objects

If the cistern is to be laid on top of roof joists insulation can be removed to help protect cistern from frost damage.

Cold water – Storage cistern requirements – Construction of a cistern stand

Cistern base should span additional joists to help spread the weight of water being carried.

Timber or ply base should be used for the cistern base.

Chipboard must never be used as this is prone to disintegrate if it becomes damp.


Mark cistern float valve, overflow and outlet points.

Drill holes and fit valves and fittings.

Ensure swarf and debris are removed from inside the cistern.

Do not use oil based jointing compounds to make cistern connections as this can cause contamination to the water and may also react with some types of plastic storage cisterns.

Connect pipework.

Fill and test.


Cold water – Storage cistern installation requirements

Cold water storage cistern cannot be installed any old how

A drill used with proper hole cutters should be used NOT a heated piece of pipe

STORAGE CISTERN

Compression outlet connector, available in various sizes.

PTFE thread tape can be used IF required. No oil based jointing compound should be used.

Two plastic washers are used to seal the outlet connector to the cistern.

Washers go here

Cold water – Storage cistern installation requirements

SIDE OUTLETS

BOTTOM OUTLETS

Cold water – Storage cistern installation requirements – pipework connections

25mm to prevent debris entering pipework

25mm to prevent debris entering pipework

25mm

25mm

Cold water – Storage cistern requirements – Installation of cistern

Cold feed to cylinder 25mm from bottom of cistern

Cold feed top cylinder in A/C

Float operated valve

Rising main

Service maintenance valve

Close fitting lidVent Rubber grommet to

seal open vent from cylinder

Overflow with dip pipe fitted a min 25mm below level of float valve

Insulation jacket


Float operated valve

Insulation jacket

Installation kit

Cistern lid

Cistern

Service valve


Warning & Overflow pipes

Combined warning and overflow pipe with cisterns of 1000 litres or less

More than 1000 litres and a separate warning pipe is required

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50mm min

Screened overflow connection25mm min

Overflow pipe


It has to be stressed that there is a fundamental difference between a Warning Pipe and an Overflow Pipe:

A Warning Pipe

This is a smaller diameter pipe used to warn of an impending overflow. It is connected to the cistern lower than the Overflow Pipe.

This is designed to take the discharge from the cistern when the inlet valve is running full bore and prevent the inlet valve from becoming submerged.

Overflow Pipe

Both pipes to have screened outlets and terminate conspicuously preferably outside.Storage cisterns to have separate warning / overflow pipes from feed and expansion cisterns used for central heating.


50mm

25mm

50mm

Warning & Overflow pipe on cistern capacity over 1000 litres

If cistern supplies both hot and cold water supplies outlets must be positioned so that the hot water supply will run out before the cold …. Why ?


Feed to Domestic Cold Water

(indirect)

Domestic Hot Water Cold Feed

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AIRINGCUPBOARD

Incorrect pipeworkpositioning for rising main .. Why ?


AIRINGCUPBOARD

Correct pipeworkpositioning


Overflow pipes must be suitable to carry the water temperature that may discharge through them.

For example cisterns for solid fuel heating which may discharge boiling water should only be installed in copper.

Overflow must be one size larger than the supply it protects with the minimum size

22mm.

Must have a suitable fall to the discharge point and be well supported.


Water Regulations state

350mm minimum distance

Make sure that storage cisterns and pipework meet the minimum distances required by regulations, to prevent frost damage and allow servicing of cisterns.


STRAIGHT SERVICE VALVE FITTED TO

BALLVALVE

BENT SERVICE VALVE FITTED TO BALLVALVE

GATE VALVE FITTED TO CISTERN COLD WATER SUPPLY OUTLET


When the system has been filled and tested for leaks, water levels and performance the system should be flushed and cleaned.

Fit pipe and cistern insulation and labelling to valves.

DHWS CFE VALVE

CLOSE TO TURN OFF HOT WATER SUPPLY


Work book time


plumbing

Documents

cistern standstorage

base of cistern

cistern connections

cistern standcistern

cold water systems

water regulations

weight of water

cold water health safety