Module 2 Storage Cisterns

Question 1

What tap would not be supplied to the cistern?

Answer 1

The kitchen tap or drinking tap due to the possibility of stagnation

Question 2

What kn will a cistern give from 1 meter?

Answer 2

Each meter of water will give 9.8kn of water pressure at the tap

Question 3

Name 3 materials used to make cisterns?

Answer 3

Galvanised mild steel, plastic material, glass fibre sections

Question 4

Name two ways to prolong galvanised steel cistern?

Answer 4

Where holes are cut in galvanised steel cistern it is important to remove all the award as it can lead to serious corrosion due to electrolytic action 2, two coats of good quality paint on inside of cistern

Question 5

What jointing materials should be used on galvanised steel cistern?

Answer 5

Grommet jointing paste and back but and also nylon washers

Question 6

Define plastic cisterns?

Answer 6

They are strong and resistant to corrosion of all types vertically everlasting very hygienic and light in weight they do not cause none are they subject to electrolytic corrosion

Question 7

Name a few facts about plastic cisterns?

Answer 7

Quieter in filling, the come in square rectangular or circular, they are black to prevent algae growth, they must be fully supported

Question 8

What clearance must be at a min between a roof and a cistern?

Answer 8

A min of 350mm

Question 9

How are holes done in plastic cisterns?

Answer 9

By circular saw cutters

Question 10

What should never be done to make a hole in the plastic cisterns?

Answer 10

Never cut with hot pipes this will lead to failure around the joint

Question 11

How should the joints be sealed?

Answer 11

Plastic washers but no oil based pasted as it may cause the material to break down

Question 12

Glass fibre cisterns talk about them?

Answer 12

Is suitable for the construction of large cisterns built by using bolted sections generally provide over 5000 lets storage

Question 13

What must all cisterns have ?

Answer 13

Fitted with a tight cover from same material if possible and never wood as it can rot and not give a tight fit

Question 14

What is the definition of a cistern ?

Answer 14

It’s an open vessel designed to hold a supply of cold water which will have a free surface subject only to the pressure of the atmosphere

Question 15

What should be done to prevent water contamination??

Answer 15

The vent pipe should be sealed with a rubber grommet as it passes through the lid to prevent ingress of insects

Question 16

Why is it important to insulate the storage cistern??

Answer 16

1) in extreme cold weather it could freeze 2) if the water gets too cold it will require more energy to raise the temperature of this water in to hit water cylinder it supplies 3) in hot weather the water can become too warm and allow the multiplication of bacteria like legionella

Question 17

What will happen on an air tight cistern when water gets drawn away?

Answer 17

Air will need to come into the cistern to prevent a vacuum forming, a screened air vent should be provided to allow a clean supply of air to enter or exit the cistern

Question 18

To help prevent water contamination what should be done?

Answer 18

The over flow should have an integral filter to prevent ingress of insects

Question 19

Explain the nominal capacity?

Answer 19

The nominal capacity of a cistern is usually stamped or written on the side And indicates the amount of water it would hold if filled up to the top edge

Question 20

Explain the actual capacity??

Answer 20

The actual capacity refers to the amount of water measured from the base of the cistern up to the water line

Question 21

The explain the usable capacity?

Answer 21

The usable capacity is the amount of water which can be drawn off through the distribution pipe connections, this means the amount of water stored between the invert of the lowest connection and the water line

Question 22

Where should the position of the cistern be in roof spaces?

Answer 22

In domestic plumbing the cold water storage cistern is usually located in the attic or roof space

Question 23

Why is the final position of the cistern important??

Answer 23

Because of the weight of water must be taken into consideration 227litres weighs 1/4 ton

Question 24

How must the weight be distributed?

Answer 24

To prevent damage to the structure of the house, Because of this they should be located over load bearing walls with timber bearers beneath them

Question 25

Where should the cistern not be located?

Answer 25

Near the eaves because of the danger of frost damage from cold winds

Question 26

Where is the best place to locate the cistern?

Answer 26

Ideally it should be sited close to the chimney breast where it can benefit from the radiant heat emanating from it

Question 27

Fact?

Answer 27

When insulating the attic the space beneath the cistern should not be insulted, this will allow warm air in the form of conversation currents to rise from below

Question 28

What connections should all cisterns have??

Answer 28

1) rising main supplying the ball valve 2) overflow connection 3) cold water distribution pipes 4) cold water feed pipe

Question 29

Name a few things an overflow pipe should be?

Answer 29

It should be one size larger than the supply pipe, located 40mm below the ball valve connection,

Question 30

Where should the overflow finish?

Answer 30

It should be in a conspicuous position which will alert the owner to a leak, ideally it should be in a position where it will cause a nuisance not over a doorway as it can dangerous in frosty weather

Question 31

On larger cisterns where would the overflow pipe go?

Answer 31

It’s not practical to have it over a window and therefore the overflow which may be 2” or larger will be directed to a gully ( cistern over 1000lt )

Question 32

It is necessary to run a smaller diameter pipe of 1/2 or 3/4 to a conspicuous position to warn the householders this is know as the WARNING PIPE

Answer 32

A domestic cistern overflow is both overflow band warning pipe combined

Question 33

Where should the connections for the distribution pipes be located?

Answer 33

In such a way that silt cannot be drawn into the pipe ( 40mm above bottom)

Question 34

Where should cylinder feeds be located?

Answer 34

Placed above the distribution pipes 25mm to prevent possible scalding in the even of mains failure

Question 35

Support for pipe work explain?

Answer 35

They should be adequately supported and connect at right angles to the cistern be all to prevent fatigue of the cistern around the joint area and prevent possible premature failure

Question 36

What is the back plate?

Answer 36

It is used to protect the cistern wall from fatigue caused by continuous movement of the ballvalve, it can also help prevent water hammer

Question 37

How is stagnation prevention explain?

Answer 37

Distribution and feed pipe work should always be connected to the opposite end to the mains inlet to allow water to move across the cistern and prevent pockets of stagnant water , cisterns should not be oversized

Question 38

What is important when installing two or more cisterns?

Answer 38

Each cistern must have a mains water inlet to prevent the top later becoming stagnant each cistern must have an over flow and an opposite side exit on each cistern for cold distribution and cold feed pipe work to prevent stagnation