Cold Water Storage Cisterns Flashcards
Define a cold water storage cistern? (Cwsc)
It is defined as an open topped vessel designed to hold a supply of cold water.
What is the name given too a vessel used to store cold water in the attic?
Cold water storage cistern
Should it ideally be fitted at high or low level? Give a reason for your answer
It should be fixed as high as possible to give adequate pressure flow
List 3 materials used it the manufacture of cold storage cisterns?
Galvanised mild steel
Plastic materials
Glass fibre sections
List 3 reasons for fitting a cover on a cold water storage cistern?
To prevent the access of dirt, dust, vermin or light
Is it ok to fit a wooden cover?? Explain your answer
Wooden covers are not ideal as wet rot can occur and a tight fit is not possible
Should you drink the water from a cold water storage cistern?
No you can’t due to the possibility of stagnation
Give 3 reasons why the cold water storage cistern should be insulated?
1) Water could freeze in cold weather
2) if the water gets too cold it will require more energy too raise the temp of this water in the hot water cylinder it supplies
3) in hot weather the water can become too warm and allow the multiplication of bacteria
What is the purpose of screening vents?
the purpose of screening vents are to stop dirt particles getting inside the cistern
What is galvanising of cold water storage cisterns?
When it is dipped into zinc
List two methods of good practise that can prolong the life of a galvanised cold water storage cistern?
Removing the swarf and spreading two coats of good quality bituminous paint on the inside of the cisterns
Give 3 advantages of using plastic cold water storage cisterns over galvanised?
They are strong and resistant to corrosion
Virtually ever lasting
Very light in weight
Is it ok too cut holes in plastic cisterns using hot pipework?
No because it will lead to failure around the joint
Can jointing compound be used on plastic cisterns? Give an example for your answer?
No because it softens the materials and makes it break down
What is a suitable material for jointing to a polythene cistern?
Plastic washers
Why are plastic cisterns black?
Too prevent algae growth
How are holes cut in a plastic cold water storage cistern?
They are drilled with a holesaw
Can boss White be used on a polythene cistern?
No it cannot
We’re are glass fibre cisterns used?
We’re more amounts of water is able too be stored like hotels
What is the actual capacity of a cold water storage cistern?
The actual capacity refers to the amount of water measured from the base of the cistern up to the water line.
What is the nominal capacity of a cold water storage cistern?
The nominal capacity indicates the amount of water it would hold if filled up too the top edge.
What is the usable capacity of a cold water storage cistern?
The usable capacity is the amount of water which can be drawn off through the distribution pipe connections.
What is the approximate weight of a polythene cistern with an actual capacity of 500 litres?
Half a ton
Where should the ball valve be fitted on a cold water storage cistern? Give reason for your answer?
Ball valves should be fitted as high as possible to gain the maximum storage of water
What is the purpose of an overflow pipe?
The purpose of an overflow pipe is too prevent floods
Where should the overflow pipe be fitted on a cold water storage cistern? Give reason for your answer?
It should be located 40mm below the ball valve connection to ensure the ball valve will never become submerged
We’re should the cold distribution be fitted on a cold water storage cistern? Give a reason for your answer?
65mm from the bottom of the cistern and to prevent possible scalding in the event of mains failure
Where should the feed too the cylinder be fitted on a cold water storage cistern?
It should be fitted just above the cold water feed
What size should an overflow pipe be?
It should be one size larger than the cistern supply pipe
Why is the ball valve sites 40mm above the overflow?
If it becomes in contact with the overflow it can cause back siphonage
What is the purpose of a ball valve backplate?
It is used to protect the cistern wall from fatigue
How should two or more cisterns be connected?
When connecting two or more cisterns each cistern must have a mains water inlet to prevent the top layer becoming stagnant each cistern must have an overflow and an opposite side exit on each cistern
How is stagnation prevented on a single cold water storage?
All cisterns should be installed to best practise to prevent stagnation
