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42 Cards in this Set
- Front
- Back
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What is the name given to the vessel used to store cold water in an attic? |
A cistern |
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Define a cold water storage cistern? |
Open tapped vessel designed to hold a supply of cold water, which will have a free surface subject only to the pressure of the atmosphere. |
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Should it be fitted at high or low level? |
Should be fitted as high as possible to give adequate pressure flow. |
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List 3 materials used in the manufacture of cold water storage cisterns? |
Galvanised mild steel, plastic materials and glass fibre. |
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List 5 reasons for fitting a cover on cold water storage cistern? |
To prevent contamination, prevent access of dirt, dust, vermin and light getting in. |
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Is it okay to fit a wooden cover? |
No. They are not ideal as we trot can occur and they are not tight fit. |
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Should you drink the water from cold water storage cistern? |
No |
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Give 3 reasons why cold water storage cistern be insulated? |
Extreme cold water the water could freeze. If water gets to cold will require more energy to raise temperature and in hot weather water can become too warm allow for the growth of legionnella. |
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What is the purpose of screening vents and overflows? |
To prevent ingress and insects. |
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What is galvanising of cold water storage cylinder? |
Dipped into bath of acid to remove grease and scale. Dipped into bath of molten zinc then coated with corrosion resistant skin of zinc. |
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Do galvanised mild steel cisterns need a continuous flat Base under them for support? Why? |
No. Because they are self supported and can sit directly on the timber. |
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List 2 methods of good practice that can prolong the life of a galvanised cold water storage cistern? |
Remove all the swarf and apply bituminous paint on inside of cistern. |
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List 3 advantages of using plastic cold water storage cisterns over galvanised? |
Quieter in filling, does not suffer from electroylic corrosion and it's strong and resistant from corrosion. |
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List 1 advantage of using galvanised cold storage cisterns over plastic? |
Galvanised cisterns are self supporting and plastic cisterns need to have support. |
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Is it ok to cut holes in plastic cisterns using hot pipework? |
No. Because it will lead to failure of the pipe. |
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Can pipe jointing compound be used on plastic cisterns. |
No. Because this softens the material and causes it to break down. |
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What is a suitable material for jointing to a polyethylene cistern? |
Plastic. |
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What is the minimal size of CWSC required for am indirect system in a house containing up to 3 bedrooms? |
212 litres |
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What is the minimal size of CWSC required for an indirect system in a house containing up to 4 bedrooms? |
340 litres |
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What is minimum size of CWSC required for direct system? |
They should be at least the same actual capacity as the hot water cylinder. |
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Why are plastic cisterns black? |
To prevent the growth of algae. |
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How are the holes cut in a plastic cold water storage cistern? |
Circular saw cutters |
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How are the holes cut in a galvanised cold water storage cistern? |
The holes are cut by a tank cutter or an expanding bit. |
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Can boss white be used on a polyethylene cistern? |
No |
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Where are GRP used? |
Constructed in buildings after construction has taken place. |
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How are GRP cisterns insulated? |
Twin walled |
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What is the actual capacity of a cold water storage cistern? |
Is amount of water measured from the Base of the cistern up to the water line. |
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What is the nominal capacity of a cold water storage cistern? |
Capacity of cistern usually stamped/written on its side. Indicates amount of water it can hold. |
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What is useable capacity of cold water storage cistern? |
Is amount of water which can be drawn off through pipe connections. Means amount of water stored between the invest of the lowest connection and the water line. |
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List 6 good practices to observe when installing a cold water storage cistern? |
Overflow pipe should be one size larger than cistern supply pipe, located 40mm below ball valve connection, overflow should be below ceiling to avoid freezing, backplate should be used to protect cistern wall from fatigue, cylinder feeds placed 25 mm above distribution pipes and connections taken from side of cistern 40mm above the bottom. |
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Where should ball valve be fitted on a cold water storage cistern? |
Located 40mm above overflow pipe. |
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What is purpose of an overflow pipe? |
Stops back siphonage |
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Where should overflow pipe be fitted on CWSC? |
Located 40mm below the ball valve. |
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Where should the cold distribution be fitted on a cold water storage cistern? |
Side of cistern 40mm above the bottom. |
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Where should the feed to the cylinder be fitted on a cold water storage cylinder? |
Cylinder feed located 25 mm above distribution pipes to prevent scalding. |
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What size should an overflow pipe be? |
One size larger than cistern supply pipe. |
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Why is ball valve 40mm above the overflow? |
To ensure ball valve never becomes submerged. |
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What is purpose of ball valve back plate? |
To protect cistern wall from fatigue caused by continuous movement of ball valve. |
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How should two or more cisterns be connected? |
Must have mains water inlet to prevent top layer becoming stagnant. Each cistern have an overflow and opposite side exit on each cistern. |
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How is stagnation prevented on a single cold water storage cistern? |
Cisterns should not be oversized, distribution and feed pipe work should always be connected to opposite end to the mains inlet to allow water move across cistern. |
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What is a warning pipe? |
Is pipe half or three quarter inch in size runner to a position to warn the householder of an impending overflow. |
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What is domestic cisterns overflow? |
Is both overflow and warning pipe combined. |
