Central Heating 2

Where is the feed and expansion cistern commonly located?

• In the basement

• In the loft

• In the airing cupboard

• On top of the boiler

What is the main purpose of the feed and expansion cistern?

• To ensure that the boiler has a constant supply of cold water.

• To allow for overheated water to escape from the open safety vent safely.

• To allow the heated water

  in the system to expand and to operate at atmospheric pressure.

• To allow for a head of water above the circulating pump.

Where and how should the feed and expansion cistern be sited?

• The base of the F&E should be at the same level as the cold water storage cistern and be fully supported over its base.

• The base of the F&E should be at a higher level than the cold water storage cistern to prevent crossflow and back siphonage.

• It should be mounted on two brackets holding it to the party wall.

• Its self supporting and should be lower than the cold water storage cistern to allow for ease of servicing.

What is the most common size or capacity of a feed and expansion cistern and material it is made from?

• The F&E is commonly an 18-litre galvanised steel cistern.

• The F&E is commonly an 20-litre asbestos cement cistern

• The F&E is commonly a 5 gallon grey fibre glass cistern.

• The F&E is commonly an 18-litre, black plastic cistern.

What is the minimum diameter of the cold feed pipe from a F&E cistern and where is it normally positioned?

• The 15 mm cold feed is located to the side of the F&E and should not have any valves.

• The 12 mm cold feed is located to the side of the F&E and should not have any valves.

• The 18 mm cold feed is located to the side of the F&E and should have an isolation valve.

• The 15 mm cold feed is located to the side of the F&E and should have an isolation valve.

What is the minimum diameter of the open safety vent pipe, where should it be located and what is its minimum height above the water level of the F&E cistern?

• The 15mm open vent from the primaries is located over the top of the F&E and must rise a minimum of 450mm above the water level. It should not have any valves.

• The 22mm open vent from the primaries is located over the top of the F&E and must rise a minimum of 450mm above the water level. It should have an isolation valve for servicing.

• The 22mm open vent from the primaries is located over the top of the F&E and must rise a minimum of 450mm above the water level. It should not have any valves.

• The 28mm open vent from the primaries is located over the top of the F&E and must rise a minimum of 450mm above the water level. It should not have any valves.

What is the minimum distance a F&E cistern must be positioned above the circulator?

• The F&E should be located a minimum of 0.5 of a metre above the circulator.

• The F&E should be located a minimum of 1 metre above the circulator.

• The F&E should be located a minimum of 10 metres above the circulator.

• The F&E should be located a maximum of 1 metre above the circulator.

How is the F&E cistern supplied and what type of water level control valve be fitted?

• The cold water down service supplies the BS 1010 valve installed in the F&E. Prior to the valve there must be a service valve installed to allow for maintenance.

• The rising main supplies the BS 1212 Part 3 FOV installed in the F&E. Prior to the FOV there must be a service valve installed to allow for maintenance.

• The rising main supplies the BS 1212 Part 1 FOV installed in the F&E. Prior to the FOV there must be a service valve installed to allow for maintenance.

• The rising main supplies the BS 1212 Part 2 FOV installed in the F&E. Prior to the FOV there must be a service valve installed to allow for maintenance.

What is the typical cold water level depth the FOV is set to in a F&E cistern? Why is this?

• The water level set by the FOV in the cistern should be at a low level, 100 mm normally, just covering the cold feed exit. This will allow for plenty of expansion.

• The water level set by the FOV in the cistern should be at 25mm to 50mm below the overflow outlet level, covering the cold feed exit. This will allow for plenty of expansion.

• The water level set by the FOV in the cistern should be at a low level, 300 mm normally, just covering the cold feed exit. This will allow for plenty of expansion.

• The water level set by the FOV in the cistern should be at a high level, covering the cold feed exit. This will allow for plenty of expansion.

How much extra water will have to be taken up by the F&E cistern when the system water is heated?

• The system water will expand by 1600 times its original volume

  when heated, and this expansion needs

  to be taken up in the F&E.

• The system water will expand by 10%

  when heated, and this expansion needs

  to be taken up in the F&E.

• The system water will expand by 4%

  when heated, and this expansion needs

  to be taken up in the F&E.

• The system water will expand by 4%

  when heated, and this expansion needs

  to be taken up in the cold water storage cistern.