NEW
Font size
WorksheetsCentral Heating 2
Total questions: 42
Worksheet time: 21mins
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.
What is the primary function of the open safety vent pipe?
The primary function of the open vent pipe is to allow for expansion and contraction of the heated system water. It also allows the system to operate at atmospheric pressure.
The primary function of the open vent pipe is to provide a safety outlet should the system overheat. It also allows the system to operate at atmospheric pressure.
Allows water to feed the boiler.
Allows the boiler to fill the system.
What is the minimum size of the OSV and why does it have to be positioned a minimum of 450mm above the water level of the F&E cistern?
The vent needs to be a minimum of
450mm above the water level to
prevent the sucking effect of the pump.
The minimum pipe size is 15mm.
The vent needs to be a minimum of
450mm above the water level to
prevent the surge effect of the pump.
The minimum pipe size is 22mm.
The vent needs to be a minimum of
450mm above the water level to
prevent the push effect of the pump.
The minimum pipe size is 28mm.
The vent needs to be a minimum of
400mm above the water level to
prevent the surge effect of the pump.
The minimum pipe size is 22mm.
If the cold feed , open safety vent pipe and circulating pump are positioned incorrectly on an open vented central heating system; what problems could this cause?
The system will not work properly and may even induce system corrosion due to constant aeration of the system water.
It doesn't matter as the positions of these items are not important and will not affect system longevity and operation.
The system will be noisy.
Just fit a combination boiler.
On an open vented, fully pumped central heating system, where should the open safety vent and cold feed be positioned?
The open vent and the cold feed should be positioned on the boiler primary flow, before the circulator (negative/suction side) with a maximum of 150mm between them.
The open vent and the cold feed should be positioned on the boiler primary flow, after the circulator (positive/ push side) with a maximum of 250mm between them.
The open vent and the cold feed should be positioned on the boiler primary flow, before the circulator (suction side) with a minimum of 150mm between them.
The open vent and the cold feed should be positioned on the boiler primary return, after the circulator (suction side) with a maximum of 150mm between them.
Why are the open safety vent and cold feed pipe positioned on the boiler primary flow on the suction side of the circulating pump?
Basically this positioning allows the circulating pump to act on both pipes with equal suction preventing air being drawn into the system.
Basically this positioning allows the circulating pump to act on both pipes with unequal suction preventing air being drawn into the system.
Allows extra water to be drawn down the cold feed pipe to fill the system.
Prevents the cold feed pipe from blocking up.
What is an air separator?
The air separator is basically an undersized pipe with a cold feed and vent pipe connections. The water swirls around, separating the air.
The air separator is basically an oversized pipe with a cold feed and vent pipe connections. The water swirls around, separating the air.
The air separator is basically an oversized pipe with a cold feed and vent pipe connections. The water swirls around, separating the debris.
The air separator is basically an oversized pipe with a cold feed and vent pipe connections. The water swirls around, separating the air and debris .
Where is the neutral point of the system?
Where the open safety vent connects to the system.
Where the cold feed connects to the system.
Where the circulating pump is connected into the system.
When the boiler is fitted at the same level as the cold feed.
Where should the circulator be fitted in relation to the cold feed and vent pipe?
On the boiler primary return before the cold feed and vent pipe.
On the boiler primary flow after the open safety vent and cold feed pipe.
On the central heating primary flow after the open safety vent and cold feed pipe.
On the Central heating primary flow , before the hot water primary flow connection with the open safety vent on the suction side and the cold feed after the circulator.
What is the 'golden rule' regarding the positioning of the circulating pump and cold feed?
The golden rule is that the circulator must always draw on the open safety vent and pressurise the cold feed.
The golden rule is that the circulator must never draw on the cold feed but always on the open safety vent.
The golden rule is that the circulator must never draw on the cold feed.
The golden rule is that the circulator must always draw on the cold feed.
If the radiators are not heating up and the hot water is only lukewarm, what could be a possible fault?
Immersion element thermostat incorrectly set.
Boiler thermostat set too high.
It could be due to a sluggish or poor performing pump that requires replacement.
No water in the system.
What causes aeration of the system water?
Constant movement of the water at the F&E cistern will aerate the water causing system corrosion.
Not flushing the system properly after installation.
Ferrous metals in the system.
Non ferrous metals in the system.
What is a two port motorised valve commonly known as?
Commonly known as a mid position valve, this can be
activated by a room or cylinder thermostat.
Commonly known as a zone valve, this can be
activated by a room or cylinder thermostat.
Commonly known as a diverter valve, this can be
activated by a room or cylinder thermostat.
Commonly known as a snifter valve, this can be
activated by a room or cylinder thermostat.
On a mid position valve, what does port A connect to?
The boiler primary flow
The hot water primary flow
The central heating primary flow
All of the above
Why is it important to position the circulator correctly to ensure that the system is under positive pressure?
To prevent the ingress of air into the system, causing corrosion.
To prevent system noise.
To allow the boiler to operate at a higher temperature.
To prevent the system leaking.
How far up a hot water storage cylinder is the cylinder thermostat situated?
One third from the bottom.
One third from the top.
In the middle third.
Fixed to the hot water draw off.
Name the three types of hot water cylinder thermostat?
Electric, mechanical and solar.
Bi-metallic strip, volatile liquid or gas type.
Bi-metallic strip, volatile water or electric type.
Bi-metallic strip, volatile liquid or solar type.
How far up the wall should a room thermostat be fitted?
2 metres.
1 metre.
1.5 metres.
2.5 metres.
Where is the boiler thermostat located?
On the wall next to the boiler.
In the living room.
In the boiler.
In the airing cupboard, attached to the hot water primary flow.
What regulation and guide requires the fitment of thermostatic radiator valves on the system?
Building Regulations part J and the Heating Compliance Guide require TRVs to be fitted on systems.
Building Regulations part G and the Heating Compliance Guide require TRVs to be fitted on systems.
Building Regulations part F and the Heating Compliance Guide require TRVs to be fitted on systems.
Building Regulations part L and the Heating Compliance Guide require TRVs to be fitted on systems.
What is a central heating programmer?
These allow independent timed control of both the hot water and the central heating.
These allow fixed timed control of both the hot water and the central heating.
These allow independent timed control of the hot water but not the central heating.
These allow priority control of the hot water and timed control of the central heating.
What are frost thermostats and pipe thermostats for?
These are incorporated into a system to stop vulnerable parts of the system from overheating.
These are incorporated into a system to stop vulnerable parts of the system from freezing.
Give independent temperature control of the loft , garage and outhouse.
Make the system heat up faster in the winter.
What is a magnetic system cleaner?
Essentially, they contain an electro-magnet that collects all the corroded brass particles – stalactites. The magnet is removed when the system is serviced, flushing the stalactites away and keeping the system water in good condition.
Essentially, they contain a magnet that collects all the corroded copper and aluminium particles – The magnet is removed when the system is serviced, flushing the particles away and keeping the system water in good condition.
Essentially, they contain a magnet that collects all the corroded iron particles – magnetite. The magnet is removed when the system is serviced, flushing the magnetite away and keeping the system water in good condition.
They stop the boiler from becoming overheated.
What is an inhibitor?
A chemical protection against scale and corrosion within a central heating system.
A magnetic filter protection against scale and corrosion within a central heating system.
A base ion exchange protection against scale and corrosion within a central heating system.
A sacrificial anode protection against scale and corrosion within a central heating system.
What is a lock sheild valve?
To allow the radiator to be isolated and removed for decorating.
The lock shield valve is for the engineer to use so the system can be balanced.
To slow down the velocity of the water through the radiator to prevent system noise.
As a secondary means of control.
Why should the system be balanced?
To ensure that the boiler has enough flow of water through its heat exchanger.
To ensure the flow of water through the hot water primary coil is not to fast, causing noise.
To ensure that the pump speed is not exceeded.
To ensure that all the radiators heat evenly and at the same time.
What is the index radiator?
This is the radiator that heats up last and therefore has the greatest resistance.
This is the radiator that heats up first and therefore has the greatest resistance.
This is the radiator that heats up last and therefore has the least resistance.
This is the radiator that heats up first and therefore has the least resistance.
What tool do we use to fit the radiator valve tails to the radiators?
A radiator bleed key
A radiator valve key
An adjustable spanner
Stillsons wrench
What is an automatic bypass valve?
Allows a set flow of water through the cylinder coil.
This allows the flow of water through the boiler if the TRVs and zone valves close.
This allows the flow of water through the boiler if the TRVs and zone valves open.
This allows the flow of water through the boiler if the TRVs open and zone valves close.
What is a filling loop?
A fixed, permanent connection between the incoming mains and the central heating system. It is used on pressurised sealed systems, including combination boilers.
A fixed, permanent connection between the cold feed and the central heating system. It is used on pressurised sealed systems, including combination boilers.
A flexible, temporary connection between the incoming mains and the central heating system. It is used on pressurised sealed systems, including combination boilers.
A flexible, temporary connection between the cold feed and the central heating system. It is used on pressurised sealed systems, including combination boilers.
What is an expansion vessel?
These are used on a sealed system to take up the 4% expansion of the heated water and are sized according to the system. Inside the vessel is a rubber diaphragm or bladder. On the dry side it is charged through a schrader valve to 1bar pressure. On the wet side the expanded water pushes against the diaphragm, compressing the air but containing the expansion.
These are used on an open vented system to take up the 4% expansion of the heated water and are sized according to the system. Inside the vessel is a rubber diaphragm or bladder. On the dry side it is charged through a schrader valve to 1bar pressure. On the wet side the expanded water pushes against the diaphragm, compressing the air but containing the expansion.
These are used on an open vented hot water cylinder to take up the 4% expansion of the heated water and are sized according to the system. Inside the vessel is a rubber diaphragm or bladder. On the dry side it is charged through a schrader valve to 1bar pressure. On the wet side the expanded water pushes against the diaphragm, compressing the air but containing the expansion.
Acts as a reservoir of system water for the boiler.
What is this component?
A pressure relief valve.
An automatic bypass valve.
A temperature/pressure relief valve
A lock sheild valve.
What is this component and what is it used for?
Fitted at high points in the system, these are commonly found fitted inside boilers. They allow air to be released from the system, closing automatically.
Fitted at low points in the system, these are commonly found fitted outside boilers. They allow air to be released from the system, closing automatically.
Fitted at high points in the loft, these are commonly found fitted to hot water cylinders. They allow air to be released from the system, closing automatically.
Fitted at high points in the system, these are commonly found fitted inside boilers. They allow water to be released from the system, closing automatically.
