Worksheets150589 Central Heating Systems – Worksheet MCQs (Grade 14)
Total questions: 73
Worksheet time: 37mins
The primary purpose of domestic central heating is to?
Provide thermal comfort by balancing physical and personal factors
Maintain constant humidity only
Increase air velocity in rooms
Dry out building fabric
Which pair correctly lists one physical and one personal factor in thermal comfort?
Humidity & clothing
Air velocity & stress unrelated
Metabolism & open vent
Condensation & dew point
‘Full central heating’ is best defined as?
Simultaneous heating of all spaces to specified temperatures based on calculated heat losses
Heating some spaces below recommended temperatures
Heating only the living areas
Background heating to reduce condensation only
Which statement about one-pipe vs two-pipe systems is true?
Two-pipe systems deliver similar temperatures to all radiators via separate flow/return
One-pipe systems are more efficient and modern
Two-pipe systems rely on gravity only
One-pipe systems eliminate temperature drop across radiators
Before first fill, which check is essential?
All open ends capped/valves isolated and drain valves closed
Pump set to speed 3
TRVs removed
Cylinder thermostat set to 60°C
In open-vented systems, provisional fill level should be set in:
The feed & expansion cistern
The cold water storage cistern
The expansion vessel
The boiler heat exchanger
On sealed systems, initial filling should be done to about?
1 bar cold pressure
3 bar cold pressure
0.2 bar cold pressure
2.5 bar cold pressure
During staged filling of sealed systems, you should?
Turn off the filling loop between venting stages to prevent rapid overfilling
Leave the filling loop open until all radiators are vented
Fill via the F&E cistern
Open PRV continuously
BS EN 14336 requires heating systems be pressure tested to:
At least 30% above working pressure for a minimum of 2 hours
Exactly working pressure for 30 minutes
Twice working pressure for 10 minutes
1 bar for 1 hour
Prior to hydraulic testing you should:
Remove vulnerable items like the pump and ensure vents at high points are closed
Open PRV to atmosphere
Disconnect cylinder coil
Fill with glycol
If inspection reveals incorrectly positioned pump/vent connections, you should:
Rectify layout before commissioning proceeds
Proceed if no leaks
Increase pump speed
Add inhibitor and continue
Defective motorised valve supplied by manufacturer. First action?
Contact supplier/manufacturer for replacement per instructions
Attempt internal electrical repair
Bypass the valve permanently
Leave as is if heating works
Wet central heating primarily heats spaces by:
Circulation of heated water transferring heat via conduction, convection and radiation
Direct electric resistance only
Natural ventilation
Solar gain alone
Which list correctly names common wet system categories?
One-pipe low pressure; Two-pipe low pressure; Fully pumped; Sealed systems; Underfloor
Two-pipe only; Combi only; Solar only
Microbore only
Open flue only
Magnetic filters primarily remove:
Ferrous magnetite sludge from radiators and pipework
Copper oxide only
Limescale only
Air from system
To minimise corrosion from dissimilar metals you should:
Flush residues, add inhibitors/scale preventers, and fit magnetic filter
Use steel pipes only
Raise boiler flow temperature
Remove all TRVs
A Y-Plan system uses:
A 3-port mid-position valve to split flow between heating and hot water
Two 2-port zone valves
A 3-port diverter valve with priority
Gravity circulation only
In an S-Plan Plus, zoning typically includes:
Upstairs and downstairs heating circuits plus hot water, each separately controlled
Heating only
On open-vented systems, the memory aid for correct order is:
VCP – Vent, Cold feed, Pump
PVC – Pump, Vent, Cold feed
CPV – Cold feed, Pump, Vent
PCV – Pump, Cold feed, Vent
For sealed systems, the expansion vessel is usually placed on:
Return pipe on pump suction side
Flow pipe after pump
On the open vent
On the hot water draw-off
Microbore systems typically use branch pipe sizes of:
8mm or 10mm to radiators via manifolds
15mm only
28mm throughout
3/8" imperial exclusively
Maximum recommended loop length in microbore is approx:
15m combined (7.5m flow + 7.5m return)
30m combined
5m combined
Unlimited length
Solid fuel systems must include:
A heat leak radiator and be open-vented (no sealed components)
A sealed expansion vessel
Pressurised filling loop left connected
No thermostats
Which safeguarding control is typical on solid fuel?
Pipe stat set ~90°C to energise pump to dissipate excess heat
TRV with night setback
Weather compensation only
Open flue damper locked open permanently
Most domestic oil boilers use which burner type?
Pressure jet (atomising) burner
Vaporising only
Atmospheric gas burner
Pellet stirrer
Vaporising burners are commonly found on:
Older oil-fired cookers (Aga) gravity-fed
Modern condensing boilers
System boilers
Combi boilers
Condensing boilers achieve high efficiency by:
Cooling flue gases below dew point to recover latent heat
Using pilot lights
Increasing gas pressure
Bypassing the heat exchanger
Combination boilers provide:
Instantaneous hot water with heating diverted via a diverter valve (hot water priority)
Stored hot water via cylinder
Gravity hot water only
No hot water
Modern panel radiators emit roughly:
~70% convection, ~30% radiation
100% radiation
100% convection
50/50
A typical radiator installation height from finished floor to radiator underside:
150mm
50mm
300mm
Flush to floor
TRVs control:
Room temperature by modulating water flow at each radiator
Boiler firing rate directly
System pressure
Flue gas temperature
Automatic bypass valves open when:
Flow is restricted as TRVs/zone valves close
Pump stops
Cylinder stat calls
Room stat is satisfied
Which set correctly lists core information sources?
Water Regulations, Building Regs (L1A/B, J), BS standards, manufacturer instructions
Social media guides
Installer forums only
Historic codes only
When manufacturer instructions conflict with older codes of practice:
Follow manufacturer instructions
Ignore them
Follow forum advice
Use personal preference
Preparatory building work includes:
Marking routes, cutting notches/holes, fixing supports, protecting areas
Fitting TRVs first
Filling system
Setting cylinder stat
Site prep aims to:
Enable safe, efficient installation with minimal fabric damage
Speed only
Reduce materials cost only
Avoid insulation
Protection measures during work include:
Dust sheets, isolations, careful removal, reinstatement, property protection
Remove doors
Disable alarms
Open all windows
On completion you should:
Make good and clean areas; reinstate components; ensure safe operation
Leave debris
Over-pressurise system
Disable thermostats
Common pipe materials include:
Copper, low carbon steel, approved plastics (PB/PEX)
Lead only
Cast iron only
PVC waste pipe
Older imperial copper sizes require:
Adapter fittings when joining to modern metric sizes
No adaptation
Crimping only
Threading only
Typical tools for CH work include:
Pipe cutters, benders, threading sets, drills, spanners, radiator keys
Paint rollers
Garden tools
Laser cutters only
Power tool safety includes:
Use PPE and correct bits; isolate supplies as needed
No goggles needed
Remove guards
Wet-hand operation
Dressing a radiator includes:
Fitting valve tails, air vent, blanking plug before hanging
Connecting to pipework first
Filling system
Setting TRV to max
Recommended underside-to-floor clearance:
~150mm
~50mm
Flush
~300mm
Pipework in roof spaces should be:
Insulated to Water Regulations to guard against freezing
Left bare
Heated by trace only
Plastic only
At cylinders, pipes including vent should be insulated for:
1m beyond connection or until concealed
0.2m
No insulation required
5m
Positioning/fixing of pipework must consider:
Suspended floors, solid floors, walls, frost-prone areas, heat exposure
Radiator colour
Furniture style
Window type only
Secure pipework by:
Adequate clips/brackets at recommended spacings
Minimal fixings
Cable ties only
Glue
Thermal expansion is catered for by:
Expansion loops/sliding supports
Fixed rigid runs only
Over-tight brackets
Smaller pipe sizes
In plastics pipework, you must:
Allow for creep/expansion per guidance
Overheat runs
Avoid support
Use lead bends
Clip spacing depends on:
Pipe size/material and orientation
Radiator height only
Boiler type only
Colour of clips
Brackets should be selected to:
Prevent movement/noise; maintain neatness
Match décor only
Allow sagging
Be oversized always
Selecting joints depends on:
Material, pressure, temperature, accessibility
Paint colour
Flue type
Room size
Lead connections to new pipework should use:
Acceptable conversion methods per standards
Direct solder
Glue
Push-fit only
In open-vented systems, the pump should be on:
Flow with vent/cold feed on suction side creating neutral point
Return always
Across bypass
Room thermostats should be sited:
In a freely-aired heated room on internal wall ~1.2m high
Above radiator
In unheated porch
Behind curtains
Boiler connections typically require:
Minimum 1m copper before changes; use manufacturer compression sets
Immediate plastic transitions
Threaded steel only
No unions
Radiator valve tails should be sealed with:
PTFE/jointing compound and tightened with radiator spanner
Insulation tape
No sealant
Silicone
Positioning/fixing new pipework must ensure:
Accessibility for service and follow orientation guidance
Hidden components
Random routing
Unsupported spans
Sealed system PRV discharge should terminate via:
A tundish to a safe location outside
Surface water drain
Loft tray
Open gutter
Connecting to old imperial copper often needs:
Metric-imperial converter fittings
Direct crimp
Friction fit
Brazing only
Old microbore 3/8" pipe requires:
Replacement as adapters discontinued
Direct insert to 10mm
Compression with 15mm olive
Threaded union only
Maintenance scheduling relies on:
Manufacturer instructions and job schedules
Forum advice
Customer preference
Weather forecasts
Using instructions ensures:
Compliance, safety and warranty retention
Longer paperwork
Lower temperature
Shorter pipe runs
Routine checks include:
Valves free, venting, pump direction, corrosion signs, filter cleaning
Colour matching
TRV removal
Leaving filling loop open
Water sample with black magnetite suggests:
Electrolytic corrosion of ferrous components
Air ingress only
Aluminium corrosion only
No issue
Leakage repair sequence begins with:
Isolate power/water, drain system, then repair
Open PRV and continue heating
Increase pump speed
Add inhibitor only
Electrical control valve replacement should be done by:
Qualified, experienced operative
Anyone
Customer
Trainee unsupervised
A maintenance record should include:
Engineer name, dates, system type, boiler details, emitters, service dates, faults, actions, materials
Only boiler serial
Only temperatures
Nothing
Recording corrosion observations helps to:
Track issues for future corrective actions
Increase pressure
Reduce paperwork
Avoid cleaning
To minimise downtime you should:
Prepare work so final connections last; inform customer of off-time
Drain immediately without plan
Work across entire house
Avoid notices
Customer communication before isolation should:
Explain scope, areas affected, duration
Be avoided
Be technical only
Promise zero impact
Before decommissioning you must provide:
Information on areas affected, timing, isolation steps, safety notes
Invoice only
Marketing
Warranty card
