Domestic Appliances

What is a gas boiler?

• AAn appliance that burns gas to heat water for space heating and/or domestic use✓
• BA meter that records how much gas is consumed
• CAn appliance that stores gas under pressure so it can be used later by the heating system
• DAn appliance that burns gas to heat air, which is blown through ducts

Answer: Gas boilers burn natural gas to provide heating and hot water.

What is a regular (traditional) boiler?

• AAny boiler at all, since the term is used quite loosely by the manufacturers
• BA boiler requiring a separate hot water storage cylinder and feed tank✓
• CSame as combi
• DSealed system

Answer: Regular boilers work with separate hot water cylinders and feed tanks.

What is a gas fire?

• AA decorative or functional gas-burning appliance producing heat and flame✓
• BA complete heating system that serves the radiators throughout the property
• CA rarely fitted appliance
• DJust decoration

Answer: Gas fires provide both decorative flame effect and heat output.

What is a gas cooker?

• AAn electrical appliance rather than a gas one
• BJust a stove
• CHeating only
• DA kitchen appliance with gas hob and/or oven for cooking✓

Answer: Gas cookers use gas for burners and ovens in kitchens.

What is a gas water heater (instantaneous)?

• AAn appliance type that is no longer made
• BJust a circulator
• CAn appliance that heats water on demand without storage✓
• DA storage tank

Answer: Instantaneous heaters provide hot water on demand without a storage tank.

What should be checked on a gas cooker during servicing?

• ABurner flame colour, gas tightness, stability, and seals✓
• BCookers fall outside the scope of a gas check and are not checked regularly
• CJust the cleanliness of the hob and the inside of the oven cavity
• DOnly the oven burner, as the hob burners are visible to the user anyway

Answer: Cooker servicing checks burner operation, gas connections, and seals.

What is a pilot light on a gas appliance?

• AMain burner
• BA small flame that ignites the main burner when needed✓
• CAlways on
• DA small indicator lamp on the front panel showing the appliance is safe

Answer: Pilot lights are small flames that ignite main burners when called for.

What is ignition in a gas appliance?

• AThe burner itself, where the gas and air mix before they are lit
• BThe method used to light the gas (pilot, electronic, piezo)✓
• CUnimportant, as all modern appliances light themselves reliably
• DJust the temperature that the flue gases reach when the burner lights

Answer: Ignition systems can be pilot lights, electric spark, or piezoelectric.

What is a gas fire with balanced flue?

• ARegular open-flue fire
• BAny fire
• CA sealed fire with outside air intake and flue exhaust ducts✓
• DA type that is no longer available to install

Answer: Balanced-flue gas fires don't require room ventilation.

What is a gas water heater storage (tank) type?

• ARare in the UK, since all water heaters are now instantaneous
• BAn instantaneous heater that raises the water temperature as it flows
• CAn appliance storing heated water in a tank for later use✓
• DA combination boiler that provides both heating and hot water

Answer: Storage-type heaters maintain a tank of hot water for continuous supply.

What is the purpose of a thermostat on a gas water heater?

• AControls the heating temperature and prevents overheating✓
• BIt is fitted only as a safety device and plays no part in normal running
• CUnnecessary, because the burner runs at a fixed rate at all times
• DIt simply gives the user a temperature display on the front of the heater

Answer: Thermostats maintain desired water temperature and prevent scalding.

What should be checked on a gas fire during inspection?

• AFlame safety device, flue, seals, and proper operation✓
• BThe appearance of the fire front only
• CLeft unchecked
• DOnly colour

Answer: Fire inspections verify flame control, flue operation, and safety devices.

How are the combustion products of a domestic gas cooker removed?

• AIt is flueless, so they enter the room, which must be ventilated✓
• BThrough a balanced flue to outside, like a room-sealed boiler
• CThrough an open flue connected to a chimney
• DThrough a fan-assisted flue built into the cooker hood

Answer: A domestic gas cooker is a flueless appliance. Its combustion products go into the room, so the room needs the ventilation set out in BS 5440-2 and the maker's instructions. A cooker hood is not a flue.

What is a room-sealed cooker?

• AA sealed cooker drawing outside air and venting outside without room air✓
• BAn open-flue cooker that takes its combustion air from the kitchen itself
• CA cooker connected by a flexible hose rather than rigid pipe
• DAny sealed appliance, whether or not it takes its air from outside the room

Answer: Room-sealed cookers are independent of room air and ventilation.

What is a consumer unit (fuse box) requirement for gas appliances?

• AQuite irrelevant, because a gas appliance never needs an electrical supply of any kind at all
• BOnly relevant for heating appliances, and never for cookers, gas fires or water heaters
• CAdequate electrical capacity for any electric components (boiler controls, pumps, fans)✓
• DA dedicated circuit for every gas appliance in the property

Answer: Gas appliances with electrical components need proper electrical supply and protection.

What is condensation in a condensing appliance?

• AJust the moisture that forms on the outside of the appliance casing in cold weather
• BSomething that only happens in winter, when the outside air temperature is coldest
• CA side effect of no consequence, since the water produced simply evaporates in the flue
• DThe cooling of flue gases below dew point, releasing latent heat and water✓

Answer: A condensing appliance cools its flue gases below their dew point, so water vapour condenses and gives up its latent heat. This raises efficiency and produces acidic condensate that must be drained away.

What is the efficiency advantage of a condensing boiler?

• ACaptures latent heat from condensation, achieving 90%+ efficiency vs. 80% for traditional boilers✓
• BIt is only more efficient during the summer months, when the demand for heating is at its very lowest
• CIt heats water faster, though it uses the same amount of gas
• DJust a marketing claim, since the efficiency is really the same as that of an older non-condensing boiler

Answer: Condensing boilers reclaim waste heat, significantly reducing gas consumption.

What must be done with condensate from a condensing appliance?

• AAllow it to evaporate away inside the casing of the appliance
• BDischarge it down the face of the external wall below the flue terminal
• CSafely drain it through a siphon trap to waste or soil drain✓
• DIgnore it, since the quantity produced over a season is very small

Answer: Condensate must be properly drained through a trap to prevent freezing and odours.

What is a gas supply isolation for an appliance?

• AJust the valve at the meter, which isolates the whole of the property at once
• BRedundant, because the appliance itself already has an on/off control fitted
• COptional, and fitted only when the customer specifically asks for one to be provided
• DAn isolation valve immediately before the appliance for safe disconnection✓

Answer: Each appliance should have an isolation valve for safe disconnection.

What is the safe maximum hot water temperature at the tap to prevent scalding, especially for vulnerable users?

• A65°C, the same as the temperature at which water is stored in the cylinder
• B100°C, since water leaves the tap at a lower temperature than it is stored
• CAround 44-50°C, thermostatically controlled (e.g. via a TMV)✓
• DA working thermostat on the boiler removes the need for any limit at the tap

Answer: Hot water should be STORED at 60°C or above to control Legionella bacteria, but that storage temperature would scald someone at the tap. A thermostatic mixing valve (TMV) blends in cold water so the water actually delivered is much cooler — around 44-50°C, lower still for vulnerable users — while the cylinder itself stays hot enough to control Legionella.

What is a timer or time switch on gas appliances?

• AA safety cut-out that stops the burner if it overheats
• BA convenience feature only, which makes no difference to the fuel used
• CPurely optional equipment that has no effect on how the appliance runs
• DA device controlling when appliances operate for energy efficiency✓

Answer: Timers control appliance operation for efficiency and comfort.

What is a boiler reset function?

• AA control that returns the settings to the factory defaults
• BA feature that allows the boiler to restart by itself as soon as the fault has cleared
• CA safety feature that stops boiler operation after a fault and requires manual reset✓
• DJust switching the power off and then back on again at the fused spur beside the boiler

Answer: Reset functions prevent automatic restart after faults, requiring manual investigation.

What should be documented for appliance servicing?

• AOnly the engineer's registration number
• BOnly the repairs carried out, since the tests are routine
• CAppliance details, tests performed, findings, any faults, and remedial actions✓
• DThe content is left entirely to the engineer

Answer: Service records document work done, findings, and recommendations.

What is the role of a programmer in heating control?

• AOnly the control of room temperature, which it does through a wall sensor
• BIt has no function
• CJust display
• DA device controlling when heating and hot water operate on a schedule✓

Answer: Programmers schedule heating and hot water operation for comfort and efficiency.

What is a smart thermostat?

• AA device that measures the room temperature and nothing more
• BAn intelligent device learning usage patterns and optimising heating for efficiency✓
• COnly for modern homes
• DJust a display

Answer: Smart thermostats learn patterns and optimise heating schedules automatically.