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What are the two categories of modern domestic central heating systems based on?

• Water source and pressure

• Water temperature and pressure

• Water filling method and pressure

• Water circulation method and pressure

What type of system is fed directly from the mains cold water and incorporates an expansion vessel?

• Two-pipe semi-gravity with heat sink system

• Low pressure, open vented systems

• Sealed, pressurised systems

• One-pipe semi-gravity system

Which type of system uses convection currents to circulate the water around the radiators?

• C plan plus semi-gravity system

• C plan semi-gravity

• One-pipe semi-gravity

• Two-pipe semi-gravity with heat sink

What is the drawback of the one pipe system?

• Each radiator progressively cools down

• All heat emitters reach the same temperature

• Limited heat control

• Boiler cycling

Which system has separate pipes for the flow and return, and water is forced into the heat emitters?

• Low pressure, open vented systems

• One pipe system

• Two-pipe

• C plan plus semi-gravity system

What is the control on the heating in the system with separate pipes for the flow and return?

• Room stat

• Pump switch

• Thermostat

• Boiler control

Which system has gravity circulation to the hot water circuit but pumped circulation to the heating circuit?

• One-pipe semi-gravity

• C plan plus semi-gravity system

• C plan semi-gravity

• Two-pipe semi-gravity

What is the main advantage of the two-pipe semi-gravity system?

• All heat emitters reach the same temperature

• Limited heat control

• Cheaper to run

• Boiler cycling

What is the main disadvantage of the two-pipe semi-gravity system?

• Limited heat control

• All heat emitters reach the same temperature

• Cheaper to run

• Boiler cycling

What type of system has no pump for either hot water or heating, resulting in lengthy heat-up time?

• C plan plus semi-gravity system

• C plan semi-gravity

• Two-pipe semi-gravity with heat sink

• One-pipe gravity