Unvented Hot Cylinder Worksheet

How does an Unvented Hot Cylinder work?

• Unvented water cylinders work by drawing water directly from the mains and heating it within a sealed, high-pressure cylinder, eliminating the need for a cold water storage tank. This design allows for a stronger, more consistent hot water flow at mains pressure.

• Unvented water cylinders work by using gravity from a rooftop tank to supply water at low pressure, which is then heated by solar panels only.

• Unvented water cylinders require a separate boiler to pump water into an open vented tank before heating, resulting in variable water pressure.

• Unvented water cylinders operate by storing cold water in an attic tank and heating it with an immersion heater, providing hot water at low pressure.

How much does water expand by when heated?

• 4%

• 1%

• 10%

• 0.5%

What are all your components on an unvented cylinder? You need to name them.

• Cylinder, Immersion Heater, Pressure and Temperature Relief Valve, Pressure Reducing Valve (PRV), Expansion Vessel, Balanced Cold Water Outlet, Cold Water Inlet, Secondary Return Connection (Optional), Tundish, Combination Valve, Thermostat.

• Cylinder, Radiator, Gas Valve, Expansion Tank, Hot Water Tap, Cold Water Storage Tank, Drain Valve, Air Vent, Pump, Flow Switch, Timer.

• Cylinder, Immersion Heater, Pressure Reducing Valve, Radiator, Gas Burner, Expansion Tank, Cold Water Storage Tank, Flow Switch, Timer, Air Vent, Pump.

• Cylinder, Immersion Heater, Pressure and Temperature Relief Valve, Pressure Reducing Valve (PRV), Expansion Vessel, Radiator, Gas Valve, Hot Water Tap, Drain Valve, Pump, Timer.

What does a pressure reducing valve do?

• Reduces mains pressure going into the cylinder

• Increases the temperature of the water

• Filters impurities from the water

• Stops water flow completely

What are the Minimum and Maximum for your D1 & d2 pipework?

• 600mm and 300mm

• 500mm and 200mm

• 700mm and 400mm

• 800mm and 100mm

What is the three tiers of safety for an unvented cylinder?

• control thermostat, a high-limit thermostat (ECO), and a temperature and pressure relief valve

• pressure gauge, expansion vessel, and drain valve

• immersion heater, cold water tank, and stopcock

• flow switch, pump, and check valve

What temperatures do the tiers of safety blow off at?

• control thermostat 60 - 65, a high-limit thermostat (ECO) 80 - 85, and a temperature and pressure relief valve 90 - 95

• control thermostat 40 - 45, a high-limit thermostat (ECO) 60 - 65, and a temperature and pressure relief valve 70 - 75

• control thermostat 70 - 75, a high-limit thermostat (ECO) 90 - 95, and a temperature and pressure relief valve 100 - 105

• control thermostat 50 - 55, a high-limit thermostat (ECO) 70 - 75, and a temperature and pressure relief valve 80 - 85

What does the Temperature and pressure relief do?

• It automatically releases water if the cylinder's temperature or pressure exceeds safe limits, preventing potential damage or hazards. Specifically, it discharges water if the temperature reaches 95°C.

• It increases the temperature and pressure inside the cylinder to improve efficiency.

• It prevents water from entering the cylinder under any circumstances.

• It only monitors the temperature but does not take any action if limits are exceeded.

What components are in a combination valve?

• a pressure reducing valve, a check valve, an expansion valve, and a line strainer

• a thermostat, a relay, a fuse, and a compressor

• a solenoid valve, a condenser, a receiver, and a filter drier

• a blower motor, a capacitor, a relay, and a thermostat

Why do you have a tundish?

• A tundish is a crucial safety component in an unvented hot water cylinder system. Its primary purpose is to act as a visual indicator of any water discharge from the pressure relief valve (PRV), alerting homeowners to potential issues like over-pressure or a malfunctioning valve. It also acts as an airgap.

• A tundish is used to increase the water pressure in the hot water cylinder system.

• A tundish is installed to filter impurities from the water supply before it enters the cylinder.

• A tundish is designed to regulate the temperature of the water in the cylinder automatically.