Unvented Hot Cylinder Worksheet

Front

How does an Unvented Hot Cylinder work?

Back

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.

Front

How much does water expand by when heated?

Back

4%

Front

What are all your components on an unvented cylinder?

Back

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.

Front

What does a pressure reducing valve do?

Back

Reduces mains pressure going into the cylinder

Front

Minimum and Maximum for D1 & d2 pipework?

Back

600mm and 300mm

Front

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

Back

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

Front

What temperatures do the tiers of safety blow off at?

Back

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

Front

What does the Temperature and pressure relief do?

Back

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.

Front

What components are in a combination valve?

Back

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

Front

Why do you have a tundish?

Back

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.