Heating Systems Vocabulary

Vocabulary flashcards covering open-vented, sealed, S-plan, and Y-plan heating systems based on current Approved Documents G and L.

Approved Documents G and L

Current regulatory guidance documents on which heating system standards and requirements are based.

Open-Vented Heating System

A heating system open to the atmosphere through a feed and expansion cistern, operating under static low pressure created by the height of the water.

Feed and Expansion Cistern

A tank normally located in the loft or highest suitable point of an open-vented system that replenishes lost water and accommodates thermal expansion.

Open Vent Pipe

A pipe in an open-vented system that provides a safety path for thermal expansion and prevents excessive pressure.

Sealed Heating System

A closed heating system with no open connection to the atmosphere, benefiting from reduced air exposure to lower corrosion risk.

Expansion Vessel

A sealed-system component containing water on one side and pressurised gas on the other, designed to absorb the increased volume of heated water.

Pressure Relief Valve (PRV)

A protective valve in a sealed heating system that discharges water if the internal pressure becomes excessively high.

Pressure Gauge

A device that displays the operational pressure within a heating system.

Filling Loop

A connection used to fill or repressurise a sealed heating system.

S-Plan System

A fully pumped heating system that uses separate motorised valves to allow central heating and domestic hot water to operate independently.

2-Port Motorised Valve

A type of valve commonly used in S-plan systems, typically configured with two valves controlled by room and cylinder thermostats.

Y-Plan System

A fully pumped heating system that uses a single 3-port motorised valve to direct water flow between heating and hot water.