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Central Heating

Exam revision materials for Plumbing Level 2&3 and ACS Gas Safety test

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Pipework

Sealed Systems

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Maintenance

Commissioning

Heating system water analysis

Servicing

Controls

Circulating Pump

Heating System Controls

Minimum Requirements

Room Thermostats

Regulations

Regulations

Heat Emitters

Heat Loss Calculation

Radiator Sizing

Types

Pipework

Fully Pumped Hot Water and Central Heating

Gravity Hot Water and Pumped Central Heating

Gravity System

Open-vented System

Pipework Sizing

Pipework Systems

Sealed Systems

System Layout

Underfloor Heating

Boilers

Boiler Sizing

Flue Types

Gas Boilers

Heat Pumps

Oil Fired Boilers

SEDBUK Rating

Solid Fuel Boilers

Components

  • Expansion vessel
    • the capacity depends on:
      • initial charge pressure in the system
      • volume of water in the system
      • Safety valve release pressure
  • Filling loop (with check valves)
  • Pressure relief valve (usually set to release at 3 bar)
  • Pressure gauge
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Expansion Vessel

  • Use BS 5449 and Domestic Heating Design Guide
Safety Valve Setting 3.0 bar 2.5 bar 2.0 bar
Initial Vessel Charge (bar) 0.5 1.0 1.5 0.5 1.0 1.5 0.5 1.0
Total water content of system (Litres) Expansion vessel volume
25 2.1 2.7 3.9 2.3 3.3 5.9 2.8 5.0
50 4.2 5.4 7.8 4.7 6.7 11.8 5.6 10.0
75 6.3 8.2 11.7 7.0 10.0 17.7 8.4 15.0
100 8.3 10.9 15.6 9.4 13.4 23.7 11.3 20.0
125 10.4 13.6 19.5 11.7 16.7 29.6 14.1 25.0
150 12.5 16.3 23.4 14.1 20.1 35.5 16.9 30.0
175 14.6 19.1 27.3 16.4 23.4 41.4 19.7 35.0
200 16.7 21.8 31.2 18.8 26.8 47.4 22.6 40.0
225 18.7 24.5 35.1 21.1 30.1 53.3 25.4 45.0
250 20.8 27.2 39.0 23.5 33.5 59.2 28.2 50.0
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