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Domestic Hot Water

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

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Hot Water Cylinders

Safety Controls

Boiler Interlock

  • Building Regs 2002 - Part L
  • the boiler and pump are switched off if there is no heat demand
  • Floor area is up to 150m2 - at least 2 space heating zones with independent temperature control (one is assigned to living area)
  • Floor area is greater than 150m2 - at least 2 space heating zones with separate timing and temperature controls
  • Single-storey open-plan (leaving area is greater than 70%) - sub-zoning is not appropriate
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Heating Zones

  • separate hot water zone in addition to space heating zone for all dwellings (not required for instantaneous heaters)
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Timing Controls

  • Full Programmer with separate timing to each circuit OR
  • Two or more separate timers for each circuit OR
  • Programmable room thermostats to the heating circuits with separate timing of the hot water circuit
  • ONLY time control for space heating zones is required in case of instantaneous heater
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Tempearture Controls

  • Space Heating
    • Room Thermostats or Programmable Room Thermostats in all zones
    • Thermostatic Radiator Valves TRV's on all radiators (other than with thermostat and bathrooms)
  • Domestic Hot Water
    • Cylinder thermostat
      Cylinder thermostat
      • connected 1/3 up from the bottom of the cylinder
      • set at 60-65°C
      • controls a Motorised Valve
    • if greater than 150m2 - more than one hot water circuit:
      • multiple heating zone programmers
      • a single multi-channel programmer
      • separate timers for each circuit
    • NO non-electric controls should be used
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