PlumbRevise
Sign in
Level 3 · Plumbing revision

Hot Water revision notes

System selection, demand and storage sizing, reheat times, scald protection and fault diagnosis.

Start reading Practice questions
  • 12notes with free previews
  • 94questions on Premium
  • 5topics

System Selection & Design

  1. Instantaneous and stored hot water comparedTrade-offs between heating water on demand and storing it in a cylinder. Premium
  2. Secondary circulation and cylinders for solar and heat pumpsKeeping hot water close to distant outlets, and how solar and heat-pump cylinders differ. Premium
  3. Vented and unvented hot water: choosing the systemHow open-vented and unvented stored hot water systems differ and what drives the choice at Level 3. Premium

Sizing & Storage Calculations

  1. Cylinder reheat and recovery time (worked example)Turning a coil or element power rating into how long a cylinder takes to recover. Premium
  2. Energy to heat a cylinder (worked example)Applying Q = m x c x change in T to find the energy and time to heat stored water. Premium
  3. Estimating hot water demand and sizing a cylinderA structured way to estimate daily and peak hot water demand and pick a storage volume. Premium

Design Temperatures & Scald Protection

  1. Design temperatures and dead-leg controlWhy hot water is stored at 60 °C, distributed hot, and how dead legs are limited. Premium
  2. Thermostatic mixing valves and scald protectionSelecting, commissioning and maintaining TMVs; the bath ceiling and lower limits for vulnerable users. Premium

Commissioning & Fault Diagnosis

  1. Commissioning hot water systems and recording itThe operational checks and documentation needed to bring a hot water system into safe service. Premium
  2. Diagnosing hot water faultsA systematic approach to common stored hot water defects and how to reason from symptom to cause. Premium

Handover & Maintenance

  1. Handover and manufacturer servicing schedulesWhat to demonstrate and hand over to the user, and how manufacturer schedules drive servicing. Premium
  2. Legionella control and maintenance recordsRoutine measures and record-keeping that keep stored hot water safe from bacterial growth. Premium

Connect hot-water demand to storage and recovery

Work through hot-water sizing questions by recording the demand, usable storage and heat available for recovery. Explain why a cylinder volume and a heater power answer different questions. Keep the stated temperatures and units visible throughout the working.

Use the cylinder heat-up calculator to check energy and time, then the unvented-cylinder diagram to trace the controls. The G3 discharge guide covers the safety route that must be considered alongside storage and heating.

More Plumbing modules

Every module has its own revision notes and question bank.

Cold Water SystemsScientific PrinciplesHot Water SystemsCentral HeatingDrainage & SanitationRainwater SystemsHealth & SafetyCommon Plumbing ProcessesElectrical Safety & IsolationField DiagnosticsLow-Carbon & RenewablesCSCS & Site SafetyCentral Heating (L3)Cold Water (L3)Domestic Fuels (L3)Sanitation & Drainage (L3)