CENWAT Central Heating System Design 1 — Questions and Answers
Question 1: What is the primary purpose of a central heating system in a UK domestic property?
- To distribute heat from a single source throughout the building (Correct answer)
- To provide localised heating in individual rooms only
- To solely heat domestic hot water
- To ventilate the property
Correct answer: To distribute heat from a single source throughout the building
A central heating system distributes heat generated from a single source (usually a boiler) throughout the building via a network of pipes and radiators.
Question 2: Which pipework layout uses a single pipe that connects all radiators in sequence?
- One-pipe system (Correct answer)
- Two-pipe system
- Microbore system
- UFH manifold system
Correct answer: One-pipe system
A one-pipe system uses a single pipe from which all radiators are connected in series; water flows through the loop and each radiator taps off it.
Question 3: In a sealed central heating system, what component absorbs expansion of water when heated?
- Expansion vessel (Correct answer)
- Feed and expansion cistern
- Pressure relief valve
- Air separator
Correct answer: Expansion vessel
An expansion vessel contains a pressurised bladder that accommodates the increase in water volume as the system heats up, maintaining stable pressure.
Question 4: What is the recommended system design working pressure for most sealed domestic central heating systems?
- 1–1.5 bar when cold (Correct answer)
- 3–4 bar when cold
- 0.1–0.3 bar when cold
- 5–6 bar when cold
Correct answer: 1–1.5 bar when cold
Most domestic sealed systems are charged to 1–1.5 bar when cold, rising slightly when hot but remaining below the pressure relief valve set point.
Question 5: Which document provides the primary design guidance for central heating installations in the UK?
- BS EN 12828 (Correct answer)
- Part L of Building Regulations
- Gas Safety (Installation and Use) Regulations 1998
- CIBSE Guide B
Correct answer: BS EN 12828
BS EN 12828 is the European standard for heating systems in buildings and provides design guidance for hot water central heating systems.
Question 6: What term describes the difference in temperature between flow and return pipes in a central heating system?
- Delta T (ΔT) (Correct answer)
- System pressure differential
- Hydraulic head
- Mean water temperature
Correct answer: Delta T (ΔT)
Delta T (ΔT) is the temperature difference between the flow and return. A typical design ΔT for UK heating systems is 20°C (e.g., 80°C flow, 60°C return).
CENWAT Central Heating System Design 1
What is the primary purpose of a central heating system in a UK domestic property?