CENWAT Central Heating System Design 4

Question 1

What is the purpose of zone valves in a central heating system?

Accepted Answer

To independently control heating and hot water circuits

Answer

Zone valves (motorised valves) open and close to direct hot water flow to separate circuits such as heating and hot water, allowing independent control via separate thermostats.

Question 2

Which component in a central heating system controls the time that heating comes on and off?

Accepted Answer

Programmer or timer

Answer

A programmer or timer controls when the heating and hot water circuits are active, setting on/off periods throughout the day.

Question 3

What does 'commissioning' a central heating system involve?

Accepted Answer

Setting up, testing and adjusting the system to operate correctly to design specification

Answer

Commissioning includes flushing, filling, venting, pressure testing, setting controls, balancing radiators, and verifying the system meets design performance before handover.

Question 4

What is the purpose of power flushing a central heating system?

Accepted Answer

To remove sludge, corrosion products and scale from the pipework and components

Answer

Power flushing uses a high-flow, low-pressure machine with chemicals to dislodge and remove accumulated sludge, rust and scale, restoring system efficiency.

Question 5

What chemical is commonly added to a central heating system to prevent corrosion?

Accepted Answer

Corrosion inhibitor (e.g., Sentinel X100 or Fernox F1)

Answer

A corrosion inhibitor such as Sentinel X100 or Fernox F1 is dosed into the system water to protect metals from corrosion and prevent the formation of magnetite sludge.

ACS CENWAT Practice Test

ACS CENWAT Practice Test

CENWAT Central Heating System Design 4