CENWAT System Controls and Zoning 3

Question 1

What is the purpose of a boiler interlock in a central heating system?

Accepted Answer

To prevent the boiler from firing when there is no thermostat demand for heat

Answer

To regulate the gas valve opening pressure

Answer

To control the flue gas recirculation temperature

Answer

To monitor inhibitor concentration in the system

Question 2

To meet HSE guidance on Legionella prevention, what minimum temperature should a domestic hot water cylinder thermostat be set to?

Accepted Answer

60°C

Answer

50°C

Answer

55°C

Answer

65°C

Question 3

Where on a hot water cylinder should a cylinder thermostat be positioned?

Accepted Answer

Approximately one-third of the way up from the bottom

Answer

At the very top of the cylinder

Answer

At the very bottom of the cylinder

Answer

At the exact mid-point of the cylinder height

Question 4

What is the function of a frost thermostat in a domestic central heating system?

Accepted Answer

To automatically activate the heating when ambient temperature drops near freezing, protecting pipework

Answer

To prevent the boiler from overheating during summer months

Answer

To control the temperature of water in the expansion vessel

Answer

To switch the programmer to winter mode automatically

Question 5

How does an optimum start controller differ from a standard heating programmer?

Accepted Answer

It uses indoor and outdoor temperature sensors to calculate the latest start time needed to reach comfort temperature by the set time

Answer

It can only be programmed for weekdays

Answer

It controls both heating and hot water on a single channel only

Answer

It automatically adjusts boiler output but not start time

Question 6

Under 'Boiler Plus' regulations introduced in England from April 2018, what additional efficiency measure must be included with a new combi boiler installation?

Accepted Answer

At least one of: weather compensation, load compensation, flue gas heat recovery, or a smart thermostat with automation

Answer

A minimum two-zone heating system with separate programmers

Answer

An external temperature sensor connected directly to the boiler only

Answer

A TRV on every radiator including the bathroom radiator

Question 7

What does BS EN 12831 provide in the context of central heating system design?

Accepted Answer

The standard method for calculating building heat loss to correctly size heating systems

Answer

Installation requirements for gas appliances

Answer

Testing procedures for unvented hot water storage vessels

Answer

Guidance on flue gas analysis and combustion efficiency