CENWAT Boiler Types 2

Question 1

What is a back boiler?

Accepted Answer

A boiler installed behind a gas fire in a fireplace recess

Answer

A back boiler is installed behind a decorative gas fire in a fireplace recess. They are no longer manufactured new but many remain in existing properties.

Question 2

What is a floor-standing boiler typically used for in UK installations?

Accepted Answer

High-output applications or older properties where wall-hung installation is not practical

Answer

Floor-standing boilers are used for higher output requirements or in older properties where wall-hung installation is not suitable. They tend to be larger and heavier than wall-hung models.

Question 3

What does 'modulating' mean in relation to modern condensing boilers?

Accepted Answer

The boiler varies its heat output to match demand rather than simply switching on and off at full power

Answer

Modulating boilers adjust their burner firing rate to match the actual heat demand, reducing cycling and improving efficiency compared to on/off boilers.

Question 4

What is the purpose of the primary heat exchanger in a boiler?

Accepted Answer

To transfer heat from the burner flame to the heating circuit water

Answer

The primary heat exchanger absorbs heat from the burner flame and transfers it to the water in the heating circuit; in condensing boilers a secondary heat exchanger also captures latent heat from flue gases.

Question 5

In a combi boiler, what happens to the central heating circuit when hot water is demanded?

Accepted Answer

The central heating circuit is temporarily diverted so all heat is prioritised for domestic hot water

Answer

Most combi boilers prioritise domestic hot water demand by diverting the system to the plate heat exchanger for DHW, temporarily suspending the central heating circuit.

ACS CENWAT Practice Test

ACS CENWAT Practice Test

CENWAT Boiler Types 2