CENWAT Boiler Types

Question 1

What is the defining characteristic of a combination (combi) boiler?

Accepted Answer

It provides both central heating and instantaneous domestic hot water from one unit with no separate hot water cylinder

Answer

A combi boiler heats water directly from the mains for domestic hot water on demand and also provides central heating, eliminating the need for a separate hot water storage cylinder.

Question 2

What type of boiler requires a cold water storage cistern and a hot water storage cylinder?

Accepted Answer

Conventional (regular/heat-only) boiler

Answer

A conventional (regular or heat-only) boiler requires a separate cold water storage cistern in the loft and a hot water cylinder, making it suitable for properties with existing traditional systems.

Question 3

What is a system boiler?

Accepted Answer

A boiler with the pump, expansion vessel and safety devices built in, requiring only a hot water cylinder

Answer

A system boiler has key system components (pump, expansion vessel, PRV) built in and requires only a separate unvented or vented hot water cylinder, simplifying installation.

Question 4

What is the primary efficiency advantage of a condensing boiler over a non-condensing boiler?

Accepted Answer

It recovers latent heat from flue gases by condensing water vapour, achieving efficiencies above 90%

Answer

Condensing boilers use a secondary heat exchanger to extract latent heat from water vapour in the flue gases, which would otherwise be wasted, achieving seasonal efficiencies above 90%.

Question 5

Since April 2005, what type of boiler is required by UK Building Regulations for new installations and like-for-like replacements?

Accepted Answer

Condensing boiler

Answer

Since April 2005, Building Regulations Part L have required that replacement and new gas boilers in England and Wales must be condensing boilers, with very limited exceptions.

ACS CENWAT Practice Test

ACS CENWAT Practice Test

CENWAT Boiler Types