CENWAT Boiler Types 4

Question 1

What is a condensate pipe on a condensing boiler?

Accepted Answer

A pipe that drains acidic condensate produced by flue gas cooling from the boiler to a drain

Answer

Condensing boilers produce acidic condensate (approximately pH 3–4) as a by-product of recovering latent heat; this must be drained safely via a condensate pipe to an approved drain.

Question 2

Why must condensate pipes on external runs be insulated?

Accepted Answer

To prevent freezing in cold weather which can cause the boiler to lock out

Answer

External condensate pipes are prone to freezing in cold weather, which blocks condensate drainage and causes the boiler to lock out on a fault code; insulation prevents this.

Question 3

What is the minimum internal diameter recommended for a condensate discharge pipe?

Accepted Answer

22 mm for external runs, 19 mm for internal

Answer

HHIC and manufacturer guidance recommends 22 mm minimum for external condensate runs to reduce freezing risk, with 19 mm acceptable for short internal runs.

Question 4

What type of material is NOT suitable for condensate pipework due to its reaction with acidic condensate?

Accepted Answer

Copper or galvanised steel

Answer

Condensate is acidic (pH ~3–4) and will corrode copper or galvanised steel pipework. Plastic materials such as ABS, PVC or polypropylene must be used for condensate discharge pipes.

Question 5

A boiler displays a fault code and stops operating in cold weather. What is the most likely cause?

Accepted Answer

Frozen condensate pipe

Answer

In cold weather, a frozen condensate pipe is the most common reason for boiler lockout. The boiler detects a blockage in condensate drainage and shuts down safely.

ACS CENWAT Practice Test

ACS CENWAT Practice Test

CENWAT Boiler Types 4