HERS Combustion Safety 2

Question 1

What is the primary purpose of a combustion appliance zone (CAZ) depressurization test?

Accepted Answer

To determine if the zone becomes sufficiently depressurized to cause backdrafting

Answer

To measure the BTU output of the appliance

Answer

To check the flue gas temperature

Answer

To verify the gas pressure at the manifold

Question 2

Which of the following conditions represents a 'worst-case' scenario during a CAZ depressurization test?

Accepted Answer

All windows and doors closed, all exhaust fans on

Answer

All windows and doors open, all exhaust fans off

Answer

Only the furnace running with windows open

Answer

Only the water heater running with fans off

Question 3

A atmospherically vented water heater fails a steady-state spillage test. What does this indicate?

Accepted Answer

Combustion gases are spilling from the draft hood into the living space

Answer

The water heater is over-firing

Answer

The anode rod needs replacement

Answer

The thermostat is set too high

Question 4

What CO concentration threshold (ppm) in undiluted flue gases typically triggers a 'fail' rating during a HERS combustion safety inspection?

Accepted Answer

400 ppm

Answer

50 ppm

Answer

200 ppm

Answer

800 ppm

Question 5

Which diagnostic tool is most appropriate for detecting combustion gas spillage at a draft hood?

Accepted Answer

Combustion analyzer or smoke pencil

Answer

Blower door manometer

Answer

Infrared camera

Answer

Duct blaster

Question 6

A sealed-combustion furnace draws combustion air directly from outside. How does this affect CAZ depressurization concerns?

Accepted Answer

It eliminates CAZ depressurization risk for that appliance since it does not use zone air

Answer

It increases CAZ depressurization risk because more air is consumed

Answer

It has no effect on CAZ depressurization

Answer

It only reduces risk if the flue is also sealed

Question 7

What is the purpose of a draft pressure test on a natural-draft appliance flue?

Accepted Answer

To verify the flue is creating adequate negative pressure to remove combustion gases

Answer

To measure the heating efficiency of the appliance

Answer

To check for gas leaks in the heat exchanger

Answer

To calibrate the thermostat