HERS Diagnostic and Field Testing 3

Question 1

What is the primary purpose of performing a combustion safety test during a HERS rating?

Accepted Answer

To identify carbon monoxide spillage or backdrafting risks in combustion appliances

Answer

To verify HVAC system efficiency ratings

Answer

To measure natural gas consumption

Answer

To confirm adequate combustion air supply for the furnace

Question 2

Which test condition is considered 'worst case' for combustion safety testing of atmospherically vented appliances?

Accepted Answer

All exhaust fans on, interior doors closed to maximize depressurization

Answer

All windows open, no exhaust fans running

Answer

All doors open, supply fans running

Answer

Blower door at 50 Pascals, all registers open

Question 3

When using a calibrated manometer to measure pressure difference across the building envelope, the reference port (Channel B) should be placed:

Accepted Answer

Outside in an undisturbed location

Answer

Inside the house near the blower door

Answer

In the attic space

Answer

Adjacent to the return air plenum

Question 4

A HERS rater finds a CO reading of 35 ppm in the flue gases of a natural draft water heater. What is the appropriate action?

Accepted Answer

Immediately notify the homeowner and recommend appliance service before occupancy

Answer

Record the value and continue rating — it is within normal range

Answer

Retest at a different pressure to confirm the reading

Answer

Flag it only if the reading exceeds 100 ppm

Question 5

What does 'spillage' mean in the context of combustion appliance zone (CAZ) testing?

Accepted Answer

Combustion byproducts escaping from the draft hood into the living space

Answer

Gas leaking from supply lines

Answer

Excess condensate draining from high-efficiency equipment

Answer

Air infiltrating through gaps around the flue pipe

Question 6

During a pressure diagnostics test, a rater measures -3 Pascals in a bedroom with the door closed and the HVAC system running. This indicates:

Accepted Answer

Excessive supply airflow to the bedroom relative to return air capacity

Answer

Adequate air balancing in the bedroom

Answer

The bedroom window is leaking

Answer

Return air is located in the bedroom

Question 7

Which instrument is specifically used to measure the airflow of individual supply registers during HVAC diagnostics?

Accepted Answer

Flow hood (balancing hood)

Answer

Blower door

Answer

Duct blaster

Answer

Anemometer