RMS Diagnostic Testing & Troubleshooting 1 — Questions and Answers
Question 1: What is the primary purpose of performing diagnostic testing before installing a radon mitigation system?
- To determine optimal sub-slab communication and suction point locations (Correct answer)
- To calculate the home's total square footage
- To measure indoor air quality for other pollutants
- To verify the building's electrical capacity
Correct answer: To determine optimal sub-slab communication and suction point locations
Diagnostic testing identifies where suction points should be placed by assessing sub-slab communication and soil permeability.
Question 2: During a pressure field extension test, a manometer is inserted into a diagnostic hole. What result indicates good sub-slab communication?
- A positive pressure reading at the diagnostic hole
- A negative pressure reading similar to that at the suction pit (Correct answer)
- No pressure change at the diagnostic hole
- A reading of exactly zero pascals
Correct answer: A negative pressure reading similar to that at the suction pit
A negative pressure reading at the diagnostic hole similar to the suction pit pressure confirms the sub-slab is well-interconnected.
Question 3: A smoke pencil or puffer is used during radon diagnostic testing primarily to:
- Test for carbon monoxide leaks in the gas line
- Identify air pathways and verify airflow direction around the foundation (Correct answer)
- Measure radon concentration in soil gas
- Calibrate a continuous radon monitor
Correct answer: Identify air pathways and verify airflow direction around the foundation
A smoke pencil visualizes airflow patterns to identify where soil gas may be entering and whether the system is drawing air effectively.
Question 4: When probing multiple diagnostic holes, what finding indicates that a second suction point is necessary?
- All holes show equal negative pressure
- One or more sections show no negative pressure response (Correct answer)
- The fan is drawing too much current
- Radon levels drop after installing the first suction point
Correct answer: One or more sections show no negative pressure response
Areas that show no pressure response are isolated from the suction point and require their own dedicated suction pit.
Question 5: A mitigation fan is operating but post-mitigation radon tests show levels above 4 pCi/L. Which diagnostic step should be performed first?
- Replace the fan immediately
- Check for air bypasses such as open sumps, cracks, or uncapped drains (Correct answer)
- Install additional fans in series
- Increase the fan exhaust height
Correct answer: Check for air bypasses such as open sumps, cracks, or uncapped drains
Air bypasses allow soil gas to enter the living space even when the system is running, and are the most common cause of persistent elevated radon post-installation.
Question 6: What does a U-tube manometer permanently installed on a mitigation system allow a homeowner to monitor?
- The indoor radon concentration level
- Whether the fan is maintaining negative pressure in the suction pipe (Correct answer)
- The outdoor radon concentration
- Fan motor operating temperature
Correct answer: Whether the fan is maintaining negative pressure in the suction pipe
The U-tube manometer provides a visual indicator that the system is functioning by showing fluid displacement corresponding to negative pressure in the pipe.
Question 7: When troubleshooting a system that has lost vacuum while the fan continues running, which component should be inspected first?
- The electrical panel breaker
- The suction pipe for cracks, disconnections, or blockages (Correct answer)
- The radon test kit expiration date
- The exterior concrete slab surface
Correct answer: The suction pipe for cracks, disconnections, or blockages
Physical disconnections, cracks, or obstructions in the suction pipe are the most common mechanical cause of vacuum loss in an otherwise running system.
RMS Diagnostic Testing & Troubleshooting 1
What is the primary purpose of performing diagnostic testing before installing a radon mitigation system?