Documenting before-and-after dryer-vent airflow

Keep the comparison consistent

Where safe and appropriate for the equipment and instrument, take the before reading before work and the after reading after work at the same measurement point. Use the same instrument, measurement method, units, device mode or range, and dryer operating settings. Record the exact point and instrument position; “outside” alone may not identify a repeatable location.

Follow the dryer and instrument instructions and your training. Do not reach into moving equipment, remove protective parts, operate equipment in an unsafe condition, or climb to an inaccessible termination just to obtain a number. If a reading cannot be taken safely, leave it blank and explain why.

Record the conditions alongside each value

• Value and unit: copy the actual displayed reading and unit. Retain useful precision without adding digits the instrument did not provide.
• Location and method: identify the termination or other measurement point, probe position, and whether the reading is a spot value or an average. For averages, record the sampling method and duration.
• Instrument: record its model or identifier and relevant mode, range, or device settings. Record calibration information only if known.
• Dryer conditions: note the operating cycle or setting and relevant load conditions. Note any changed damper position, attachment, weather, or other condition that may affect the comparison.
• Limits: describe restricted access, fluctuating readings, or a changed setup. If methods differ, label the values as separate observations and avoid presenting a percentage as a like-for-like improvement.

CFM measures volume flow. Feet per minute (ft/min) and metres per second (m/s) measure velocity. Do not compare unlike units directly or relabel a velocity reading as CFM. Deriving volume flow requires an appropriate area and method; do not invent a conversion.

How VentProof keeps the record

VentProof has fields for before airflow, after airflow, unit (CFM, ft/min, or m/s), and measurement location. Put the method, instrument, settings, and changed conditions in the location/method field or technician notes. These are documentation fields, not an automated test procedure or instrument integration.

Leave an unavailable reading empty; do not enter zero as a placeholder. VentProof’s report describes blank readings as not measured. Where a percentage change is shown, it is arithmetic relative to the before value, not a pass/fail decision. A missing or zero before value does not provide a meaningful percentage baseline.

Explain what the readings establish

A higher after reading under comparable conditions records a measured change. It does not certify safety, establish code compliance, prove a concealed vent is clear, or replace inspection and equipment instructions. This guide supplies no universal target or safety threshold.

Pair the measurements with captioned before-and-after photos and actual work from the service report checklist. See the fictional report for layout, or use the blank report template on paper. If access was unavailable, follow the failed-access guide instead of inventing readings.