When it comes to diagnosing a restriction in a dryer vent, there is a lot of chatter about the best method to do this. I have actually heard and seen different techniques for diagnosing a restricted dryer vent like camera inspections, checking the airflow with your hand, a visual examination of the vent while running the dryer, and testing the airflow from the termination point with an anemometer. I want to share my blog about my thoughts for each of these techniques and what I consider as the best strategy.
Unless you can actually run the cam the whole length of the duct, you would not be able to figure out whether there is a real restraint. Many of the budget-friendly inspection cameras don't go far more than three feet. Considering the truth that lots of dryer vent runs might be fifteen feet or more, this would not be enough approach to test it. Buying a camera that is suited for sewage system lines and has the ability to run the whole length of the dryer vent might work, however, the high price of these cameras would be thought of as an advantage to this diagnostic technique. In addition, there is an opportunity that running a camera designed for drain lines through an extremely thin duct (often the ducting is incredibly vulnerable due to being improperly installed) might trigger separation of the ducting or puncturing of the ducting inside the drywall or the attic. For these reasons, I think camera inspection is not appropriate and possibly pricey.
Hand and Eye Inspection
This method is done by turning on the dryer and finding the dryer vent termination point. You can put your hand up beside the termination point to feel the airflow while at the same time visually checking the vent cover to see if the air is coming out. The main problem with this approach is that numerous vents duct out on the second level of the building or on the roofing system. This needs lots of time to really get out a ladder and inspect these vents. Also, it does not offer any data to the consumer considering that you are merely relying on your senses. What feels and seems like an excellent airflow to one tech might not be the same for another one.
An anemometer is a gauge for measuring the airspeed. This is an excellent tool for this purpose, however, like the previous technique, it needs you to really access the termination point, it might be located at any place. Secondly, sometimes it can provide a false reading. This was explained by a professional in this field who told to put your thumb over a water tube that has actually been switched on full blast. Basically, the water circulation has actually been restricted (there is less water coming out). However, it provides the wrong feeling that the circulation is better due to you having more pressure and the water tasks out further from the hose. This would be the same for a clogged up dryer vent. You may have a restriction, but never know it since you are still getting what looks like an excellent airflow.
Magnehelic Gauge Inspection
I think this is the most efficient approach for a dryer vent limitation. It is the best one in terms of clear detecting a limitation with good time management and cost-effectiveness. A Magnehelic gauge is a device that is used to determine positive, negative, and differential pressures. The Magnehelic Gauge in terms of vent cleaning is extremely easy to use. A tip is inserted into the shift ducting (the duct that connects the dryer to the ventilation system in the building). The dryer is switched on and the needle registers a reading. In short words, a restricted dryer vent would register around 0.60" water column or higher. In fact, a restriction doesn’t always need to be cleaned up. A limitation is anything that is restricting airflow whether it is because of lint inside the vent, the ducting being broken, too many elbows within the venting, etc. Because many people prefer to have data supporting work necessity, this fits right in line with their expectations. Also, it provides supporting evidence to the franchisee for doing the repair work and upkeeping it.
This gauge is just inserted into the ducting behind the dryer so you don't need to access the termination point of the ducting system. And once the test is done, a simple plastic or rubber cap is placed into the small puncture made in the transition duct. This gadget costs around $50-100 would be a reasonably small investment compared to the payout it provides.
I motivate everybody to do dryer vent cleaning and repair work. In fact, if you’re not checking dryer vents, then you’re actually not fixing the device properly.