To be comfortable in using an infrared camera you need to be familiar with two types of heat transfer and three modes of heat transfer. I’ll talk about the three modes of heat transfer (conduction, convection and radiation) in a future blog. The two types of heat transfer are steady state and transient. Steady state heat flow is constant with time. An example could be a fully warmed up motor or a building that is not influenced by exterior or interior heating/cooling. One of the important questions a thermographer will want to ask (if he or she is using an IR camera for building diagnostics) is: “Is the sun affecting any of the walls of this building?” Picture a day with clear skies with the sun shining brightly. You will experience “transient” heat flow throughout the day. The sun warms the east wall first, then the south wall, and then the west wall. And as the ambient temperature is rising or falling all walls, including the north wall, are being affected throughout the day. The HVAC system can also be affecting the walls. A thermographer must be aware of which wall he or she is looking at and how it is being affected by exterior or interior influences. Your investigation using thermal imaging to locate missing or compromised insulation is affected by the ∆T of the walls, outside surface temperature verses inside surface temperature. That delta T can be constantly changing due to transient heat transfer. Monitor closely both surfaces, the one you are looking at and the other side to verify the minimal requirements.
Example of TRANSIENT HEAT TRANSFER throughout the day and the solar effects on the building!
How’s your comfort level in thermography?
(The above comments represent my opinion).
Rod Hoff / Restoration Consultants Inc
Thermography Instructor / IR camera sales
3284 Ramos Circle, Sacramento CA 95827
toll free 888-617-3266 ext 301
Provider of Fluke TiS, TiR, TiR1, Ti, Ti25, TiR27, Ti27, TiR29, Ti29, TiR32, Ti32, TiR3, and TiR4 infrared cameras.
See DEMO www.moistureview.com/demo.html