# About the Inspecting HVAC Systems category **URL:** \ **Category:** Inspecting HVAC Systems\ **Created:** [April 3, 2019, 3:11pm UTC](https://forum.nachi.org/t/about-the-inspecting-hvac-systems-category/151015 "2019-04-03T15:11:55Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![system](https://global.discourse-cdn.com/internachi/original/3X/d/f/df7ced6a9ca05e7c93fa949dfc12a8c10d06c887.png) [@system](https://forum.nachi.org/u/system)\ **Post date:** [April 3, 2019, 3:11pm UTC](https://forum.nachi.org/t/about-the-inspecting-hvac-systems-category/151015/1 "2019-04-03T15:11:55Z")
Topics include heating, venting, and air conditioning inspections. ---
**Author:** ![kselwyn2](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/kselwyn2/32/57038_2.png) [@kselwyn2](https://forum.nachi.org/u/kselwyn2)\ **Post date:** [August 31, 2019, 8:21pm UTC](https://forum.nachi.org/t/about-the-inspecting-hvac-systems-category/151015/2 "2019-08-31T20:21:16Z")
I’m a little confused. I’m new and taking the “Safe Practices” class and am in the “HVAC” section. It says to cut off power to appliance at main shut-off prior to operating thermostat. How is the appliance gonna operate from the thermostat if the power is shut off to the appliance? I’m sure I’m misunderstanding. ---
**Author:** ![lkage](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/lkage/32/347658_2.png) [@lkage](https://forum.nachi.org/u/lkage)\ **Post date:** [November 21, 2019, 4:37pm UTC](https://forum.nachi.org/t/about-the-inspecting-hvac-systems-category/151015/3 "2019-11-21T16:37:33Z")
It is probably a misprint, if it says what you say, Ken. I’m sure they would like to know. You can make contact at [fastreply@internachi.org](mailto:fastreply@internachi.org) with you sending a link for them to find the issue. Larry ---
**Author:** ![kshepard](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/kshepard/32/59504_2.png) [@kshepard](https://forum.nachi.org/u/kshepard)\ **Post date:** [January 10, 2020, 5:04am UTC](https://forum.nachi.org/t/about-the-inspecting-hvac-systems-category/151015/4 "2020-01-10T05:04:39Z")
You typically shut off power at the kill switch for the furnace, not at the service- or sub- panel, then turn up the thermostat, then turn the power back on so you can observe the appliance start-up sequence and watch for changes in burner flame characteristics when the blower is activated that indicate a cracked heat exchanger. ---
**Author:** ![ssadeghi](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/ssadeghi/32/195675_2.png) [@ssadeghi](https://forum.nachi.org/u/ssadeghi)\ **Post date:** [December 18, 2020, 5:36pm UTC](https://forum.nachi.org/t/about-the-inspecting-hvac-systems-category/151015/5 "2020-12-18T17:36:38Z")
I realize this is an older topic, but I had the same question as the original poster. Just so I understand correctly, the purpose of turning off the heating unit’s kill switch, raising the thermostat’s temperature, then activating power to the kill switch, is so you can visually inspect the heater’s full startup routine? That makes waaaaay more sense then the way the text states things! > Use normal operating controls > To avoid dangers from pre-ignition, inspectors may decide to shut off the power to the appliance at the service switch before using the thermostat (normal operating controls). This is not always possible because with some thermostats, shutting off power to the appliance also shuts off power to the thermostat. When this is the case, the inspector should be diligent in accessing the appliance immediately after turning up the thermostat. Some inspectors may begin by inspecting the condition of the appliance. Then, they may turn off the service switch. Then, the thermostat may be activated to turn the appliance on. Then, the inspector may return to the appliance to continue with the visual inspection. ---
**Author:** ![jbennett22](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/jbennett22/32/179684_2.png) [@jbennett22](https://forum.nachi.org/u/jbennett22)\ **Post date:** [November 30, 2022, 7:21pm UTC](https://forum.nachi.org/t/about-the-inspecting-hvac-systems-category/151015/6 "2022-11-30T19:21:23Z")
Hello, I am new to the training/certfication and very excited to learn more about all of these activitie. I have decided that this is the perfect path for me and will do really well at it. I am very sure I will have questions when I am done with this course.