I'll shop for meter my phone doesn't support the app , but I just did the ir test for heat like you suggested and I do feel a little heat when I turn them on.I also have an apogee too. Not everyone can or is willing to shell out that kind of coin for a meter. The phone app was close enough when I used it that I never burned a plant. Before the app it just took a lot of grows to learn to read the plants. Fried a few plants along that journey. Point is the app is better then no meter at all.