Review on 🌡️ Pyle PTHM15 (Black) Indoor Humidity and Temperature Monitor - Portable Digital Hygrometer Thermometer: Moisture Temperature and Humidity Sensor with Dew Point, Wet Bulb Temperature Meter Tester by Robert Oner

Pros: When entering the area it gives a pretty good dew point reading for half a minute. It appears to be within 1% when humidity is measured over saturated salt water. In terms of temperature, relative humidity and dew point, it is almost the same as my wet-bulb thermometer. (Wet-bulb calculations seem a bit unreliable.) Slow-bulb thermometer: The manufacturer says, "Take temperature and humidity measurements on the go with this mini-meter. Fast response time with dual displays provides accurate readings.” Fast response? In my experience, these readings take at least half an hour. The relative humidity depends on the temperature and the thermometer is very slow. I put the shoebox on the table in the middle of the room. I put a counter on the box with a probe sticking up in the air. Next to it I put a piece of paper sticking out next to the probe. With an infrared thermometer, thin paper shows the temperature of the air. An hour later, both paper and meter read 73.9 F. The meter read 63.0% humidity with a dew point of 60.5. After half an hour outside the meter read 65.3 F. I brought it back and checked every 5 minutes. After 15 minutes, she was still 2.2 degrees below zero and 3.9% above zero (71.7 F, 67.9%). The gauge took 30 minutes to reach the desired temperature within one degree and the humidity was 2% higher (73.0 F, 65.0%). After 45 minutes, it was within half a degree and 1.1% humidity (73.4 F, 64.1%). The paper temperature was still 73.9 F. The dew point was still 60.5. Even if the initial difference was only 2.2 F, it would take the thermometer 30 minutes to be accurate to within half a degree. It reacts faster to the fan draft, but still makes you wait a long time. The stem appears to be a thick-walled, chrome-plated metal tube. It and the handle act as a heat sink, a thermal anchor for the probe. The shaft must be a poor conductor of heat to insulate the sensor from the handle. In order to be able to react quickly to temperature changes, the shaft must have a low thermal mass. It doesn't have to be smooth and reflective like a thermos. Poor display: readings have two decimal places. Hundredths seem superfluous. They take up space and make the numbers legible longer. The top row is relative humidity. The bottom line runs through six numbers: F, C, dew point C, dew point F, wet bulb C, and wet bulb F. Captions like "dew point" are in 3-point font! Try reading this through glass in low light! I click on six numbers to find one that is close to my expected value. Why does the user have to keep clicking six numbers on two scales? The screen looks big enough for relative humidity plus three temperatures; You would click to toggle the scales. No labels are needed when you see all three temperatures together. Dew Point Increment: The dew point is displayed in increments of approximately 0.6F. He jumps back and forth sometimes. I don't know why it's programmed to not show the dew point more accurately. With strides that big, I don't see if it's changing. Switch: The meter draws approximately 1 milliamp when on and 85 microamps when off. With 30 one-minute measurements per day, 80% of the energy is consumed in the off state. An alkaline battery lasts about 5 months. With the same usage it would last 2 years if the meter really turns off. There is a cost associated with replacing the 9 volt battery. If you don't have it, it's a major inconvenience. Sunlight: According to the manual, the sensor should not be exposed to direct sunlight. If they want to keep it out of the sun, they should say so. If short-term exposure could be harmful, they should put a cap on the probe to put on before taking it out the door. Color: I bought this meter expecting to be able to take measurements on the go. Instead, I should set him down and walk away while he's slow to respond. Black is an uncomfortable color. When other black objects are nearby or the lighting is dim, it can be difficult to see them. Update: I didn't have to change the batteries as often as I expected. That lasted 3-1/2 years. I replaced it with Mengshen. It also takes a long time to adjust to a different temperature, but I like it much more for a number of reasons.