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AcuRite 00613 Humidity Monitor with Indoor Thermometer, Digital Hygrometer and Humidity Gauge Indicator
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- Indoor thermometer displays temperature in Fahrenheit or Celsius
- Humidity gauge shows the comfort level of your home, based on current humidity level
- Track conditions throughout the day with the high and low records to ensure a healthy home
- Humidity meter features a magnet-mountable design, fold-out stand and clip; Powered by (1) AA battery (not included)
- Includes limited 1-year warranty; Knowledgeable US-based customer service team
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From the manufacturer
Indoor Comfort Conditions - At a Glance
No More Guessing at the Ideal Temperature and Humidity
The humidity gauge quickly shows you whether the current indoor humidity level is too high, low or is OK for optimal comfort.
Daily Insights into Your Home Environment
Is your heating and cooling system running efficiently throughout the day? Is it getting too dry in the nursery? The display shows 24-hour records of the highest and lowest temperature and humidity readings of the day, so you can take action.
Fits into Every Room of the Home
Small enough to fit just about anywhere, the AcuRite digital thermometer & hygrometer blends right in to provide useful indoor comfort conditions at a glance.
Versatile, Portable Design
Pocket-Sized for Portability
No wider or taller than a deck of cards, the AcuRite temperature and humidity monitor is perfect for leaving in the home or taking with you on-the-go.
Stand Folds Out for Tabletop Use and Clips to Your Backpack
Whether you need to know the current temperature and humidity of your living room or the current conditions while on your hiking trip, the temperature and humidity meter works for your lifestyle.
Save Countertop Space - Mounts Directly to Your Fridge
The magnetic backing allows you to mount the display to metal surfaces where space may be limited. Mount to your HVAC duct next to your dehumidifier or stick to your fridge for at-a-glance viewing.
The Perfect Companion to your Humidifier and Dehumidifier
|AcuRite 00613 Digital Thermometer with Humidity Gauge||AcuRite 01083 Pro Accuracy Digital Thermometer with Humidity Gauge||AcuRite 01080 Pro Accuracy Digital Thermometer with Humidity Gauge|
|Temperature Range||32° to 122° F; 0° to 50° C||-4° to 158° F; -20° to 70° F||-4° to 158° F; -20° to 70° F|
|Temperature Accuracy||+/- 2° F||+/- 0.5° F||+/- 0.5° F|
|Humidity Range||16% to 98% RH||1% to 99% RH||1% to 99% RH|
|Humidity Accuracy||+/- 3%, from 21% to 80% RH||+/- 2% RH||+/- 2% RH|
|Measurement Frequency||Every 15 seconds||Every 10 seconds||Every 10 seconds|
|High/Low Records||24 hours||24 hours, all-time||24 hours, all-time|
|High/Low Humidity Alarm||✓|
|Mounting Options||Fold-out table stand, mounting clip, magnetic back||Tabletop design, wall hanging hole, magnetic back||Table stand, wall hanging hole, magnetic back|
|Dimensions||3" H x 2.5" W x 1.3" D||3" H x 2.5" W x 0.9" D||4" H x 3.75" W x 1.25" D|
The AcuRite 00613 Indoor Humidity Monitor provides all the home comfort information you need, at a glance. Featuring a precision indoor thermometer and hygrometer, and an easy-to-read LCD display, it shows current indoor humidity and temperature, plus daily high and low records. A handy home comfort icon makes it effortless to tell if your indoor humidity is too high, too low, or "OK." Multiple mounting options include a convenient clip, magnets for attaching to a metal surface like a refrigerator, or you can stand it upright on a tabletop. Limited one-year warranty. It's more than accurate, it's AcuRite.
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The procedures I used to do a comprehensive calibration are given below.
Using these two saturated solutions, my measurements on the AcuRite I bought showed that for temperature from 39 deg F to 79 deg F and for relative humidity from 29% to 75% , the max error is 3% off in humidity occurred at very low temperature (39 deg F) (i.e 37%RH is actually 40%) and near room temperature, the error is only 1%RH. (Lucky me!)
Actually, the AcuRite is both a digital humidity monitor (hygrometer) and a digital thermometer. The AcuRite I tested is surprising accurate over a practical range of temperatures and a practical range of relative humidity values (see details given below). The temperature reading is also quite accurate. It is very desirable to have a high accuracy humidity monitor and thermometer for use at home. In the summer, a high humidity house is uncomfortable. Worse yet, a humid basement smells foul allowing mold to grow and humid closets cause clothes to smell bad - a nightmare for many housewives. Knowing accurately the humidity allows one to take measure to lower it. With seemingly high accuracy, the AcuRite is surprisingly cheap.
The comfortable relative humidly(RH) range to human body is recommended to be a region around 45%. American Society of Heating, Refrigerating and Air-conditioning Engineers Inc. (ASHRAE) recommends:
---RH ---------temperature ---- season
30- 60%----- 68-75degF -------winter
30- 60%----- 73-79degF ------summer
"Elevated relative humidity can promote the growth of mold, bacteria, and dust mites, which can aggravate allergies and asthma" and "Relative humidity levels above 70% may lead to the development of condensation on surfaces and within the interior of equipment and building structures. Left alone, these areas may develop mould and fungi." Typically, room temperature is set at 70degF. Also I preferred a RH of 50%. At 45%RH, I feel dry and my skin starts to wrinkle.
Sodium Chloride saturated solution is commonly used to calibrate a hygrometer (humidity monitor) at room temperature (70 deg F) which should give 75%RH. Thus the hygrometer needs to be calibrated again with another source with lower RH, such as Calcium Chloride (31.5% RH at 70 deg F) or Magnesium Chloride (33%RH at 70 deg F). If the hygrometer agrees with one of these values then one can assume it is accurate around 50% RH. If the hygrometer is used only at room temperature, it only needs to be calibrated by two saturated solutions (for example sodium chloride and calcium chloride). However, I have calibrated from 39 to 79 deg F.
Table salt (sodium chloride) and driveway ice melt (calcium chloride) provide an inexpensive and convenient way to calibrate (or check accuracy) of a hygrometer over a range of temperatures and humidity values. I have calibrated my AcuRite unit by using sodium chloride and calcium chloride saturated solutions, each of which was placed in a ziplock bag together with the AcuRite.
An accurate hygrometer is expensive and bulky and I was surprised at the seemingly high humidity accuracy of the Acurite which I purchased from Amazon. The attractive features of the AcuRite are: seemingly very accurate humidity and temperature readings across a useful range of humidities and temperatures(see calibrations given below), records the max and min humidity and temperature occurred within 24 hr interval and low cost. Also the display font for humidity is large enough for convenient viewing. These features are not expected from a $10 device.
Calibration using saturated table salt (sodium chloride) solution
Calibration is based on published measurements of equilibrium relative humidity(RH) vs temperatures above saturated salt solution by scientist(s). I will use these published RH values as standard. For table salt saturated solution, the published RHs, given below, surprisingly are almost a constant from 32 to 104 degF(the measurement increment was 5 degC).
Temp (deg F) RH(%)
I found that there was no different from using table salt with and without iodine. So I used the former. I also found that salt slurry did not work well. I sealed the AcuRite and two plastic cups in a ziplock bag which was further sealed by Scott tape. Each cup has at least 1/8 inch of undissolved salt (at the highest temperature of measurement) with at least 1/8 inch of water above it. Each deg F change can cause 3% change in RH. Since the AcuRite with battery is a big thermal mass, I made sure that for each measurement, the temperature and RH were stable for at least 1/2 hr, a condition which turned out to be most difficult to meet. Measurement results are given below. I found that for temperature, the AcuRite seems to be about 1 deg F higher than another temperature meter which has fractional deg F. However, I will use the temperature displayed by the AcuRite. Low temperature measurements were taken in a refrigerator. It took about one week to do all the measurements.
Temp (deg F) RH(%, measured) RH(%, from standard) Error(%)
41 74 76 -2
72 75 75 0
75 77 75 +2
77 76 75 +1
88 77 75 +2
90 76 75 +1
From the above table, at room temperature of 72 deg, the error is zero and from 41 to 90 deg F, the max error is 2%RH. I would say this is quite acceptable for home use. Next, I checked if the humidity is linear over a range of RH values and a range of temperatures by using another saturated salt solution.
Calibration using saturated calcium chloride (CaCl2) solution at low humidity
A better and purer source for calibration at low humidly is magnesium chloride. Over its saturated solution, the RH is 33% over practical temperature range. Pure Magnesium Chloride is available from amazon or ebay sellers. Another good source to use is Potassium Carbonate which another reviewer in this forum had used and which is also available from amazon or ebay. The equilibrium RH is 43% from 0 to 30 degC. However, I didn't want to spend the money and trouble to get them.
I found that I have some Prestone Driveway Heat ice melter (available from Home Depot and Lowes) which turned out to be Calcium Chloride. But the purity of the source was unknown and this would cast doubt on the results. From the internet, I found that the published equilibrium relative humidity(RH) vs temperatures above saturated calsium chloride solution are:
Temp (deg F) 41 50 59 68 77
RH(%) 40.0. 38.0. 35.0. 32.0 29.5
RH vs temp seems to be linear and the slope is bout -0.3%RH per deg F
My measurement results are:
Temp (deg F) RH(%, measured) RH(%, from standard) Error(%)
39 37 ~40 -3
79 28 ~29 -1
Thus at each temperature, there are now two data points.
If the calcium chloride measurements were believable due to the unknown purity of the calcium chloride source, then the linearity of the humidity of Acurite over a temperature range from 39 to 79 deg F and over a humidity range from 29% to 75% is quite good for home use as the max error is less than 3%RH occurred at 39 deg F, which is too low for normal use. Near Room temperature , however, the error is about 1%RH, which is remarkably small.
I believe that the humidity detector is polymer on a capacitor. Capacitor is a linear device and should response linearly to humidity absorbed. Thus for each temperature if two measured data points agreed with published data by other scientists, then it is sufficient to determine the accuracy and linearity at that temperature. I have verified the data agreement from 39 to 79 deg F. (Note that the calcium chloride purity is questionable. But the measured data did agree with published values.) Thus, within this temperature range, the AcuRite unit I bought seems to be accurate and linear. Ideally, one would like to further calibrate the unit with magnesium nitrate saturated solution which has a RH of 50-55% across practical temperatures. This would give three data points on a straight line to verify the linearity. However, I do not know how to get it easily and cheaply.
In Summary: for temperature from 39 deg F to 79 deg F and relative humidity from 29% to 75% , the max error is 3% off in humidity occurred at very low temperature (39 deg F) (i.e 37%RH is actually 40%) and near room temperature, the error is only 1%.
After I wrapped the AcuRite in a wet paper tower, the humidity was 99%, the expected value.
Update rate and modify the back cover to increase airflow through the unit
For normal use, no modification is need as modification does not change the accuracy of humidity and temperature. Allowing more airflow than necessary may shorten the life of the unit by quicken the contamination of the humidity detector inside the unit. Modification only changes the response time when the humidity changes. For home use, the humidity and temperature are not expected to change so fast that the unit could not keep up.
The unit updates the humidity and temperature about every 15 sec. After initial testings which showed that the unit was accurate, I invested time to modify the cover of the unit as the airflow through the unit is through a grill and could be increased to have a faster response time. Steps for the modification are given below:
1) The cover is held by 4 small screws. Remove them by a jewelry screw driver.
2) Separate the back cover from the main body gently and not too far apart as there is a ground wire of the battery housing connecting the two.
3) Remove the ground wire from the battery housing. Now the two parts can be separated.
4) There is a plastic stick used for changing deg C to deg F. It will fall out but is easy to put back during re-assembly.
I drilled four 3/16 inch holes on each side of the back cover as well as one 3/16 inch at the center of the back cover.
The above measurements were done on just one AcuRite which I bought. Because measured data points seem to agree with published values by other scientists, I am satisfied that the humidity and temperature of my unit are accurate and use it with confidence. However, beware that there are a large number of reviews in this forum who said their AcuRite is no good.
One star off for the house icon show high when the humidity level is ok. There are many reviewers complained about this.
Another star off , even after 2 salt tests, I still doubt it's accuracy. As pics, the first test gave 72%rh and second test was 73%rh. The problem was , I been using it for a week before salt test the lowest I got was 21%rh, after the salt test the first night it gave 16%rh. Before the salt tests, the low usually around 21-25%rh now it is 16% for a few nights already.
Since I have only one unit there is nothing to compare if base on the salt test this unit is considered accurate. And also temp compare to my trusted thermometer.
For the salt test, you need to use air tight container if you use zip lock bag, it might not air tight or leak. The container should not be too big just big enough to fit the meter and salt cup. The salt itself just damp like wet sand not covered with water. Some said fill water covered the salt that is
wrong. Put about 1 tbs of salt in a small cup and wet it with water put in small air tight container wait for 24hr. How fast the read out it will depend on the meter itself for accurate reading wait 12-24hr.