Calibrating Model 613 Hygrometer

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A few days ago, I replaced an ailing hygrometer on my orchid bench with an AcuRite 613. I'm surprised at the divergence between this model's readings and the readings I got with two previous models in the same location.

It's an enclosed location with a 400-watt HID grow light about five feet away; the luminance at the instrument is about 1500 foot-candles. It's near some plants but there's plenty of room for air to circulate and a ceiling fan that runs constantly. Humidity record is 63 to 76 percent with temperature 63 to 72 degrees F. The temp record is fairly consistent with what previous instruments have shown, but the humidity is way higher. Previously I've seen the humidity drop into the forties when the light comes on and I've had to use a vaporizer to keep it above 50%. Humidity outside this basement room in winter is normally below 50%.

Is there a way to calibrate this instrument or test it for reliability?
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Anan Isapta

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Posted 3 weeks ago

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AcuRite Rachell, Employee

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Hello Anan,
The accuracy standard for this product is +/-2°/5% per unit. When comparing this unit side by side with a unit of known accuracy you can show up to a 4°/10% difference. Please verify you are using the battery recommendations listed below. This model does not have a calibration option.

Batteries:

•Verify you are using fresh alkaline batteries or lithium batteries (when temperature is below -4°F/-20°C) in sensor.

•Quality brand batteries are recommended, including Duracell, Rayovac, Energizer, or Kirkland.

•Verify batteries are fresh. The battery expiration date should be at least 6 years out. Batteries can lose 3% power or more every year in storage.

•Heavy duty, extra strength or generic / store brand batteries are not recommended for use with AcuRite products because they may cause performance irregularities due to the way these types of batteries disperse power. Each battery should not exceed 1.6 volts.

•Rechargeable batteries are not recommended for use with AcuRite products because they may cause performance irregularities due to the voltage instability of these types of batteries.

•Mixing different battery types (brands, old/new, etc.) is not recommended.