Hygrometer - Which is best?

I’m looking to purchase a Hygrometer.

Does anyone know which is the most accurate out there?

I have a Fluke 971. About $150. Specs here

I just may purchase that one Linus.

Utilizing a hygrometer is all new to me. Tell me, what sort of humidity (RH numbers) make you investigate further?

The EPA recommends indoor RH of 30%-50%. I can usually feel it when it’s over 50%. If it’s over 50% I recommend a dehumidifier. During the winter alot of times when I do a mold inspection, I find the humidity in the home is high due to the humidifier being cranked to the max. Mold growing behind couches that are placed over a register and the moist air blowing on a cold exterior wall. If the inside RH is higher than the outside RH I investigate further.

Dave…I have went through about 3 different devices over that last couple of years doing HVAC and building maintenance work. This is the one that I use now and found it to be the best one I have come across. It is perfect for home inspection work and environmental testing like mold and radon. I know what the RH is for mold and I can measure wind speeds for radon testing to make sure I’m not testing in over 30mph winds.


I know a Realtor who said the basement carpet was not wet even though my tester indicated heavy moisture (she rubbed it lightly with her hand).

You want me to have her give you a call??

(When she did that I said, “Geez, I spent 300 bucks for this thing and all I had to do was call you”. She quieted after that.)

The old sling psychrometer is the cheapest and most accurate.

You need distilled water on hand and have to sling it for 2 min.

Sticking it in front of a turned on hvac unit (supply and return) prevents the need for slinging!
You really need two (for differential measurements) so this is cost effective and most effective! No calibration required!

The electronics are questionable and they need time (at least 2 min) to stabilize too.

Next, David I guess you missed my post from days gone past.
If you want the wet bulb temp, look for a damp wash cloth at the house! That’s the wet bulb!

I did an inspection behind the “cleaning lady”, boy what a pain in the butt! Water spots everywhere, dishwasher, laundry, toilets, vanities, foot prints in the dinning area…

even a toothbrush!!!\
I hope it wasn’t the cleaning lady!!!

If you have an “unusable” hygrometer](http://ezinearticles.com/?Prevent-Mold!-Hygrometer-Calibration--Tips-from-a-Bellingham-WA-Home-Inspector&id=602308), requires recalibration, try this it worked for mine.

I mixed the salt slurry in a cup with distilled water and put the cup and hygrometer in a sealed ziploc bag for 8-12 hours, haven’t had any problems since and check against others occasionally.

Don’t store this mixture for reuse, start with fresh ingredients each time, they’re cheap.


Thank you, Gentlemen.

Personally I use Extech 445815.
It is pretty decent humidity meter which I find quite accurate. It has alarm with large display and remote probe. It costs around $45, so it is not the cheapest $9 model, but I am happy with it.
This site has some hygrometer models reviewed and compared.
Jenny :slight_smile:

MO290: Pinless Moisture Psychrometer + IR
8-in-1 Meter with Patented Built-in IR Thermometer. This is the most versatile unit. I do water damage restoration and have used most brands. This gives you the most options in one tool.

You’re welcome Dave.
Which one did you go with? It’s been 7 years since you posted this.
Some folks are obviously morons. Must be anti-gun liberals.

I concur. Good model.
You paid a good price. Happy for you.
Is it NIST certified?

Just purchased 971. $667.00 Canadian, metric money, with NIST Certification.

I also use, and have been for some time, MTP 1368 for home inspection ambient RH and Temp.
Fluke is for IR inspections.

Primo Instruments in Montreal. InterNACHI members get 10% discount. They do bonafide calibration, repairs. Trascal.

What is wrong with you?

11 year old thread?

Let it die.