favorite and ACCURATE humidity meter?
favorite and ACCURATE humidity meter?
(OP)
For those of you who do work with existing structures, or who collect guitars or cigars, do you have a favorite hygrometer? I would like to have an accurate number on humidity and temperature when I'm in crawlspaces but am having trouble finding a reasonably-priced and accurate monitor.
cheers!
cheers!
Please remember: we're not all guys!






RE: favorite and ACCURATE humidity meter?
Accurate, eh?
The trickiest thing about hygrometers is that they don't stay calibrated for long, and it's worse when they get dirty. Buy one that has a replaceable element (and from suppliers that will recalibrate them for you, or send you calibrated replacement probes), and expect to pay somewhere north of $300.
Or, buy a sling psychrometer if you can find room to swing one in a crawl space.
RE: favorite and ACCURATE humidity meter?
RE: favorite and ACCURATE humidity meter?
And, in fact, what you are really interested in is the MC of the wood, not the ambient humidity in the crawl space. You can feel that, whatever the exact value, and you should advocate for some controlled venting to settle that moisture level down. However, venting a crawl space is a difficult thing to get right, because of the difference in inside and outside temps. and dew points, and because of the wicking-up of moisture from below. Sometimes drawing outside air into the crawl space actually increases the relative humidity, and defeats the purpose. A strong argument can be made for conditioning the crawl space and moisture proofing it so you can control the moisture. But, that costs money too.
RE: favorite and ACCURATE humidity meter?
RE: favorite and ACCURATE humidity meter?
https://www.amazon.com/Cole-Parmer-22014-Psychrome...
It was difficult to find it on the internet. It is basically a sling psychrometer except that it uses a small battery powered fan to move air past the wick on the wet bulb. While other hygrometers are more convenient, I do not trust the calibration being stable over a long time. Without a fan, any hygrometer can take a long time to reach a stable reading.
RE: favorite and ACCURATE humidity meter?
https://www.sensirion.com/en/environmental-sensors...
https://www.digikey.com/product-detail/en/sensirio...
You may need/want to build your own enclosure/case.
The sensor that is built around is used in higher-end weather stations.
RE: favorite and ACCURATE humidity meter?
Please remember: we're not all guys!
RE: favorite and ACCURATE humidity meter?
RE: favorite and ACCURATE humidity meter?
The issue with contamination is that the sensor portion of the typical capacitive sensor used in handheld/logging devices is a tiny, itty bitty little silicon chip, typically with a tiny 0.01-in^2 gore-tex filter patch over it. If even a grain of regular sodium chloride salt lodges against that filter patch, it will act like a saturated salt solution, absorbing moisture from the air that is above its saturation RH, or giving off moisture when the air is below its saturation RH, and in both cases skewing the actual RH of the air that reaches the chip's sensor.
In laboratories where RH control to within a few percent is required, a chilled mirror hygrometer (essentially an automated psychrometer) is usually specified, as it delivers the required accuracy and traceability. If capacitive sensors are used, they will have their sensor element replaced or recalibrated on 6 month to 1 year intervals.