Wrong humidity with sensirion

markuster

Hi,

I am using a sensirion sensor with a HomeWork board.

I used it at home and the humidity was about 60%
and then I used near my home and the
humidity was 80%
( I have done this five times and the problem
still continue)


It is very near one point to the other one :
( only 500 feet)

The only diference is that the second place is
a place where there are some electrical
motors working.

Do you know if there is an electronic insulation
problem ?

And How can I solve that ?

Thanks, Mark

Phil Pilgrim (PhiPi)

Mark,

Are you sure your readings are off? It's not uncommon for the RH indoors to be far different from what is is outdoors, or for the RH in one building to be different from that in another. If you can get your hands on a separate hygrometer, you can double check your readings.

-Phil

markuster

Thanks,


I double check using a analog sensor and a digital sensor.

And I still have the same problem.

Do you know if electronic noise could
be the problem.

I was thinking about the power supply.

But I don't know where the problem is.

Do you an idea ?

THanks, Mark

Franklin

Are you using the same power supply for both readings? Also with the analog sensor what are your readings?

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- Stephen

David H.

When you say you have the same problem, do you mean you are getting the same reading?
If so, I don't see a problem. Only that the humidity by the motors are higher. This could by the sun warming the motors, or caused by the added heat from them running. Either way, if you're getting the same reading,... chalk it up as confirming your readings.

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David


There are 10 types of people in this world,...
Those that understand binary numbers, and those that don't!!!

markuster

Thanks,


I am using the same power supply
for the sensirion.

And It is very extrange to have 60% in one place
and 80% in an other place.

Both places are near ( only 500 feet)
and windows are open in both places
, then, it must be the same humidity.


( I have one sensirion , and I walk to the second
place and there is about 80% )

I don't understand why I have
20% of difference between the both places.

Do you know that motors could
be the problem?

It is very extrange becuase the temperature
is OK , but the humidity is not OK.

Thanks, Mark

David H.

I don't know for sure. But I'm thinking that if the motors are running occationally, they produce heat, and maybe added moisture around the motors. This would increase the humidity reading I would think. Depending on how often the motors are operated. If they are never running, I don't think it would make any difference in the humidity.

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David


There are 10 types of people in this world,...
Those that understand binary numbers, and those that don't!!!

Dave-W

Mark,
It is not unheard of to have a 20% change in the same building only 500 feet apart. Just in one area of my basement is 34% and in the other side, seperated by a door it is over 60%. In the other side I have storage of many cardbord boxes storing junk. The cardbord seems to hold the moisture much longer than the low side that is just open area.

The only way to be sure if your sensor is tricked by the motors is to check it with a analog RH gague. Let me know what you find.
Dave W.

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D. A. Wreski

markuster

Dave W. :


I check it with a analog RH gague at both places
and RH is always the same ( About 60% ) .

The sensirion shows 60 % at the first place .
But at the second place shows about 80%

Thanks,

steve_b

Having windows and doors open will equalize Barometric pressure, but you will still get a difference in Humidity and temperature.
If you had more doors and windows open, then you'd probably be closer to equalizing humidity....but a little bit of solar energy can easily change things up....so take it with a grain of salt!

At airports, we've installed equipment at the ends of runways, which happened to be at the end of a peninsula (surrounded by water). What would somtimes happen is fog would roll in and the Rh would be 100% there, but not at the center of the runway (~800ft away)....so some things can be quite localized!

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<FONT>Steve



What's the best thing to do in a lightning storm? "take a one iron out the bag and hold it straight up above your head, even God cant hit a one iron!"
Lee Travino after the second time being hit by lightning!

Phil Pilgrim (PhiPi)

Mark,

When you measured 60% where the Sensirion measured 80%, did you leave the analog sensor sit for several minutes? Analog Rh sensors can be very slow to change, due to the nature of their sensing mechanism and the fact that many are exposed to the atmosphere only via small vent holes. The humidistat in my bathroom that controls the ceiling fan, for example, often doesn't come on until after the shower has been turned off, even though the room has been quite steamy for several minutes.

-Phil