Comet system forum

brianmca · 27-08-2013 23:00:14

We have a T3511 with an external probe, about 1 year old. The humidity sensor appears to falsely jump to 100% and get stuck there. Here's an example (blue line is temp, green is dewpoint):

Here's what another (non-Comet) sensor showed for the same time:

Is the probe damaged ? Defective ? It did not behave like this when we got it.
Note: the deviation in the temperature at 18:00 is due to an inadequate sun shield, as is the bump at 07:00 on the other sensor.

HonzaD · 28-08-2013 07:19:01

Hi brianmca,

You wrote too few information and I am not able say what can be wrong.

But let me guess ... your dew point is very close to condensation. And I think condensation is your problem. When condensation occurs watter vapour from air change state to liquid. And if there is liquid under sensor cover, device shows 100%RH. If you were carefully remove sensor cover in this state you find under sensor cover liquid water. IMPORTANT! If you decide to remove sensor cover, do not touch the sensors. Any touch can damage them.

Jan

brianmca · 28-08-2013 21:59:36

HonzaD wrote:
You wrote too few information and I am not able say what can be wrong.

This is what I have. If you can suggest something specific to look at, please do.

HonzaD wrote:
But let me guess ... your dew point is very close to condensation. And I think condensation is your problem. When condensation occurs watter vapour from air change state to liquid. And if there is liquid under sensor cover, device shows 100%RH. If you were carefully remove sensor cover in this state you find under sensor cover liquid water. IMPORTANT! If you decide to remove sensor cover, do not touch the sensors. Any touch can damage them.

Jan

That something I've considered but can't easily investigate. However, it wasn't doing this when we installed it. Here's a typical day from September 2012:

Why would we be having condensation issues now ?

PetrS · 29-08-2013 07:13:58

There is necessary to provide more information about place of instalation and application (where and how the equipment is used). Place instalation photo welcomed. From your graph it seems to be condensation during night (from 2 AM till morning).

Comet system forum

Temperature, Humdity,

Pressure Transmitters

and Data Loggers

#1 27-08-2013 23:00:14

T3511 humidity sensor problem

#2 28-08-2013 07:19:01

Re: T3511 humidity sensor problem

#3 28-08-2013 21:59:36

Re: T3511 humidity sensor problem

HonzaD wrote:

HonzaD wrote:

#4 29-08-2013 07:13:58

Re: T3511 humidity sensor problem

Board footer