Author Topic: Looking for suggestions on fan aspiration/humidity issues....  (Read 16649 times)

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Offline sam2004gp

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Looking for suggestions on fan aspiration/humidity issues....
« on: September 05, 2008, 06:30:04 PM »
I have the WMR968 in the radiation solar shield purchased at ambient.  There appears to be no fan aspirated kit designed for the OS hardware and that shield.

Has anyone modified or created a home brew fan aspiration shield for it? 

My temps seem to be accurate, but my humidity readings seem to be unrealistic with other non-tramsmitting sensors placed around my property.  I was thinking that the fan aspiration may provide more accurate results. 

Suggestions?

Here is a pic of what my whole setup looks like right now.




« Last Edit: September 06, 2008, 09:42:27 AM by sam2004gp »
SAM --->>> http://www.mountcrawfordweather.org
OS WMR-968 with a Dedicated PWS Weather Computer running VWS v13.01 p09


jwyman

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Re: Looking for suggestions on fan aspiration.
« Reply #1 on: September 05, 2008, 09:21:45 PM »
SAM,
  Get rid of the THGR968 temp/humidity sensor and get a replacement unit like the THGR268. I think i read that the 268 is being replaced or has been replaced with something else. But whatever you do, do NOT get another 968 unit. I had 3 of them sent to me and the humidity readings were all bad... Get the 268 and never looked back. Works just great....


Jim

Offline sam2004gp

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Re: Looking for suggestions on fan aspiration.
« Reply #2 on: September 05, 2008, 10:29:23 PM »
If you look closely at my first pic, I have one mounted under my bracket.  It is the radio shack version of it ( it serves as my channel 1 device), but I think still the same thing.  Both units read about the same numbers most of the time. 


One of the problems I get in the morning is alot of dew on the OS sensor and it may take about an hour longer for it's readings to catch up to the radio shack model.  In the evening the Radio Shack sensor gets the sun exposure at a low angle and then the numbers are off again.  But I never seem to match up to any other PWSs or my local tv station.

I was hoping to keep the dew from "saturating" the sensor so much, but then I guess my fan would have to run at night or 24 hours.

Is it possible that I am too close to the ground?  The sensors are over just lawn grass, and concrete sidewalk is on the other side of the fence.

Here are the "live" readouts that you can look at to see what I get, I will leave them "active" for a day or so:


SAM --->>> http://www.mountcrawfordweather.org
OS WMR-968 with a Dedicated PWS Weather Computer running VWS v13.01 p09


Offline mackbig

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Re: Looking for suggestions on fan aspiration.
« Reply #3 on: September 05, 2008, 10:36:00 PM »
Jim,
I posted this question yesterday in reply to one of yours at the old place.   I saw your home made FARS.  I assumed you were still using the thgr968, so my question was how did you power the fan, as I only saw one wire coming out.  So now that I know you are using the thgr268 (which is battery operated), it makes more sense.  But same question, what do you use to power the fan.  Did you modify your old solar panel from the thgr968, or use something else.

Andrew


SAM,
  Get rid of the THGR968 temp/humidity sensor and get a replacement unit like the THGR268. I think i read that the 268 is being replaced or has been replaced with something else. But whatever you do, do NOT get another 968 unit. I had 3 of them sent to me and the humidity readings were all bad... Get the 268 and never looked back. Works just great....


Jim

Andrew - Davis VP2+ 6163, serial weatherlink, wireless anemometer, running Weather Display.  Boltek PCI Stormtracker, Astrogenic Nexstorm, Strikestar - UNI, CWOP CW8618, GrLevel3, (Station 2 OS WMR968, VWS 13.01p09), Windows 7-64

Offline mackbig

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Re: Looking for suggestions on fan aspiration.
« Reply #4 on: September 05, 2008, 10:43:15 PM »
Sam,
The radio shack unit is identical to the thgr268.  I have three of them that sync with a basic radioshack thermo/hygro base unit that I got long before my wmr968.  Was pleasantly surprised when I got my OS station and the three additional channels magically started reading...  If you think your os one is toast, you could ditch it, the radio shack one will fit inside the pagoda.  So once you do that it will eliminate your evening heating due to sun exposure.

The only drawback is that you lose one channel once you swap outdoor temp within vws for channel 1, but if it improves the accuracy then its worth it.

Andrew

If you look closely at my first pic, I have one mounted under my bracket.  It is the radio shack version of it ( it serves as my channel 1 device), but I think still the same thing.  Both units read about the same numbers most of the time.
One of the problems I get in the morning is alot of dew on the OS sensor and it may take about an hour longer for it's readings to catch up to the radio shack model.  In the evening the Radio Shack sensor gets the sun exposure at a low angle and then the numbers are off again.  But I never seem to match up to any other PWSs or my local tv station.

Andrew - Davis VP2+ 6163, serial weatherlink, wireless anemometer, running Weather Display.  Boltek PCI Stormtracker, Astrogenic Nexstorm, Strikestar - UNI, CWOP CW8618, GrLevel3, (Station 2 OS WMR968, VWS 13.01p09), Windows 7-64

jwyman

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Re: Looking for suggestions on fan aspiration.
« Reply #5 on: September 05, 2008, 11:47:45 PM »
Mackbig,
  I have a low-voltage 12V line running to my unit powering a fan on the homemade shield..... I think i posted some pics awhile ago....


Jim

Jim,
I posted this question yesterday in reply to one of yours at the old place.   I saw your home made FARS.  I assumed you were still using the thgr968, so my question was how did you power the fan, as I only saw one wire coming out.  So now that I know you are using the thgr268 (which is battery operated), it makes more sense.  But same question, what do you use to power the fan.  Did you modify your old solar panel from the thgr968, or use something else.

Andrew


SAM,
  Get rid of the THGR968 temp/humidity sensor and get a replacement unit like the THGR268. I think i read that the 268 is being replaced or has been replaced with something else. But whatever you do, do NOT get another 968 unit. I had 3 of them sent to me and the humidity readings were all bad... Get the 268 and never looked back. Works just great....


Jim

Offline sam2004gp

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Re: Looking for suggestions on fan aspiration.
« Reply #6 on: September 06, 2008, 08:09:50 AM »
I have three of them that sync with a basic radioshack thermo/hygro base unit that I got long before my wmr968.  Was pleasantly surprised when I got my OS station and the three additional channels magically started reading.......

Yeah, the same thing happened to me.  What an added value that we got.  he he. 
I do however also have a habit of buying other wireless weather measuring devices and always worry that they wil interfere with my OS station.  So far so good.
SAM --->>> http://www.mountcrawfordweather.org
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Offline sam2004gp

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Re: Looking for suggestions on fan aspiration.
« Reply #7 on: September 06, 2008, 08:18:01 AM »
Mackbig,
  I have a low-voltage 12V line running to my unit powering a fan on the homemade shield..... I think i posted some pics awhile ago....


Jim


That's an idea use one of those outdoor lighting transformers to run a fan.  Plus at the same time install some decorative lights for the wife to make her happy.  Maybe I could get a small computer grade 12 volt fan from my local radio shack, and figure out a way to mount into the shield.
SAM --->>> http://www.mountcrawfordweather.org
OS WMR-968 with a Dedicated PWS Weather Computer running VWS v13.01 p09


Offline Anthony

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Re: Looking for suggestions on fan aspiration.
« Reply #8 on: September 06, 2008, 08:28:17 AM »
Sam, You mentioned mounting height. By you pics it looks like your is about 10 to 12 feet above the ground. The recomment mounting height for the temp sensor and rainguage is 6'. The recommended height for the anemometer is 33'.



Thanks,
Anthony
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Offline sam2004gp

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Re: Looking for suggestions on fan aspiration.
« Reply #9 on: September 06, 2008, 09:04:11 AM »
The height of my humidity/temp sensors is about 4 feet.  The rain gauge is mounted at 10 feet.   The anemometer is 12 feet.   
I have a homeowners association I have to deal with as far as height of antennas and flagpoles protruding from ones roof.  I had to go thru "the fire" to get the "permission" to put the 5 foot pole on the side of my storage building. 

As for the humidity/temp sensor I guess I could take my "channel 2 unit" and double stick tape it at a different location for awhile to see what I get.

EDIT: I went outside and double stickied another remote sensor under the hangover of my storage building.  Below are the current (just refresh this page every 3 mins to get the new reading) three numbers I am getting.  Now mind you we are currently getting some rain, so TS Hanna is going to make those numbers on the high side, but at least it proves my point about sun shine influenced numbers.

  <<<<WMR-968 Channel (Null)          <<<<<<These two are the ones mounted on the fence post/shield
  <<<<

The "old" newly mounted sensor (it's not in the garage now)>>>>

The "newest" newly mounted sensor double-sticked on the other end of my fence.  No direct sun exposure at this time  >>>> 

 #-o Now I am really confused about what to believe is accurate.  #-o
« Last Edit: September 06, 2008, 03:56:02 PM by sam2004gp »
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Offline SLOweather

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Re: Looking for suggestions on fan aspiration.
« Reply #10 on: September 06, 2008, 10:07:20 AM »
That's an idea use one of those outdoor lighting transformers to run a fan.  Plus at the same time install some decorative lights for the wife to make her happy.  Maybe I could get a small computer grade 12 volt fan from my local radio shack, and figure out a way to mount into the shield.

Keep in mind that the lighting transformer may be AC, and the fan will need DC. You might be able to get away with a single diode to rectify the AC enough to run the fan. Else, a full wave bridge will work.

Also, just about every fan in a computer is 12 VDC. If you have a donor machine around, the power supply fan will work, as will the smaller CPU fan, and any case fans. At work, I remove the fans before the machines go to the e-waste recycler and keep a box full of them around for stuff like this. I built a FARMS (Fan Aspirated Radiation and Moisture Shield) for my home automation temp and RH sensors out in the greenhouse, using a plastic project box, some screen, and a CPU fan.

Offline sam2004gp

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Re: Looking for suggestions on fan aspiration.
« Reply #11 on: September 06, 2008, 10:14:23 AM »


Keep in mind that the lighting transformer may be AC, and the fan will need DC. You might be able to get away with a single diode to rectify the AC enough to run the fan. Else, a full wave bridge will work.
   

Good advice I forgot all about that.  I use to do alot of "electrical" tinkering in my "better" years.

Quote
Also, just about every fan in a computer is 12 VDC. If you have a donor machine around, the power supply fan will work, as will the smaller CPU fan, and any case fans. ....

My brother in law dumped off his old emachine with a blown cpu/motherboard combo, wanting to save his hard drive and copy the data to DVD for him, until he gets a new one.  Hmm, it's a rainy Saturday with nothing to do.  Time to break out the screwdrivers....
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Offline SLOweather

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Re: Looking for suggestions on fan aspiration/humidity issues....
« Reply #12 on: September 06, 2008, 10:19:41 AM »
Just about any 9-12 VDC wall wart power supply will run one of those fans, too. A 9 Volter will run it a little slower, which will be all right.

Offline killwilly

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Re: Looking for suggestions on fan aspiration/humidity issues....
« Reply #13 on: September 06, 2008, 10:23:36 AM »
I have the WMR968 in the radiation solar shield purchased at ambient.  There appears to be no fan aspirated kit designed for the OS hardware and that shield.

Has anyone modified or created a home brew fan aspiration shield for it? 

My temps seem to be accurate, but my humidity readings seem to be unrealistic with other non-tramsmitting sensors placed around my property.  I was thinking that the fan aspiration may provide more accurate results. 

Suggestions?

Here is a pic of what my whole setup looks like right now.






Do you guys really live in houses like in the pics? Is the external cladding timber or UPVC?
Alan

Offline sam2004gp

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Re: Looking for suggestions on fan aspiration/humidity issues....
« Reply #14 on: September 06, 2008, 10:34:42 AM »

Do you guys really live in houses like in the pics? Is the external cladding timber or UPVC?

Yes, people really do live in these houses.   :-)
The subdivision is only 6 years old, so no trees or gutter cleaning to deal with yet.  This style of housing is typical for the lower end of our middle class.

The exterior cladding is Vinyl or "UPVC" as you put it.   

I am humbly curious to what you live in the UK.
« Last Edit: September 06, 2008, 10:45:56 AM by sam2004gp »
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Offline sam2004gp

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Re: Looking for suggestions on fan aspiration/humidity issues....
« Reply #15 on: September 06, 2008, 03:59:24 PM »
I now have all four sensors outside,  the rain is gone now, and about 50/50 cloudy/sunny.   
^^^^^Scroll up to my previous posts for the sensor readings.


2 sensors mounted side by side read the same in the upper 40's.   1 sensor at one of the yard, and another at the other end, both read mid 60's.



TS Hanna turned out to be a none event for us.   :-|
« Last Edit: September 06, 2008, 04:20:54 PM by sam2004gp »
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Offline sam2004gp

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Re: Looking for suggestions on fan aspiration/humidity issues....
« Reply #16 on: September 06, 2008, 04:32:00 PM »
Now my next experiment,  I just put all four sensors within a few inches of each other, no direct sun. Lets see what this proves, if at least my confusion and frustration.

Here are the displays, I will check in around 5:00pm to give them time to settle.
  <<<<WMR-968 Channel (Null)          <<<<<<These two are the ones mounted on the fence post/shield
  <<<<

Ignore the text labels on these

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Offline sam2004gp

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Re: Looking for suggestions on fan aspiration/humidity issues....
« Reply #17 on: September 06, 2008, 05:04:47 PM »
ok 5:00,  the readings were as follows....

CH 0 is 51
CH 1 is 49
CH 2 is 78
CH 3 is 65

Again all sensors within 5inches of each other.

For my next experiment I am going  to take CH 1,CH 2, and CH 3 and place them in a closed dark closet of the house to see what happens.  I will check back at 6:00 to look at those readings.
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Offline sam2004gp

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Re: Looking for suggestions on fan aspiration/humidity issues....
« Reply #18 on: September 06, 2008, 06:35:48 PM »
All 3 extra sensors are in a dark linen closet, they now read..

CH 1=42
CH 2=56
CH 3=52

Now what test should I try?

CH 1 always is close with CH 0 or the WMR-968 sensor when they are together.  And CH2 and CH3 are always close with each other.

Is it possible I have two bad sensors?  And which two is it  0-1  or 2-3?

To throw another wrench in the works.   A separate hand held digital humidity sensor reads 56.


So should I assume: the OS WMR-968 Sensor is reading low (the +11) issue and Ch 1 is way off accuracy.  Ch 2,CH 3, and 15 year old digital handheld unit are correct?
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Offline sam2004gp

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Re: Looking for suggestions on fan aspiration/humidity issues....
« Reply #19 on: September 06, 2008, 06:54:44 PM »
Now I have added the WMR-968 Internal sensor to the mix..

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Offline George Richardson

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Re: Looking for suggestions on fan aspiration/humidity issues....
« Reply #20 on: September 06, 2008, 07:40:43 PM »
Perhaps you could consider investing in a sling psychrometer. Sometimes good OLD technology isn't as glamorous new stuff but maybe better.
FWIW
George

Offline sam2004gp

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Re: Looking for suggestions on fan aspiration/humidity issues....
« Reply #21 on: September 06, 2008, 10:26:25 PM »
My testing is done for the night.  I have determined that Ch 0 and Ch 1 are both inaccurate.  I have now "switched" the channel Ids on two of the sensors.  I now have an accurate Ch 1 and a inaccurate Ch 3 (which under normal use, I did not care about the humidity reading).  The OS sensor will get a "calibration adjustment" in VWS once I have determined what it is to be.

Now all I have to do is get a fan aspiration setup or increased sensor height to keep the sensor getting nightly dew logged.
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Offline W Thomas

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Re: Looking for suggestions on fan aspiration.
« Reply #22 on: September 07, 2008, 01:22:42 AM »
Sam, You mentioned mounting height. By you pics it looks like your is about 10 to 12 feet above the ground. The recomment mounting height for the temp sensor and rainguage is 6'. The recommended height for the anemometer is 33'.




Anthony,
Sorry to barge in here un announced..but is there any way you could get a picture of the PVC shield you have??
I am still seriously considering that type of design. Aspirating  with a fan should be no problem. I was cleaning the shop and found a couple extra 12v DC models I had forgotten about having !
I'm not sure that the stock 968 humidity sensor would ever be terribly accurate but maybe this approach is bound to help somewhat...


Wayne

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Offline killwilly

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Re: Looking for suggestions on fan aspiration/humidity issues....
« Reply #23 on: September 07, 2008, 03:34:00 AM »
Sam, please accept my apologies if it seemed that I was belittling your home. That was most certainly not my intention.

Your method of construction is very different to ours here in the UK. Our homes are built predominately from brick with concrete or clay tile roofs, and some times natural slate, which is quite expensive. We do have timber frame construction, but even then clay bricks are used on the external elevations.

I spent my entire working life in the construction industry. Whilst methods have changed since I started in 1956, materials have changed very little.

My previous home was a cottage built  in about 1570 from mud and stone known locally as "Cob" with a straw thatched roof. These were common building materials in the sixteenth century.

One area of the UK where clapper-board is still used in construction is rural Suffolk. That is due to planning laws.

I don't know what you guys have to pay for you homes, but here in the UK the price of houses had become almost prohibitive for first time buyers. Over the past couple of years the price of property has fallen significantly. My home for example is a three bedroom, two bathroom single story building (Bungalow), measuring a modest 1200 square feet. The current value for my area would be between 400,000 and 500,000 Us dollars.

I hope this explains the reason for my original post.

Alan.
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Offline Anthony

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Re: Looking for suggestions on fan aspiration/humidity issues....
« Reply #24 on: September 07, 2008, 08:27:53 AM »
Sam, No problem getting you a few pics. Just give me a couple of days. If I'm not mistaken. The guy who built it also sent me the instructions, I think. Just hope I can find them on the computer.



Thanks,
Anthony
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