Got a remote digital therm/RH - excited...then disappointed

[longash]

First let me say that I love gadgets .

So, I got my first humidor (Cuban Crafters 50 ct.) w/analog hygrometer.

I calibrated the hygrometer with the salt test like the instructions said to and after 2 days it read 79%. So, okay, it's reading 4% points high (if I did the test right). It's analog and I know from reading here that the analog hygrometers aren't accurate.

So, I bought this (remember, I love gadgets)

http://www.amazon.com/Honeywell-TM00...3276086&sr=8-1

I also bought a One Step EZ Hygrometer Calibrating Kit that comes with a ziploc bag and a pre-made salt packet.

Well, I couldn't fit the remote transmitter in the ziploc bag that came with the calibrating kit (it's about the size of a deck of cards) so I put it and the salt packet in a larger sandwich ziploc bag and left it alone for 2 days. I had high hopes because the temp reading was right on (I checked it with my wifes digital cooking therm) and because the hygro was digital.

I'm so bummed, after 2 days in the ziploc bag, the hygro never got above 69% . The calibration kit was set for 75.5% accuracy, so that means that the digital remote is 6-7% low. Worse than the crappy analog that came with my humi! And there's no adjustment on the remote sensor.

I know that I can just do the mental math and if I want 69% RH in the humi, I need to see 63% for the remote signal. However, I like things to be accurate (especially digital) and it bugs me that I can't just look for 69% on the display.

I still like being able to see the inside environment of my humi without having to lift the lid.

Rant over.

[shilala]

You may want to do a regular salt test.
I'll tell you why...
I checked out the little humidity calibration bags. They're tiny. The direction say to leave that little guy in there for 24 to 36 hours. That sucks.
The little bag only has a small amount of water among the salts and it takes a long time for it get through the permeable membrane.
It's engineered to work with the bag it came with, so if you use it in a bigger bag it could take a week for it to do it's job. Add to that it may just have used up all it's available water.

So make sure you do a regular salt test.
Oh yeah, and don't use Iodized salt. Iodized salt has Potassium Iodide in it to provide Iodine and that lowers Iodized salt's RH value. I forget off the top of my head what Iodized salt's RH value is, but plain salt is right around 75.7%.

If you've done this, at least you'll know it ain't the calibration kit that's screwing things up.
Good Luck!!!

[gwc4sc]

I feel your pain. I have now got 4 digi's because of the same anal
Retentiveness. The first was +8 the second was -8 the third -2 and so finally I broke down and spent $40 on a prometheus and it is right on. I put the all in the same tupperware container for 2 days with the salt test and was amazed at how different they were. Like you said I could have just done the math but oh well too late now. LOL.

[ChasDen]

Sorry about your new toy. Not to rub salt in the wound, I love the one I just got so I can imagine your disappointment its that far off.

Chas

[Monroe78]

I thought digital was pre-calibrated?

[Spect]

Keep in mind how much temperature effects RH. I can move my digital only a few feet in the house and get slightly different readings.

[longknocker]

Guys, I bought 7 adjustable digital Hygrosets, some from David at www.heartfeltindustries.com and some from Mark at www.Cigarmony.com . I calibrated each one of them with Boveda calibration packs. Everyone of them is spot on after 1 month. I've tried several different 'Pre-calibrated, non-adjustable digital hygrometers' and every one of them is off 5-10%!!! Do yourselves a favor and only buy adjustable Hygrosets from either of the two vendors listed above! You can choose either the round or rectangular model. I prefer the round since it is more compact. Good luck!!!

[shilala]

Originally Posted by Monroe78

I thought digital was pre-calibrated?

The translation of "precalibrated" is "no one did anything and they really don't care because it's Friday and no one is going to check my work anyways".
I just bought three carefully "factory calibrated" hygrometers and they were off anywhere between 5 and 11%.
That ain't gonna get it.
It's best not to trust "factory calibration" or "pre-calibrated" when it so easy to do a salt test yourself.
Then you're absolutely sure.

[longash]

Originally Posted by shilala

You may want to do a regular salt test.
I'll tell you why...
I checked out the little humidity calibration bags. They're tiny. The direction say to leave that little guy in there for 24 to 36 hours. That sucks.
The little bag only has a small amount of water among the salts and it takes a long time for it get through the permeable membrane.
It's engineered to work with the bag it came with, so if you use it in a bigger bag it could take a week for it to do it's job. Add to that it may just have used up all it's available water.

So make sure you do a regular salt test.
Oh yeah, and don't use Iodized salt. Iodized salt has Potassium Iodide in it to provide Iodine and that lowers Iodized salt's RH value. I forget off the top of my head what Iodized salt's RH value is, but plain salt is right around 75.7%.

If you've done this, at least you'll know it ain't the calibration kit that's screwing things up.
Good Luck!!!

I'll try that. All I've got in the house right now besides regular Iodized salt is Sea Salt. Do you think that will work?

[shilala]

Originally Posted by longash

I'll try that. All I've got in the house right now besides regular Iodized salt is Sea Salt. Do you think that will work?

I'm not sure what the composition of sea salt is. I have some and it doesn't say on the jar.
I can check the rh of the iodized salt for ya. I think it's real close to 75%
Go ahead and start your salt test and I'll let you know. How's that?

[longash]

Originally Posted by shilala

I'm not sure what the composition of sea salt is. I have some and it doesn't say on the jar.
I can check the rh of the iodized salt for ya. I think it's real close to 75%
Go ahead and start your salt test and I'll let you know. How's that?

Sounds good. Thanks.

[longash]

Found this :

http://www.cmhc-schl.gc.ca/en/co/mah...o/momo_002.cfm

Calibrating Your Hygrometer

Ingredients

• 125 ml (about 1/2 cup) table salt
• 50 ml (about 1/4 cup) tap water

Equipment

• hygrometer
• a coffee cup
• a 5-litre clear Ziploc™ bag or a well-sealed pressure cooker

Step 1 — Get to know your hygrometer.
If your hygrometer has a pointer, look for screws or knobs on it that will allow you to move the pointer. If there are none, or if you have an electronic hygrometer, physical adjustment will not be possible, but you can still calibrate.
Step 2 — Prepare the mixture.
Place the tap water and the table salt in the coffee cup and stir for about a minute.
Step 3 — Set up.
Put the coffee cup and your hygrometer inside the plastic bag or pressure cooker, and seal tightly. (Note that salty water can damage your hygrometer if it comes in direct contact with it.) Put the bag or pressure cooker in a draft-free place and out of direct sunlight, where the room temperature is likely to remain even.
Step 4 — Check your RH reading.
After 8 to 12 hours, note your hygrometer’s RH reading. Your hygrometer should read about 75 per cent, the standard. If it does, you do not need to adjust it. If it does not read close to 75 per cent, note the difference between your hygrometer reading and 75 per cent. Go to step 5.
Step 5 — Correct to the standard.
If your hygrometer is adjustable, immediately adjust the reading to 75 per cent. If your hygrometer cannot be adjusted, record the difference you noted in Step 4. In the future, each time you take a reading from your hygrometer, you will need to add or subtract that difference.

I'm trying it now in a tupperware container in my home office.

[shilala]

Originally Posted by longash

Found this :

http://www.cmhc-schl.gc.ca/en/co/mah...o/momo_002.cfm

Calibrating Your Hygrometer

Ingredients

• 125 ml (about 1/2 cup) table salt
• 50 ml (about 1/4 cup) tap water

Equipment

• hygrometer
• a coffee cup
• a 5-litre clear Ziploc™ bag or a well-sealed pressure cooker

Step 1 — Get to know your hygrometer.
If your hygrometer has a pointer, look for screws or knobs on it that will allow you to move the pointer. If there are none, or if you have an electronic hygrometer, physical adjustment will not be possible, but you can still calibrate.
Step 2 — Prepare the mixture.
Place the tap water and the table salt in the coffee cup and stir for about a minute.
Step 3 — Set up.
Put the coffee cup and your hygrometer inside the plastic bag or pressure cooker, and seal tightly. (Note that salty water can damage your hygrometer if it comes in direct contact with it.) Put the bag or pressure cooker in a draft-free place and out of direct sunlight, where the room temperature is likely to remain even.
Step 4 — Check your RH reading.
After 8 to 12 hours, note your hygrometer’s RH reading. Your hygrometer should read about 75 per cent, the standard. If it does, you do not need to adjust it. If it does not read close to 75 per cent, note the difference between your hygrometer reading and 75 per cent. Go to step 5.
Step 5 — Correct to the standard.
If your hygrometer is adjustable, immediately adjust the reading to 75 per cent. If your hygrometer cannot be adjusted, record the difference you noted in Step 4. In the future, each time you take a reading from your hygrometer, you will need to add or subtract that difference.

I'm trying it now in a tupperware container in my home office.

That's kinda a hard way to do it, but it'll do the trick.
Make sure there's enough salt so that it refuses to dissolve. That's VERY important.
Iodized salt is right about 74%. Maybe just a little less, but for all intents and purposes, 74% will be fine.
Let me know how it goes, will ya?
Good Luck!!!

[Shaun Raney]

http://www.mayoclinic.com/health/sea-salt/AN01142

Long story short...rock salt and sea salt are both..well salt.

NaCl...they may contain trace amounts of other stuff, but I wouldn't think it enough to worry.

Shilala may find a better answer though.

[longash]

Okay, I feel better now. Here are the results:

I mixed the salt mixture as stated above in one of my wife's ramekins and put it in a tupperware container with the remote sensor. (see pics). It's been 24 hours and the RH has been either 73% or 74%. Which means I'm only 1-2% low.

Why I think the first calibration didn't work;

1. I had to use a bigger ziploc bag than the one that came with the hygro packet.
2. As stated by Shilala above, I think the hygro packet was too small to do an adequate job in 24-36 hours. (also see #1)

Anyway, see my pics below of the base unit, tupperware container, and salt mixture (notice how the salt is "goopy" and sticks to the spoon).