Topic: Temp and humidity differences with THGR968 and THGN123N

[MatthewWeaver]

I have a OS WMR-968 with stock THGR968 and a new THGN123N.  Installation is similar and software is Virtual Weather Station.  Readings at present:

Device

Temp

Humidity

THGR968

2.48F

56%

THGN123N

1.6F

36%

I'm not sure which device, if either is right.  The coincidence of nearby stations that match one or the other doesn't help.

Any suggestions on temp and humidity differences for THGR968 and THGN123N?

Thanks,
Matthew

[SlowModem]

I have a OS WMR-968 with stock THGR968 and a new THGN123N.  Installation is similar and software is Virtual Weather Station.  Readings at present:

Device

Temp

Humidity

THGR968

2.48F

56%

THGN123N

1.6F

36%

I'm not sure which device, if either is right.  The coincidence of nearby stations that match one or the other doesn't help.

Any suggestions on temp and humidity differences for THGR968 and THGN123N?

Thanks,
Matthew

Take your inside sensor outside and see what it says.

[MatthewWeaver]

Okay, got the indoor sensor outside now.  How long should I anticipate the humidity taking to settle?  The temp is almost there (from 70F down to 7.5F in less than 10 minutes and the outside temps are now at 1.94F and 1.2F).

Thanks!

[SlowModem]

I'd say 30 minutes to an hour should be ok.  hopefully it will match one of the other two.

[mackbig]

Matthew,
At first guess one would say your thgr968 is wrong (many users have complained and or tossed their 968 stock thgr due to bad humidity readings...)

But....
I can guarantee that the THGN123N humidity is wrong without any further information.
Actually I checked my old data from when I was running my thgr968 as outdoor, and I will say that your thgr968 is "currently" displaying the wrong humidity.

One big problem with the sensors from the 968 (and shack equivalents) is that humidty stops reporting at -10 celsius.  So if your current temp is around 2 F you are around -16 celsius.

The humidity that both are displaying is the humidity level they recorded when the temperature passed below -10 C

So they will display 56% and 36% until the termperature hits 14F

Andrew

[Downlinerz2]

Andrew,
   Thank you for that information .  I never heard that before in all the threads about that prob.  I know or think I remember hearing that they also only go to 98%.  Is there a temp cutoff there as well?  I can't find my manuals.

[mackbig]

Mark,
No temp cutoff that I have noticed, the sensors are pretty good for temp (at least in my climate).  Accurate down to my coldest temp of -22C 'ish at least.  But the humidity bug (not in the manuals) totally ruins your dewpoints....

Andrew

[MatthewWeaver]

Mark, I’ve given the sensors over two hours.  The three sensors have settled into their own respective humidity values.  Anthony, you’ve obviously answered the question why and now that you’ve explained it, I realize the values have been remarkably constant.  Thank you both (and everyone) for your feedback.

The original indoor sensor is at 21%, the new THGN123N is at 36%, and the original THGR968 is 56%. (And this likely also tells me who might be using similar OS temperature sensors in the area at this low temp.)

The temperature outside is 0.32F for the indoor BTHR968 sensor and the new THGN123N.  The THGR968 is reading 1.22.

Okay, so, if I understand correctly, the humidity will default to the current values for each sensor when the temperature drops below 14F.  This means my dew point calculations will be invalid.

Now, as regards the temperature.  All three have lithium batteries, the THGR968 likely the oldest and the THGN123N the newest.  With two of three matching, it appears the original THGR968 is 0.72F high.

I currently live in Malone, NY, just south of the Canadian border between Montreal and Lake Placid.  The general area has records to around -60F and I’ve recorded near -30F myself in recent years with the THGR968.  I'm guessing that we'll see well below -30F this winter.

The new THGN123N says spec supports to -40F and while the OS and RS manuals say -4F for the THGR968, it is often advertised to support to-58F.  I’ve read some discussion about whether this -58F value was a typo or not.  (The manual talks about lithium batteries working to -58F so that might be the source of that figure.)  Maybe the batteries become the limiting factor more so than the sensor?

I’m happy with the WMR968 and don’t have the budget for anything more serious at the moment.  In the process of switching from FreeWX-WI 1.02 beta to Virtual Weather Station v14 (p103).  I just bought the THGN123N because it was an inexpensive add-on that might give more range on cold days (and I was concerned over errors I was getting, though I have to admit I hadn’t read enough to realize the problem was because of humidity at the low temp).

Aside from the apparent 0.72F discrepancy by the THGR968, I don’t have any observed problem (and I don’t know the impact of battery age, nor if the amount of discrepancy varies at colder or warmer temps), or, for that matter, if maybe the other two sensors or even all three are in error.
Anyway, would anyone care to share an opinion about whether the THGN123N is value-added or unnecessary?  

[SlowModem]

I’m happy with the WMR968 and don’t have the budget for anything more serious at the moment.  In the process of switching from FreeWX-WI 1.02 beta to Virtual Weather Station v14 (p103).
Aside from the apparent 0.72F discrepancy by the THGR968, I don’t have any observed problem (and I don’t know the impact of battery age, nor if the amount of discrepancy varies at colder or warmer temps), or, for that matter, if maybe the other two sensors or even all three are in error.

The RH in my THGR968 died early on.  I now use the THGR122N.  The range is shorter, but it is much more accurate.  I can't comment on the 123.

I started out with the FreeWX-WI.  I really liked it and would still be using it if I could substitute channel 1 (which is where the 122 is received by the console).

Glad to have you with us.  I was in your area once back in the last century when I was driving a truck.  I had a delivery to Massena, NY.  And my wife was at Fort Drum for a while.

Good luck with your sensors. 

[mackbig]

Matthew,
If your temps go that low its probably good that you grabbed the 123 cold weather version.  I got one of those last year.  But honestly I never had issues with the thgr268 or radio shack  63-1031 (same exact sensor, just different label), low last january of -25.5C (-14F).  I have used lithium and alkaline batteries. Moslty alkaline, the alkaline lasted near 2 years so I dont think at my temps it really is advantages give the price difference. 

I think the spec's they display for OS products is nothing more than an eye ball sometimes.  But I have said before my os station owes me nothing, 4 years in service and still kicking along.  Its too bad they did not fix or disclose this -10C humidty issue though. 

Andrew

[MatthewWeaver]

Final question, is there a workaround or solution to low temperature humidity when using the WMR968?  Either with existing hardware, the THGN123N or another sensor?

Thanks!