Thermometer/hygrometer

[eryk2kartman]

Hi All,

Could you recommend some good quality reliable Thermometer/hygrometer unit that will show min and max as well? clock on it would be nice but not essential.

I recently got 3 different ones from Amazon but unfortunately none of them is showing the same reading, so i dont know which one is correct, there is around 2-3 degrees difference in temp and around 8% in hum.
I dont know where i can check correct local temp.

So your advice is much appreciate.

Cheers

 

[Wires_Guy_wires]

I have chinese ebay humidity+temp units for about 2 dollars a piece. Their displays are pretty accurate, maybe a 2% difference. They don't set highs or lows (and would that matter within proximity of the soil? I know for a fact that R-humidity is 100% after watering and drops to +/-20% before the next watering.)

Thermometers, especially analogs, work best. Some of those have highs and lows incorporated in the tubing. But what do you want to measure? The air? The plant itself?
And to what end?

I have two logging deviced that run continuously in the backyard, one is arduino based and built (not coded!) by yours truly. It logs temp., Humidity, time and soil moisture estimate and logs it to an SD card. That one was 40 usd to build.
The other was a logging unit bought on the web, I think its called 'Misol' and it was 45 usd and needs specialized software to run. The arduino did too, but after setting it up initally, I only need to reset the clock and date after it has been powered down. The rest of the time it's just a matter of taking the SD card and putting it in my laptop.

 

[eryk2kartman]

Hey,

I just need something reliable for the green house

 

[Wires_Guy_wires]

I see, then I can recommend things like these:
https://ebay.us/bFjJjG

I order them by the bunch of 5. Then put them in a closed ziplock bag, put them in the fridge for 3 hours. Calculate the average of all 5 and use a marker to write down their offset on them.
They don't log, but you can always take pictures with a timestamp and date with your mobile phone. Or write them down manually.
The battery life is quite insane on these, they last about 1.5 years on a single battery.

Price wise, these were the best I could find. There is a variation between the measurements, but it's usually a pretty small percentage.

Logging systems will cost you at least three times as much. They work as well, but they need (sometimes wonky) software and connectors to work. The downside is that if you want to calculate your average in the greenhouse, you'll need a lot of them. But since their output is usually an excel file, it's easier to process fast and reliable.

 

[eryk2kartman]

Hey,

I have one of them already, i order it as i thought it was much bigger i might do what you suggesting, however i would prefer something a bit bigger with nice big display.

 

[ysrgrathe]

Check out sensorpush, no display but easily connects to your smartphone.

Also google saturated salt calibration.

 

[amatbrewer]

Not sure if it is what you are looking for but I have been using a device by Oregon Scientific in my green house for years. Something similar to this one https://www.oregonscientificstore.c...206-weather-forecast-temperature-station.aspx The outdoor sensor runs for a few years on a single battery, and it has been totally reliable. I can't attest to its accuracy, as I only care about reliability and consistency. Oregon Scientific makes some nice stuff that is quite affordable.

Probably not what you want, but I have also experimented with various home built systems based on a simple microprocessor (Arduino) as well as on inexpensive single board computers (Raspberry Pi). Not for everyone, but they can be very reliable and completely customizable. My current system controls irrigation and heating, and tracks temp, water & heat and I can view it at any time on a simple web page. It also sends me an e-mail when it turns the water/heat on/off. The upgraded version I am working on includes a webcam with night vision (just in case I want to watch my plants sleep).

[Yeah, I know the temps swings are excessive. My spring project is to move the greenhouse/cold box into a spot that does not get so much direct sunlight and add forced ventilation.]

 

[eryk2kartman]

Thanks guys,

All info is very helpful, i will do salt test and maybe check thermometer with ice and see whats the offset.

BTW that Oregon station looks really good, i will research it.

Cheers