Monitoring Greenhouse Climates without Breaking the Bank
Summary
Among the three or so temperature monitoring solutions we’ve tried, SensorPush has been our go-to solution. It’s the most reliable with good build quality, great battery life, and excellent app. And at around $50 per sensor, it doesn’t break the bank. You can use it with or without a gateway, though we certainly recommend a gateway unless your greenhouse is very close to your house.
That said, its current suite of sensors is limited to one, a temperature and humidity sensor. We’d love to see a variety of sensors on this platform, including one with the option for a temperature probe (water and soil).
AcuRite Access is a workable solution, but we haven’t found the gateway, associated app, or sensors themselves to be as reliable as SensorPush. Also, your sensors will need the gateway in order to view the temperature on your phone.
The Need for Greenhouse Temperature Monitoring
We currently have two climate battery greenhouses at Threefold Farm, our home farm. After constructing our first one, we quickly realized that temperature monitors, even with min/max recording, weren’t great. There was no way to know, short of going out into the greenhouse (or having greenhouse automation), when the structure was in danger of overheating.
This review doesn’t pretend to be comprehensive; it’s here just to relay our multi-year experience in a challenging environment (a hot humid greenhouse) with a few solutions we’ve tried.
Options We’ve Tried - Acurite, SensorPush
The two main options we’ve used are Acurite’s Access platform and SensorPush with their WIFI Gateway.
Acurite
✅ Acurite Advantages - Inexpensive, Range of Sensors, Decent App
Acurite has several advantages to it. Their basic temperature and humidity sensors are inexpensive, in the $15 range, and their outdoor sensor has a probe that can measure soil and liquid temperature. From what I’ve seen, most of their sensors take AA batteries.
The accompanying app is decent, and it does come with Android widgets so you can view temperatures at a glance.
❌ Acurite Disadvantages - Need for Access Gateway, Number of Sensors, Reliability, Identifying New Sensors
Because Acurite chose to use RF (radio frequency) communication for its sensors, there’s no way for your phone or other device to directly “talk to them.” As a result, you need to purchase the Acurite Access gateway (~$130 at the time of publication). Unfortunately there’s a limit of seven sensors with the gateway. However, if we have two sensors per greenhouse (four total) plus one for each of our cooler areas and an outside temperature, we’ve already reached our maximum.
Acurite sensors are inexpensive but we’ve found the basic sensors to have a life of 1-2 years before they become somewhat unreliable or stop working. We’ve had several that have lasted longer than that and I’m honestly not sure why. Still, they’re not rock-solidly dependable, and that’s been an issue. We have fared better with their outdoor temperature monitor with plug-in sensor (00275RM + additional sensors) and those have stood the test of time, but their price puts them in league with SensorPush. The AA batteries used on these sensors are nice, and coupled with lithium batteries would probably provide a decent solution. We use less expensive AA batteries (we have kids) that don’t hold up nearly as well when temperatures drop below freezing.
As a result of using RF, Acurite sensors almost need to be numbered to function properly and added to the gateway. If you power on one or more sensors and the gateway picks them up, it can be difficult to uniquely identify the two until after you set them up and can see the temperature they’re reporting. The plus side of RF is its relatively larger range compared to Bluetooth LE. In practice, it provides slightly more flexibility in terms of sensor placement. If Acurite has addressed this issue, let me know in the comments. I’ve since moved on to SensorPush.
Our Acurite Outdoor Temperature sensor with Soil/Water Probe. This one has been the most reliable but its readings in direct sun seem to be high despite what appears to be some radiation shielding.
SensorPush
✅ SensorPush Advantages - Build Quality, Sensor Features, Accuracy, Battery Life, Solid Gateway, App, No Sensor Limits
After two years with Acurite, in January of 2019 I purchase a couple of SensorPush units, initially as a way to measure inlet and outlet temperatures in the climate battery. At $50 apiece, they were significantly more than Acurite’s basic sensors, but I liked the idea of Bluetooth LE connectivity and the small form factor.
Since then, I’ve purchased three more SensorPush sensors as well as their accompanying Gateway. All have held up and performed well to this day, and none of the sensors have needed a battery change, even after 2 years of constant use. Whether monitoring through a direct connection with my phone or reporting via the gateway, none seem to miss readings. Plus, if they lose connection with the gateway, or it goes down, each sensor can store temperature data for two weeks, ensuring that stored recordings are not lost.
I haven’t seen any issues with the SensorPush gateway. It hasn’t needed a reboot (Acurite seems to need one periodically) and has kept a solid connection with the sensors themselves. It also connects via WIFI with our network, as opposed to the wired connection needed by Acurite.
The SensorPush app is straightforward and simple with nice graphs of temperature data. It would be nice to see daily min/max values on the screen via some customization and perhaps a widget for Android devices, but other than that I have no complaints. It just works.
One last thing: unlike Acurite, SensorPush does not limit you to a maximum number of sensors per gateway. I assume that there is a workable limit at some point, but it’s nice to know I won’t need to add another gateway just due to adding one more sensor.
❌ SensorPush Disadvantages - Odd Battery, Lack of Sensor Options, Limited Range
While the SensorPush sensors have long battery life, they do use a fairly non-standard battery, the CR2477. It is still accessible, and only runs about $3-4 apiece if you buy more than just a single one. Not a deal-breaker. Since I haven’t had to change batteries, I can’t comment on the process, but SensorPush’s newer sensors have an “easy change battery cap”, so I’m guessing that battery changes are at least somewhat of a pain point.
We use the SensorPush model HT1. From browsing their site, they appear to have a couple new options, but no weather station type sensors nor do they have one with a probe attachment. Both would be nice in a farming situation. We’ve used a compost type probe thermometer for one-off readings as a substitute for soil temperature. It’s really not quite as critical to measure soil temperature in the climate battery minute by minute like these sensors record. It’s sufficient to get a general reading once a week or so.
SensorPush sensors use Bluetooth LE for communication. Per their website, this should allow a line-of-sight range of around 300’. In reality, with almost any obstructions, the working range appears to be around 100’. We positioned our gateway halfway between two greenhouses in a covered space inside a weather-resistant enclosure in order to pick up signal from all of our sensors, as it appeared that the metal walls of our building were leading to drops in connection. If you choose to use a gateway-less solution, expect that your phone or other device will need to be in that ~100’ range before it syncs well. In reality, this is pretty similar to RF sensors, though they may have a slight edge here.
Our durable little SensorPush sensor. We number ours as we move some of them through the season to monitor different areas of the farm. This one spends its winter in the greenhouse.
Temperature Accuracy & Radiation Shielding
Both the Acurite and SensorPush sensors benefit from solar radiation shielding. Solar radiation shielding allows higher temperature accuracy when the sensor is in the full sun. If there is no shield, the sensor body itself can heat up, throwing off the temperature readings significantly. The Acurite outdoor monitor, even set up with what looks like a temperature shielding shell, seems to suffer from this. I’ve used the Acurite solar radiation shield for both the Acurite sensors and SensorPush, though there are several on the market, and mount or tie the temperature sensor inside it.
Overall, the SensorPush and Acurite sensors both seem to be reasonably accurate, though I put more stock in the SensorPush readings. The Acurite sensors seem to read a bit high on most sunny days, perhaps due to solar radiation influences. Readings are almost identical at night. (As a side note, I haven’t formally calibrated my sensors).
A radiation shield in one of the greenhouses. This one is big enough that it can house an Acurite sensor alongside a SensorPush sensor. Radiation shields help improve the accuracy of the readings, especially when the sensors are in direct sun.
Pricing (Gateway + 5 Sensors)
Acurite - $245 - Access gateway ($130), 2 higher quality sensors ($35 each) and 3 temperature sticks ($15 each)
SensorPush - $350 - G1 Gateway ($100), 5 HT1 sensors ($50 each)
Other Compelling Options
Temp Stick - $150 each
Temp°Stick is a WIFI enabled option. I can’t speak as to its range, but have heard several other farmers recommend them. They appear to use AA batteries and claim a life of up to 1 year. However, at $150 each, they get expensive rather quickly. A five sensor solution as mentioned above would run $750. As a single sensor solution, it could certainly be economical.
Other Bluetooth LE Sensors - Sensors $15-40, Gateways $50 - Nonexistent
A quick search will show that there are several sensors that seem to be following SensorPush’s path (and actually look quite a lot like the little sensors). We’ve picked up some Inkbird sensors that fall into this category. At first glance they don’t seem to be as solidly built as the SensorPush, and I’ve had initial frustrations with several apps (for some reason they have several apps, and not all work properly with the sensors). Time will tell whether they prove to be an effective solution.
The Inkbird solution has a WIFI gateway while the others rely on the Bluetooth connection to your device to upload their data. In a farming situation, WIFI is almost essential unless you never leave the farm.
Conclusions
While it’s not the absolute cheapest solution, SensorPush meets all of our needs for monitoring our climate battery greenhouses, two coolers we use in the summer, and the outside temperature. The sensors’ reliability, durability in harsher outdoor or greenhouse environments and good battery life all contribute to our “it just works” assessment of the product. We move some of the sensors around as we go through the year, and the app makes it simple to rename them and remember where we put them (since they are rather small). We’ve also had good interactions with SensorPush email support when determining where to place the gateway and its limits.
Please note that we weren’t sponsored by anyone to write this. Our goal is to share an honest assessment of what works on our farm so you can save time and hassle on yours.