Hello,
I’m would like to install some temperature and humidity sensors in my house (temperature and humidity control in a house unoccupied for the winter). I have laid utp cables in rooms in the house and would like to use them.
Could anyone know reliable cheap sensor and way to connect multiple (for example 10) sensors usung existing UTP cables?
Avctually I have RPI 4 and Home Assistant Operating System.
ESP32 with Ethernet port is the only thing I can think of.
Not sure if this qualifies as cheap though since it’s probably more expensive than a battery operated wireless version is.
Maybe use the GPIO ports. Connect sensors via wires from UTP cables to some multiplexer that will collect the values from the sersors one by one and send it to RPI GPIO synchronously?
Type: raspberry pi temperature humidity sensor, into Google.
I think you are making it way too complicated.
How big is the house? You say it’s unoccupied on winter, so I assume it’s a smaller house?
Perhaps one or two sensors is enough to get a decent reading?
What is the value used for? Frost protection? I doubt you really need more than one or two sensors then.
You could do it with 433mhz weather sensors reporting to one or two say OpenMqttGateway esp32 bridge. I have one of these sensors outside running on 2 AA batteries for > 1 year. Works through walls. But inside where I have electrical power points I use esp32 or esp8266 with bmp280 and bme280 on esphome or tasmota. I think sensors will suffer on long wires.
I use the sonoff TH16 flashed with Tasmota. They use wifi rather than Ethernet. I have had no issues with them. They are using AC so no issues with batteries. There are a lot of Bluetooth sensors that are cheap, but most run on batteries.
I started of with a pair of them. Do you have the one with humidity? Mine just did temp. In the end they looked bit bulky. Lead about 3 feet long and was difficult to place.
I have the one with humidity. It is in the attic and crawlspace so cable is not an issue. For small sensors I am using Bluetooth. Batteries seem to last almost a year in side.
The most common is the DHT22 (11). But I heard that they have problems with humidity, hence I’m asking the more experienced abour a more reliable sensor than the most popular one.
Hellis81
It’s a small house, but I would like to have at least four sensors: attic, second floor, second floor, boiler room (without recuperation) and garage (under the uninsulated terrace). I would like to use cables already installed, and buy cheap sensors. I think that building such a measurement system is not a big exaggeration.
@Spiro, bschatzow
I have cables laid all over the house (I assembled them myself;)) and would like to take advantage of that - no batteries, reliable connection ect.
What do you think about SHT30 connected to RPI via I2C. How to do it with multiple devices (multiplexer)? Maybe this is the wrong way (I would like to expand the system in the future), it would be better to use ENC28J60 and use switch?
In my basement I plan to use ESP32 Ethernet/Poe with DHT21 and ESPHome integration. Costly 
Try here Long wires to sensors. Could be a good learning experience. Post back to tell us how it went.