I had seen these and everyone who uses these seem to love them but IMHO I think they are pricey as other wired solution are very inexpensive...also I read somewhere that the accuracy is with 2C which is very high. Imagine your thermostat is set to run at 70 degress but it is actually 68 or 72. I am simplifying by using F temp but that is the same problem with the templinc from smarthome. very easy to use greate plugin for HS but the range is toomuch. THe wired solutions are with in 0.5F
I would still buy them as they would serve the purpose of having them anywhere in the house without running wires but like I said...still a little out of my range.
A wired solution is cheaper in some cases. This RF solution can be used where wiring is not possible or gives a lot of work to hide the cable into the wall. When lightning problems are to be expected when running a cable between buildings then the wireless sensor is a better choice. You also have the freedom to stick the sensor on any place you want as long as RF is not blocked.
If you have a W800 or an RFXCOM receiver then you are able to receive the RF signals from the RFXSensor units and there is no other PC interface needed.
Accuracy: The sensors used are DS18B20 and DS2438. Those sensors are also used in wired 1-Wire networks so they have the same accuracy.
Each RFXSensor Type-3 can be set to a specific address between 0 and 256 in steps of 32. So 256/32 = 8 RFXSensor Type-3 units can operate on the same frequency.
Each RFXSensor Type-3 can have maximum 8 1-wire devices (DS2438 or DS1820) connected.
â€¢ A DS18B20 device has 1 temperature sensor only and counts for 1 sensor.
â€¢ The DS2438 device has a temperature sensor and an A/D sensor and a supply voltage sensor.
In total you can have 8 DS2438 devices x 3 sensors = 24 sensors on one RFXSensor Type-3 unit.
Each DS2438 can have a humidity sensor connected.
If you connect 8 DS2438 devices to an RFXSensor Type-3 then you have 8 temperature sensors AND 8 humidity sensors AND 8 supply voltage sensors.
And so 24 sensors x 8 RFXSensor Type-3 units = 192 sensors total on 1 frequency. Or in other words: 64 temperature + 64 humidity + 64 supply voltage sensors on 1 frequency at maximum.
The RF activity of an RFXSensor can be relatively high in comparison to the X10 security devices. When there are temperature or humidity fluctuations then every minute (in fast sampling mode) or every 5 minutes (in slow sampling mode) the unit will transmit an RF packet. The chance on collisions is high then. A maximum of 64 sensors on 1 frequency is OK.
If you use an RFXSensor Type-3 unit on both frequencies you can have:
2x8 DS2438â€™s connected = 2x8 temperature sensor + 2x8 humidity sensor + 2x8 supply voltage sensor
Or 2x1 DS2438 (the fixed mounted) and 2x7 DS18B20 = 2x8 temperature sensor + 2x1 humidity sensor + 2x1 supply voltage sensor
Or 2x1 DS2438 (the fixed mounted) and any mix of 7 additional devices of type DS2438 or DS18B20.
In the future the humidity sensor can be replaced by a barometer pressure sensor or a linear 10K potentiometer. This needs an extension of the ACRF plug-in. The humidity sensor will be supported soon.