I have an upcoming project for Home Assistant which means that I need to be able to measure the temperature in our bedroom. As part of this, I’ve bought a couple of ThermoPro TP357 Bluetooth thermometers from Amazon (sponsored link). One is for our bedroom, and the other is for our eight-year-old’s bedroom which tends to get a bit cold in winter.
I specifically went for these thermometers because they’re:
- Cheap – I paid £19 for the pair last week, but they’re £16 for the pair as I write this.
- Supported by Home Assistant – there’s an official integration.
- No extra hardware required – because they’re Bluetooth, and I run Home Assistant on a Raspberry Pi with a supported Bluetooth chip, there’s no additional hardware required to get the two to talk to each other.
- Probably good battery life – Bluetooth is quite energy efficient when compared with, say, Wifi, and so the batteries should last longer.
- No need to use the cloud – all the data can be stored locally on Home Assistant.
ThermoPro TP357 look and feel
The ThermoPro units are smaller than I expected. They’re about as tall as a credit card but roughly square, so they’re narrower than a credit card. Each one runs on one AAA battery which is provided. On the back is a flip out kick-stand, a magnet and a hook, so you can wall-mount it, stick it to your fridge or have it free-standing on a shelf like I do. There’s also a button on the back that switches it between Fahrenheit and Celsius.
On the front, there’s an LCD screen which shows the current temperature and humidity level. There’s also a face pictogram – it’ll smile when the humidity is between 30-60%, frown when it’s less than 30% or show a neutral expression if it’s over 60%.
Home Assistant integration
If you have Bluetooth enabled on your Home Assistant device, then a few minutes after you put the battery in, Home Assistant should pop up a notification to say it’s discovered a new ThermoPro device. You’ll just need to confirm that you want to set it up and allocate it to an area, and you’re done.
As you would expect, the ThemoPro integration reveals entities for temperature and humidity, but also the battery level. I’m not sure how accurate this is, as both provided AAA batteries just show 50%. I’ve added these to my Home Assistant dashboard, and have set up some additional functionality that I’ll blog about later. Mainly because, despite allegedly being ‘summer’ in the UK right now, it’s not been warm enough for me to test.
The range seems quite good on these. ThermoPro claim that there’s an 80 metre range in direct line of sight. There’s a few thick walls between my Home Assistant device and the thermostats, and one that is around 5 metres away doesn’t have great signal strength but it’s enough.
ThermoPro app
Of course, ThermoPro expect you to use their app for iOS and Android. This includes logging of up to a year’s data, and you can set notifications based on events related to the humidity and temperature. Well, that’s what it says – I haven’t actually installed the app. I’m not yet sure if it’s possible to have the app and Home Assistant communicate with the thermostat at the same time. But theoretically, anything the app can do, Home Assistant can do too.
Alternatives
I’ve had various Facebook adverts for alternatives to these. Some have e-ink displays, which are more readable at a distance, or use different protocols to Bluetooth. But they’re all more expensive. These two seem to do the job well and are small and cheap. Plus, it should be quite a while until I need to replace the batteries.
