Herschel's Thermostats (except for the T-BT which doesn't have wifi) work via the Smart Life App with Alexa and Google Home via voice command and via a very simple management widget in Alexa and Google Home Devices control panels. Commands in Alexa and Google Home are limited to temperature up & down commands and thermostat On / OFF commands.
Discovery of Herschel thermostats by Alexa and Google Home is automatic, once the two services are correctly linked to your Smart Life App following the instructions below. It is not possible to manage your Herschel thermostats via Alexa or Google Home without the Smart Life App. Discovery occurs in the cloud, not on your home network and also means you can manage your devices via Alexa or Google Home when you are not on your home network.
For Alexa and Google Home control, you do not need a local Alexa or Google device (e.g. like an Echo Dot or Google Home Hub) to run the commands for you: you just need the app. However you will need to enable voice control from the Alexa App and you will need Google Assistant for Google Home to run the voice commands.
How to pair
In Alexa, select "More" and then "Skills and Games".
Type "Smart Life" into the search bar, selet Smart Life from the list and then "Launch" Smart Life. Select The App and a local Home device (like an Echo Dot) and launch. When prompted also selet the ability to control Alexa by your voice on the App.
In Google Home, Select "Add a device" and then "Works with Google Home" and select Smart Life from the list. Once you select it, you will have to authenticate Smart Life with your Google account. Note in order to control Google Home on your App using voice commands, you will also need to install Google Assistant and the two will then interoperate. For Alexa, make sure you enable voice commands on the Alexa app.
Back in Smart life, find the "Me" option (bottom right hand icon) and then select Alexa or Google in "Third-Party Services" as shown below.
When you click into either Google Home or Alexa, you will see a screen similar to the following (different title if it is Google Home rather than Alexa, but same icons below).
You should check your "Synch Management" settings. This is important, since every "Home" you have defined in Smart Life will try to synch with Alexa and Google Home. So this feature cuts down the number of "Homes" (e.g. your office; your home etc) that will replicate to Google and Alexa. If you do not check these permissions, it is possible none of your devices may synch (i.e. all Homes are "OFF") or all of them will (all Homes are "ON").
"Device Control" if you click it, will also be initially ordered by "Home" but if you then drill down to the individual Smart Life devices in each Home, you will be able to see the supported functions in Alexa or Google Home.
Re-Link is another feature worth highlighting at this point as being useful if you need to re-link and re-authenticate at a later stage for whatever reason.
Once linked you will be able to control your thermostats with basic temperature increase and decrease commands as well as thermostat "ON" and "OFF" commands.
Troubleshooting
Alexa and Google Home do not work with Herschel Thermostats independently of Smart Life. Thermostats must be paired successfully with Smart Life and all normal local wifi conditions (good 2.4GHz wifi signal; router doesn't have too many simultaneous wifi connections) must also prevail to also be able to manage the thermostats in Alexa or Google Home.
Make sure Alexa or Google Home have been properly connected and authenticated with Smart Life using the steps above.
Just occasionally, if you have added a device and it is not showing up on Google Home (we haven't yet seen this with Alexa), then force-close the Google Home app and reboot your phone.
Very rarely it is possible a firmware update may be available for your thermostat and it is possible this may block 3rd party features until it is applied, but if you set devices to auto-update (in each device, select Settings (pencil icon to the right of the device name) => Device Update (right at the bottom of the next screen) then toggle Auto Upgrade ON, then this should never be a problem.
Very rarely too, one of Smart Life, Amazon or Google Home cloud servers can run slowly and service may occasionally degrade, but this is only ever temporary.