HoneyWell Evohome 2 additional features - Outside Temperature & direct access


So moderately happy user of the Honeywell Evohome connected to Home Assistant setup here. The thing bothers me most, besides the fact that the operation mode doesn’t show already a open issue, is that the outside temp is not something I can get out of the component. It shows on the physical thermostat but not in Home Assistant.

The functionality of the component seems based on the webaccess, this is far from perfect and is very error sensitive. I regularly get email from honeywell that the requested change has not been executed successfully. Something that doesn’t always mean that it hasn’t.

In short:

  1. OutSide Temp available as valuetemplate
  2. Direct control of the thermostat instead of through the cloud

Would love this. :smiley:


I agree, the Evohome component needs some love and some features :grin:

I’m not sure the outside temperature is one of them… afaik the temperature is not from an external sensor but from some weather service. HA can already directly grab that from many services like Dark Sky, weather underground, Yahoo weather, I see no reason to have the same data thru Honeywell services.

For Direct Control, it would be very nice but I don’t think it is possible. Honeywell exposes an API only for their webservice, and afaik the communication between the thermostat and the honeywell server is not documented and (hopefully) encrypted.

Direct Control is a long shot i reckon.

Outside temperature though is something real. I have an outside sensor to help estimate the modulation needed for most efficient heating. The temperature is shown on the physical unit of the Honeywell Evohome. So I hope…

Ok, I did some research… it seems that older Evohome had the option for external temperature sensing but first the sensor was discontinued, then they removed the config option on the Evohome Wifi. As my experience is only with the new release, I didn’t know the existance of such an option.
(my source:

It seems that the API is capable of reporting the outside temperature, so it definitely can be shown in HA.{deviceId}-0

It depends on whether the Heating Unit has an outside sensor. Mine does pre-EvoHome era it worked on outside temperature alone. Wildly inefficient by the way.

So the Heating Unit in my case a Remeha has a sensor unit on the roof and it sends the data to the EvoHome unit. I guess this only works when you have the modulating version of the EvoHome. Like in my case. That’s why it shows up in the physical unit.

I’ll see if I can figure out what value template to use for this sensor value.

FWIW, I use a weather compensator that is attached directly to the boiler, and the evohome system just does call for heat.

Direct control of an evohome system is possible using a Honeywell HGI80 (or equivalent) - there is currently a solution for this using other home automation systems (e.g. Domotitcz). This feature has been posted here as well:

I am pretty certain that the weather is inaccessible via v2 of the api. IIRC, it may be accessible via the older v1 api - there definiteive answer would be in this thread (this is where evohomeclient was created).

This raises an interesting idea - I am thinking of creating a custom component that uses v1 and v2 of teh evohomeclient api to get the best of both worlds…

IIRC the evohome uses a third party for the weather (I can’t recall which one) - there is nothing to stop you/me from accessing the same api.