Homey Community Forum

[HOW TO] make a Nest hello doorbell z-wave trigger

Iam trying here to explane how you can make a trigger when someone is pressing your Nest Hello with the use of Z-wave.

What do you need.

Importent thing is make sure your nest is working on 12V not 24V (12vac relais are cheaper and much better availble)

First step. Breakout the (reed contact) of the Neo Coolcam Sensor.

Then solder 2 wires on the the ends.

And make a litte hole in the cover off the sensor so that it can be plased back on top off the Battery.

This one looks terrible i know just a old cover i maked as example.

Now you need the chime wich is deliverd with you nest Hello and you must have installed.


The 2 wires in the red circle must being connected to the 12vac of your relais.Knipseldf

Then you conect the 2 wires from the doorsensor to the NC (normally clossed) contacts of the relais.

If you wanna make it a bit nicer you put all the stuff in a nice box .

And here you go, a perfect working zwave trigger to use in Homey.


  • using also a chime you wil need a relais with double contacts, as you can not use the same for both.
  • In europe you can use the nest hello with 12VAC instead of 24VAC

Very nice idea! Make something great even greater :grin:

Sorry for bumping an old post. But I am going to implement this hack :grin::+1:.

But could you help me with the relais part?

The 12v is connected to pin 1 and 5?
And the coolcam sensor on pin 2 and 4?!


Thanks in advance :+1:

Yes the coil of the relay point 1 and 5 is conected to the chime connector

The doorsensor to point 4 and 2 (NC) or 4 and 3 (NO) depending on what you want.

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It works :+1:

Except for 1 thing.
Connected it to pin 2 and 4. But it seems to work like a switch :thinking:. Press the doorbell sets the state to open and on the second press it’s closed.

Is it me or did I do something wrong?


If installed it correctly that shouldnt be the case. I suggest to check it.

Or share how you connect things and what reley what sensor

Have it fixed. It was probably the distance between te doorsensor and the closest zwave mesh device.

Solved it by setting a longer ring-time. This will keep the relais open for a longer time and that makes it less sensitive for a not optimal connection.

@RoyWissenburg: heb jij ervaring met de url van Nest Hello streamen naar Homey en gebruik maken van Imagegrabber op basis van beweging door de Philips Hue outdoor sensor?

No, and for what i know its even not posible.

Thanks! and sorry for not asking in English :wink:

Is it possible to use an other door sensor brand/type?
Can’t find this one online anymore. Only fake ones at Ali xpres.


And sure you can use anyone you like, as long you can get to the reed contact of the device

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Dear OP,

Thanks for this guide! I feel this post is very under appreciated!

It’s was a quick and easy “hack” to apply!


I have the chime connected to a relay but the power remains on the relay after a press on the doorbell. Is that normal?

nope, shouldn`t be otherwise the “gong” relais would be powerd always. make sure you have connected them chime correctly

I’ve connected everything according to this schema:

And instead of the chime I’ve connected the wires to a esp8266

And in de nest app turned on that you using a chime.

And also just asking … wich type of relais your using. 12 or 24v because the picture shows 12v relais with 24v current. Wich ofcourse isnt correct.

I turned thee switch to on that I’m using a chime.

833H-1A-F-C-24VDC this is the relais I’m using.

Well dont know then…first thing i would do is disconnect the relais and meassure with a meter whats the output of the chime connector, and what its doing when rigging the doorbell.

I did and the 24 v remains after the doorbell is pressed