DIY Thermostat

Configuration
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1

Hi guys.

I want to DIY my own thermostat to fire my combi boiler on and off (UK).

My boiler needs a dry contact signal to power it on.
I’m thinking of using the Sonoff RE5V1C for this purpose.
I want to install a Sonoff TH10 upstairs that monitors the temperature and turns the Sonoff RE5V1C on or off.

Im completely new to all this.
Can my idea can work?
Is there an easier, better or cheaper way of doing this?
I would be grateful if somebody could point me in the right direction.

Kind regards

CF

2

Yes that hardware will work with this:

3

Thanks buddy
Is there a relay switch that will work using mains input?
The problem with the Sonoff RE5 is that i need to source a 5vdc source.

4

There are thousands.

Sonoff basic, Shelly 1 etc…

5

Yes but those switches don’t produce a dry contact output

6

The Shelly 1 does.

7

Aah brilliant.
I didn’t know Shelly 1 could do that.

When the WiFi switch is turned on… I need the switch to remain on to the boiler to keep it fired up.
Do you know if the shelly does this or is it just a momentary activation of the switch?

Also, in the interest of keeping everything on one platform do you know any Sonoff products that can turn on a dry contact relay (without modifications or with minimal mods)?

8

Yes the Shelly switch is latching.

If you search for “Sonoff basic dry contact modification” on the internet you should get many helpful results.

9

Thanks buddy
I think I’ll opt for the shelly 1 relay.
Do you recommend the sonoff th10 to monitor temperature or the shelly equivalent?
Is there a third option?
Is it just a case of linking the two together using home assistant or eg iftt?

Can I have full voice control of the thermostat using Google?

10

I use ESPHome on an ESP32 board with an SHT31D. As I have no experience with the options you mentioned I can’t recommend either.

Yes just Home Assistant. No need for iftt. See the link in my first post.

No idea. I don’t use voice assistants. They are fancy remote controls not home automation. If you automate your climate control correctly you should not need to send it voice commands.

11

Understood.
Thanks buddy.
To be fair the only automation I want is for the temperature sensing switch to turn on the smart relay to the boiler.
I like to tinker the temperature half a degree here and there.