Install Wifi Relay with old Thermostat as backup

Hardware WiFi Relay
1

Hi,
Is it possible install the wifi relay with the old thermostat?
My boiler have a contact as switch. I think then the output of wify relay and old thermonsta connect in parallel mode.

Is right?

Thanks,

2

What do you want the “backup” to do - prevent the boiler from making the water too hot if the WiFi relay fails to open, or make the water hot if the WiFi relay fails to close?

If you want the first, you must connect the two switches in series. If you want the second, then yes, you connect in parallel.

3

Yes, the second case.
The problem is that where I now have the thermostat I do not have the 220V and the Wifi Relay I have to put it outside near the boiler.

Is there a version of the 3 / 5V Wifi relay? The relay output in my case does not absorb current.

Thanks,

4

As far as I know, there is only the one WiFi relay version.

Do the wires to the thermostat not start at the boiler? If they do, you can have the WiFi relay next to the boiler and wire it into the same terminals as the thermostat. If not, I think you will need to install another cable - either to power the WiFi relay or to connect the output to the thermostat.

5

Yes, no problem. I have exactly this setup in my own home. Using WiFi relay to control worcester bosch greenstar 24i boiler with the old thermostat connected in parallel (just in case), although I have never used the old thermostat since!

6

I saw the basic scheme. It seems there is a 9V DC connection.
http://harizanov.com/wiki/wiki-home/three-channel-wifi-relaythermostat-board/img_20150224_09382621/#main.

Is it correct?

7

Correct, the relay is powered by 240V AC. There is an on-board AC-DC converter.