Sonoff Basic with Single C/O Switch

PureIsle

I have used Sonoff switches flashed with Tasmota firmware to control my underfloor heating ...... switching loops, pumps and boiler.

I have a need for similar to Sonoff Basic but with a change-over switch.

I have not found a Sonoff single switch with c/o contacts. Maybe I missed it? If so please let me know.

Alternatively, please suggest a different manufacturer's product that can be flashed with Tasmota firmware.

My only other alternatives are to either physically hack a Sonoff Basic or to source and add an external housed relay with the desired contacts.

In case my description is not clear ....... I am looking for a device similar to this 4 channel one but with only one channel (switch)

reklamos

I think you could potentially achieve change over with sonoff dual switch(dualr2). I do not know what is your current automation setup but you could automate change over easily.

2011

All you need to do is use the Sonoff you have and get it to drive a relay which has both normally open and normally closed connections.

PureIsle

https://www.boards.ie/discussion/comment/118132809#Comment_118132809

Yes I mentioned that as an option.

Max would be less than 10A 230V

Do you have a suggestion for such a relay in a housing?

Thanks.

PureIsle

https://www.boards.ie/discussion/comment/118132044#Comment_118132044

I only wish to be able to change the output (common) from one of two other input connections - both 230V ac.

I am not certain, from the info I have read, how the dualr2 is to be use .... anything I read referred to light switching without showing any electrical diagram.

Do you have a link to anything more enlightening that would help me adapt it to my use?

Thanks.

2011

https://www.boards.ie/discussion/comment/118133732#Comment_118133732

Yes, I now see you did suggest exactly that, my bad! I'm not sure how I missed that!

Anyway, to be sure you need to start by working out what the load is. Assuming the underfloor heating isn't electric underfloor heating a relay rated for 10A should be fine. In the past I have often used Omron relays for this sort of application.

Why do you need change over contacts? How exactly do you want this to work?

reklamos

Please share what is your end goal with change over.

I have used omron magnetic relays in the past and had nothing but trouble. All is ok initially but they did not last for me.

Sonoff dualr2 is simply 2 basic switches in one housing. Yuo can have multiple configurations(both on, both off, one on and other off). It can be flashed with tasmota. I assume you use some kind of automation(HA or node-red). So in there you could configure that both switches should not be on or off at the same time.

2011

https://www.boards.ie/discussion/comment/118134307#Comment_118134307

I'm not really sure what you mean by "magnetic" relays. All relays were electromagnetic (therefore nagnetic) unless you are considering transistor / semiconductor types but most people wouldn't consider these relays.

From what I have seen Omron relays are widley used in industry due to thier reliability. I have used them for many years in both the pharmaceutical and power generation industries without any issues. However, there can be issues when relays are not specified properly. This can happen when switching inductive loads or motors (as these have a large starting current which can be multiples of the full load current) or even with a resistive load that exceeds the maximum current rating of the device. There are lots of alternatives of course, including ABB, Schneider Electric, Phoenix Contact.

Anyway, as you said it is important to establish what it is the OP wants to achieve.

PureIsle

The pump for the heating can be powered by either of two sources, which needs to be selectable by a change-over switch, the common connection going to the pump and the other two contacts N.O. and N.C. connected to the sources of the 230V ac.

No I do not use any automation such as HA or Node-Red etc.

It is a set up of my own making specifically to suit me and uses a tablet running TasmotaRemota to control Sonoff switches flashed with Tasmota firmware.

It seems my best bet is to use an external relay from one switch to do the selection of source. I probably have a few suitable relays in a box somewhere, but I wanted to use something with a 'consumer' case and the connections well hidden from prying fingers.

I will search here to find a suitable relay and then try to source a box for it.

I had hope to find a Sonoff switch like their Basic but with three isolated connections for the switch.

PureIsle

https://www.boards.ie/discussion/comment/118134307#Comment_118134307

The dualr2 with the outputs shorted together going to the pump and the two sources going to their inputs, set so that both cannot be active at the same time might do what is required.

BUT ...... based on a pic of the diagram on the case, it appears that there are not two completely separate switches ...... 4 unconnected contacts.

Am I reading that correctly?

reklamos

https://www.boards.ie/discussion/comment/118136138#Comment_118136138

As you can see there are 2 relays inside Dualr2. There is a single switch on the device but it has multiple functions. Press once it switches first output, press twice it switches the second. On Tasmota side it looks like this

PureIsle

@reklamos

Thanks, that confirms what I thought ..... there is the possibility of having only one input which is switched to either or both the outputs.

Unfortunately as I posted I required two inputs, switched to the one output, and as that input is used to power the board I cannot switch it off.

###

I think I have a solution. It needs a small bit of rewiring of the system and some alterations to a Sonoff Basic.

I am in the process of hacking the Sonoff Basic to separate the switch contact from the input Live.

This requires removing the Relay & fuse (?), cutting a couple of heavy tracks, drilling a new hole for the fuse and cutting a slot in the board for re-routing the N output wire.

I can then use the relay as a simple switch with two contacts, so I can switch whatever I like, not just the input mains Live.

Thanks for the assist people, appreciate the suggestions.

Hopefully my hack will do what I need. 😓 😉

EDIT:

Hahahaha .... wouldn't ye know it, as soon as I had hacked my switch I found a youtube video showing how it should be done!

For anyone interested here is the video

https://www.youtube.com/watch?v=ywtjnx8cNGU

PureIsle

Hacked switch fitted and rewiring done ........ all good.