Simple Contact Closure Device Needed

I need a simple, inexpensive device that can offer a contact closure over either z-wave or WiFi. I want to create a Switch Item in OH2. When I turn the switch on, the remote contact should close (momentarily, actually - I need a button-press, but was going to do that in code).

I have an on-demand water heater with a control panel. It has a button on it that starts hot water flowing through a recirculation loop. It would be great to put an Amazon Dash button or similar next to the shower. Push the button and in about 45 seconds, hot water is waiting at the shower valve.

I have a similar need for getting telemetry from my mailbox, but to read the status of a microswitch mounted to the mailbox door.

Any suggestions would be very appreciated.

I did this with a door/window sensor via magnet. Works pretty well. The magnet is glued to the flap of the mailbox.

How did you get the signal to OH? Via wires? Unfortunately when I had the mail box installed I failed to run any low voltage cabling to it. So now I am looking for a wireless solution.

I have two mailbox sensors in place, both are wireless:

The Fibaro Door Window Sensor via Zwave and
the Xiaomi Door Window Sensor via Xiaomi Wifi Gateway.

Advantage of the Fibaro sensor: you can extend the range between the receiver and the magnet via wires without soldering. All you need is a cheap reed sensor:

Zwave Controller <-> openHAB <-> Receiver <-> Wire <-> Reed contact <-> Magnet <-> Mailbox flap

Advantage of the Xiaomi: about half the size of the Fibaro, but receiver and magnet can not be too far away from each other.

So depending on your mailbox you need to choose the right one :grinning:

Thanks @sihui!! Now all I need is a wireless remote contact closure I can use to turn on my on-demand water heater.

It’s able to switch voltage or provide a volt free contact (be careful about wiring in this case or you will blow up your water heating equipment)

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I will take a look.

Yep - dry contacts only. No ZAP needed from the device itself (the ZAP could be a Very Bad Thing :wink:

Or take a look at the cheap SOnOff products. Wifi connection without needing a gateway to OpenHAB, but you need to solder to get the right firmware on it.

Actually most of them can be flashed with Tasmota over the air now. No need for a programmer or solder.

Yeah, I know, but because of this post I did not mention it so he does not get disappointed :blush:

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I am aware of these devices (and the soldering - not a problem). Do you guys use them?

Thanks for the heads up. I was unaware that the newer firmware from Itead broke the OTA flashing. :frowning: It was so much easier using OTA.

I use some Sonoff Basics to control my Christmas lights. I don’t really have a job for them the rest of the year.

Hum… so I wonder how I can tell if a device has the older firmware if I buy it on ebay. Sounds like buy and pray.

Not a real big deal if you are OK with soldering or using pogo pins. In the worse case scenario, you can’t flash the firmware OTA. You can still do so through the pins.

The big thing you have to worry about when buying off of eBay is getting counterfeit devices which won’t work with Tasmota at all.

Good point @rlkoshak. I will get a new one.

I bought one last year and after opening it up to solder the pins I decided it was the last one. :sunglasses:

It’s okay for low wattage applications but I would never put any high load on it.

I had a Sonoff POW (16A - the Switches only have 10A), which burned as my washing machine (2000W) was in high mode. But that device was on the “we screwed up” list and I got a free replacement from Itead. I replaced it and it works now since. But I agree, if the device is placed in a inflammable environment, you should be extremely cautious.

Other than that, I have now four POWs and they all work fine - and btw: I didn’t solder once, I just stick the pins in the platine and they got contact - after that you can just pull them out again… In my opinion, this is much more easy to handle as getting everything ready for OTA-flashing… :wink:

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I have a few of them around the house.
I have a custom firmware on them. Very simple mqtt client to activate the relay.
I have enabled the OTA update on them but I only used that once when I changed the IP address of my MQTT broker. No problems there.
I mostly use them to control radiator valves to create zone heating room by room.
But I also have two or three to control lights where I couldn’t get a wired control.

Great little devices BUT be careful with the load you put on them and they are NOT CE certified so your home insurance may frown on that.


Actually, as of October 2016, they do have CE Certification, at least for some of their products.

You can find links to other certifications and the CE reports at the bottom of this page.

And at least for the ones I purchased last year they all have the CE logo on the box.

This is probably another good reason to buy new though and avoid eBay.

Don’t be so sure: Mine have both CE and RoHS (I bought my first ones in February 2017 I guess).