Internal contacts on ecolink door sensor (DWZWAVE2.5-ECO)

Hello all,

I’m tying to create a project and create a septic alarm zwave trigger. There is a really good article on it that I read but have a few questions.

1.) if I wire the sensor to the septic alarm using the sensor’s internal contacts (believe called dry contacts) and the alarm gets triggered (receives a 12v signal from the float switch in tank) will the device trigger?

2.) how much voltage will the device handle (need it to be 12vDC)?

3.) how do those contacts actually work. I assume one is + and the other is - and when I receives some sort of voltage it triggers it?



Also, I’m having a brain fart… best way to wire it up…

On the alarm panel there are 2 low voltage therminals (+ & -). The foot switch is hooked up to those terminals. I believe (I’ll have to test with meter) that the alarm panel sends 12v through the + terminal and when the float is down (no problems) it creates an open in the circuit. When the float “floats” at closes a contact in the float and completes circuit and sets off alarm.

If I wire the sensor right to the terminals on the alarm panel (+ to + and - to -) wouldn’t that just complete a circuit on the sensor side and trigger the zwave sensor? Or Would I wire the sensor in parallel to the float’s negative wire going to panel. Doing that would create 0 volts at the sensor until the float “floats”, complete the circuit, and send 12vokts back to panel.

Maybe I’m thinking about this all wrong. I could open the panel and tie the sensor into the actual alarm buzzer but I think that buzzer is 120vAC so I’d have to step it down.

So the EcoLink external contacts are a “dry” contact. They arn’t meant to handle any voltage. Sending them 12v will probably kill your sensors.

You need to provide a dry set of contacts. If you don’t have any you can convert your 12v output to dry contacts with something like a RIBU1C relay. It will take your 12v signal and covert it into a dry contact which can be used by the EcoLink.


The ecolink sensors are meant to be used to sense a short or open. A short means it is closed open means open.

I use these sensors in my wired alarm box. I have the various wired zones attached to the ecolink sensors. If you have a float valve that simply open and closes a switch you could tie one of these sensors to it.

Vseven… I’m confused here… if it’s not meant to handle any voltage, how does the dry contact know if it’s “open” or “closed”. I guess I’m confused because the sensor dry contacts are meant to have small gauge wire attached to them. What kind of “signal” travels through the wire that doesn’t have any kind of voltage or current?

Terminal… that’s exactly what I want to do, but how do I hook it up? In series with one of the wires coming from alarm box (say positive wire going to float)?

Most things that are dry contacts are sending a tiny signal themselves and are looking for it on the other side. I.e. they are looking for the two contacts to close together. So if you put a paperclip between the two it would read closed because one side is sending the signal and the other side is looking for it. This is also why you can’t use these types of sensors (or leak sensors) to detect things the opposite way…that tiny signal when connected permanently kills the battery but when not connected its fine.

If you have a dry contact, i.e. a float that when raises just closes contacts with no voltage involved then that will work fine. But if whatever you are using produces voltage when it closes, like the 12v you mentioned, it would fry the sensor. \

Are you trying to maintain it as part of your alarm panel also? If so you can add a relay and maintain that connection and also use it for SmartThings. If you don’t want to maintain the connection then pull the alarm system off of it and it should be a dry contact.


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I get it now. So since the float is 12v, I could use just an automotive relay. When the float closes the circuit it will energize the relay.

I would want to see a actual wiring diagram to understand better but my guess is yes, you can use a 12v relay like the one I listed or like those for car wiring (as long as the 12v doesn’t pass through) to close the EcoLink contacts and still maintain the connection to the security system (should be able to).

If the float energizes the automotive relay then you could take the common and a NO(Normally Open) contact and attach them to the two Ecolink connections. It doesn’t matter which one you connect to where. You are just shorting and the ecolink inputs with the relay contacts Just don’t connect any powered input to the ecolink. How you power up the relay is another matter.

Got it… thanks. I’ll try the automotive relay trick. The 12v from from the float should energize the relay and the other two terminals that the relay will open will be hooked up to the sensor. Easy enough. I’ll be heading up to the cabin this Thursday and will do this then. I’ll let you know how it goes.

I just ordered this:

It seems it will look cleaner than just an automotive relay dangling around.

I’m assuming this would work? The relay energizes at 12v which is what the float switch sends when it’s activated. I’d then hook the dry contact switch to the NO terminals on the relay correct?

The reason I like the RIB’s is they are all enclosed and made to mount on the side of a junction box so you can see the light when they are activated but don’t have any exposed wires. But what you bought should work fine.

I didn’t see your recommendation on the relay before. I like it, so I ordered that one instead!

Thank You!

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Lay question, I swear…

Attached is a drawing and the wiring scamatic of the relay.

Basically cut the black (neg) wire and wire put the relay inline with it? Black wire from float gets attached to relay’s wht/blu wire then relay’s wht/yell wire gets attached back to the float’s black wire going to panel? Then wire the sensor’s dry contacts to the relay’s common (yellow) and the Normally Open (org) wire?


This is awesome. So many possibilities doing this. I’m sure I could even set something up with my smoke alarms as they are inter-connected using this same setup. It would save money over buying zwave smoke alarms.

Yeah, that should work. And yes, thats how I would wire it also.

As for the smoke, if you have Kidde sensors: Integrating Kidde Smoke / CO Sensors into SmartThings Properly .

And if you really want to be able to pull a whole bunch of stuff into your system relatively cheap: [RELEASE] ST_Anything v2.9 - Arduino/ESP8266/ESP32 to ST via ThingShield, Ethernet, or WiFi

There is a lot you can do if you are willing to play with it.

Ok… so I wired it up as described and tested it. It did trip the smartthings sensor which is awesome. The light on the relay also turned on when the float ”floated”. However, the buzzer doesn’t work anymore. I’m thinking there isn’t enough voltage after the relay to go to the negative terminal on the buzzer panel? If that makes sense? Like the relay is robbing all the power. I kind of want the buzzer to buzz as well as trio the zwave sensor.

Any ideas?

I can’t imagine the relay drawing that much power to not have your buzzer make noise but ya never know.

How about first taking the relay out of the circuit and re-testing to make sure the float going high sets off the buzzer like normal. Once thats verified working are you sure the alarm panel is pushing out 12+ and then returning to ground? Is the input on the alarm panel just called “input”? Can you get a picture of it?

I think you need to put the relay across the float power and not in series with it. According to the coil spec that relay pulls 15ma @ 12VDC. Your essentially putting a 800ohm resistor in series with your buzzer. By putting it in parallel as long as your float can provide an additional 15ma or current your voltage to the buzzer will remain the same. That voltage drop across the relay coil is probably what is causing you buzzer not to work.

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Yea I believe this is the problem. And I figure I’d have to run it in parallel. It can’t figure out how to do it. I mean I know what it means to run it in parallel I just don’t know how to do it in this situation. If I connect it to, what I think, is parallel, it would basically just close the circuit and energize the relay and and trip the alarm constantly. See image… maybe I’m thinking of this wrong. image

Are there smaller relay’s that draw less power?

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