Recommendation for Zwave relay for controlling gas heater using OpenHAB (Amazon Echo)

Forums › Gadgets, robotics, home automation, electronics (including wearables) › Recommendation for Zwave relay for controlling gas heater using OpenHAB (Amazon Echo)

lchiu7

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#204761 16-Oct-2016 10:58

I currently have a very simple OpenHAB system (with HABridge) run by a Pi and accessed primarily via a Amazon Dot.

The two devices I have are both wall switches, one an Insteon wall switch and one a Dlink module. Both are controlled by emulating a Hue bulb so just basic on/off controls which suits me fine.

I also have a gas furnace which is controlled by a low voltage relay which which I guess opens the gas inlet valve when closed. I would like to automate that also think a Zwave relay would do the job (I know I would have to install a Zwave hub also) which can be controlled by OpenHAB. Thus I could say Alexa, turn on the heater and bingo, the heater goes on.

Lots of searching but cannot find a suitable Zwave relay I could use. Do those who have more advanced installations have any suggestions on what relays I could use and where to buy them from? Or is there another solution I could use? It's just a relay - not switching mains power but I think it would need to be connected to a power supply to operate (probably mains power).

Thanks

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SumnerBoy

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#1651857 16-Oct-2016 11:04

If you are up for a bit of tinkering, and you have WIFI access at your boiler, I would look at using one of these plus one of these. Total cost about $US7.50 incl. shipping!

Then program it up with something like ESPEasy or Homie and you will have MQTT control/access of the Wemos. You can then spin up a instance of mosquitto on the Pi and use the openHAB MQTT binding to *talk* to the relay.

This probably sounds quite complex but it is relatively easy to setup. Setting up mosquitto on the pi should be easy enough and using the MQTT binding in openHAB is a piece of cake (it is probably one of the more commonly used bindings).

If you have programmed an Arduino before the configuring the Wemos shouldn't be too hard either.

Much more cost effective and will work just as well. I would only suggest going the Z-Wave route if you intend to add more in-wall light switches/relays and/or motion/flood/smoke sensors.

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richms

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#1651893 16-Oct-2016 12:47

Just make sure it really is low voltage before using the wemos relay shield. Its layout is crap with stuff all isolation between the terminal side of the relay and everything else. Like most power switching things out of china.

Richard rich.ms

lchiu7

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#1651894 16-Oct-2016 12:50

SumnerBoy:

If you are up for a bit of tinkering, and you have WIFI access at your boiler, I would look at using one of these plus one of these. Total cost about $US7.50 incl. shipping!

Then program it up with something like ESPEasy or Homie and you will have MQTT control/access of the Wemos. You can then spin up a instance of mosquitto on the Pi and use the openHAB MQTT binding to *talk* to the relay.

This probably sounds quite complex but it is relatively easy to setup. Setting up mosquitto on the pi should be easy enough and using the MQTT binding in openHAB is a piece of cake (it is probably one of the more commonly used bindings).

If you have programmed an Arduino before the configuring the Wemos shouldn't be too hard either.

Much more cost effective and will work just as well. I would only suggest going the Z-Wave route if you intend to add more in-wall light switches/relays and/or motion/flood/smoke sensors.

That's certainly cheap but it might be a bridge too far for me. I have never programmed in ESPEasy or Homie so I would have to learn that. Plus are there schematics around to show how the two boards are connected?

Presumably one is powered from the mini USB while the other has you connect to the switch you want to control?

I never programmed the Wemos. The HABridge server makes a number of devices look like Wemo devices. For the Dlink switch which has pretty ugly Alexa support (very wordy commands required) I found code in Javascript that used HNAP to send commands to the Dlink which I then added a commands to my OpenHAB configuration.

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SumnerBoy

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#1651940 16-Oct-2016 15:44

The relay shield plugs directly into the Wemos D1 Mini (note these are completely different products to the Wemo switches which are quite popular as well).

All you need to learn is how to program an Arduino - and by using something like Homie most of the heavy lifting is done already. The sketches are very simple to write.

Once they are programmed up then you just create standard openHAB items, bound to MQTT topics (via the MQTT binding), and you can control via your Echo and the the HA-Bridge.

But if you have never played around with Arduinos then it might be a little more than a simple task. Good chance to learn tho!

gregmcc

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#1651952 16-Oct-2016 16:22

lchiu7:

I currently have a very simple OpenHAB system (with HABridge) run by a Pi and accessed primarily via a Amazon Dot.

The two devices I have are both wall switches, one an Insteon wall switch and one a Dlink module. Both are controlled by emulating a Hue bulb so just basic on/off controls which suits me fine.

I also have a gas furnace which is controlled by a low voltage relay which which I guess opens the gas inlet valve when closed. I would like to automate that also think a Zwave relay would do the job (I know I would have to install a Zwave hub also) which can be controlled by OpenHAB. Thus I could say Alexa, turn on the heater and bingo, the heater goes on.

Lots of searching but cannot find a suitable Zwave relay I could use. Do those who have more advanced installations have any suggestions on what relays I could use and where to buy them from? Or is there another solution I could use? It's just a relay - not switching mains power but I think it would need to be connected to a power supply to operate (probably mains power).

Thanks

Careful, boilers and gas control are very heavily regulated, keeping in mind there are purge timers and air pressure regulators and all kind of safety's that are all controlled by a very specialised modulator, it not as simple as banging a relay in with the gas valve, if you get it wrong you are essentially making a bomb!!

lchiu7

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#1651954 16-Oct-2016 16:34

gregmcc:

lchiu7:

I currently have a very simple OpenHAB system (with HABridge) run by a Pi and accessed primarily via a Amazon Dot.

The two devices I have are both wall switches, one an Insteon wall switch and one a Dlink module. Both are controlled by emulating a Hue bulb so just basic on/off controls which suits me fine.

I also have a gas furnace which is controlled by a low voltage relay which which I guess opens the gas inlet valve when closed. I would like to automate that also think a Zwave relay would do the job (I know I would have to install a Zwave hub also) which can be controlled by OpenHAB. Thus I could say Alexa, turn on the heater and bingo, the heater goes on.

Lots of searching but cannot find a suitable Zwave relay I could use. Do those who have more advanced installations have any suggestions on what relays I could use and where to buy them from? Or is there another solution I could use? It's just a relay - not switching mains power but I think it would need to be connected to a power supply to operate (probably mains power).

Thanks

Careful, boilers and gas control are very heavily regulated, keeping in mind there are purge timers and air pressure regulators and all kind of safety's that are all controlled by a very specialised modulator, it not as simple as banging a relay in with the gas valve, if you get it wrong you are essentially making a bomb!!

I probably overstated this. It's just a in wall gas fired heater which uses a wall switch to operate a relay I guess which then opens a valve to allow gas to flow to the heater which is lit by the pilot light. When closed the relay then closes the valve. Seems like a very simple installation for a remote controlled relay using some home automation tool

Staying in Wellington. Check out my AirBnB in the Wellington CBD. https://www.airbnb.co.nz/h/wellycbd PM me and mention GZ to get a 15% discount and no AirBnB charges.

Aredwood

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#1652599 18-Oct-2016 00:28

Adding to the above - It could be the Robertshaw millivolt system - A thermoelectric generator uses heat from the pilot light to generate about 1 volt or so which is enough to keep the pilot valve open. and control the main gas valve via a switch. Have seen this system wired up to light switches and bimetallic strip thermostats.

Some mostly older gas central heaters use 24VAC as their control through the thermostat or a simple switch - The heater design often draws a couple of amps or so through the thermostat instead of using it as only a control signal.

And some heaters (normally gas flame effect fires) Use mains to either directly switch the main solenoids (with pilot for safety) Or a controller that preforms the safety functions.

So 3 different systems with wildly different voltages even after ignoring all of the often proprietary electronic control systems, which are often power and data running over a 2 core cable. (EG Rinnai infinity controllers, newer Brivis)

Does the pilot light stay lit all the time? Or does the heater light the pilot by itself? Either way safest to assume that there is mains power being controlled by that wall switch unless you have proved that it is definitely not mains.

lchiu7

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#1652892 18-Oct-2016 14:07

Very perceptive. It is the Robertshaw valve. I know this because

1. the fire stopped working and I called in a gas fitter

2. He proclaimed the valve faulty and could not obtain a replacement in NZ

3. I bought two on the Internet and had shipped to me (I have two gas flames) after eyballing them and woring out what they were

4. They then said they were not comforatble installing them since they had not provided them!

I then called another gas fitter to install them who discovered the valves were fine, it was just dirty pilot light burners and he cleaned them both up.

When I complained to the original gas fitter company manager they reimbursed me all the charges I had incurred for the visit but I was left with two valves. Luckily I was able to RMA them and return them on my next US trip (which luckily was only a month away from the time of the incident).

I watched the guy check the wiring out with a multi-meter and it's low voltage so the Zwave switch should be fine.

Staying in Wellington. Check out my AirBnB in the Wellington CBD. https://www.airbnb.co.nz/h/wellycbd PM me and mention GZ to get a 15% discount and no AirBnB charges.

Aredwood

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#1655443 21-Oct-2016 01:14

You will need to check that the Z wave relay is an actual mechanical contact relay and not a solid state relay. As simple solid state relays are cheaper than mechanical relays - (just a TRIAC and a resistor) But solid state relays that are intended for AC will only work on AC.

lchiu7

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#1655474 21-Oct-2016 07:58

Aredwood:

You will need to check that the Z wave relay is an actual mechanical contact relay and not a solid state relay. As simple solid state relays are cheaper than mechanical relays - (just a TRIAC and a resistor) But solid state relays that are intended for AC will only work on AC.

Pretty sure it's DC as there is no AC connected anywhere near the heater. As a previous poster noted, the voltage comes from the millivolts generated the piezoelectric device from the pilot lamp.

But still don't know which Zwave switch to purchase and where to get one.

Staying in Wellington. Check out my AirBnB in the Wellington CBD. https://www.airbnb.co.nz/h/wellycbd PM me and mention GZ to get a 15% discount and no AirBnB charges.