Measure Temperature - Single Device or Combo?

motionsensor
temperature

(Tony) #1

Can anyone recommend a temperature only device or is it best to stick with the combo Motion and Temp sensors?


(Eric) #2

if the combos work then why not? Seems like there is no cheaper temperature-only wireless transmitter for less than a combo.

The Smartsense open/close sensor made it easy to monitor freezer or fridge temp AND the door status at the same time, one mounting. One sensor is better than two in that case, fewer batteries.


(Tony) #3

Eric - that’s why I asked - I haven’t found temp only sensors per se but there are other considerations like battery life, and if someone has already gone through the exercise, why not learn from them. :slight_smile:I do appreciate your input - in the absence of any other info, that was my conclusion.


#4

Depends on the use case and the accuracy needed. Each sensor should publish their plus/minus specs, but a lot of people don’t read them.

If you need precision accuracy, I would look at the Kumostat wireless tags. These are very well engineered, have exceptionally long range, have an IFTTT channel and a good community-created ST integration.

http://wirelesstag.net/specs.html


(Tony) #5

JD - Thank you - I didn’t know about these. Thank you.


#6

I forgot to mention (sorry, I’m tired today) that the kumo tags are expensive because you have to buy one of their $60 ethernet bridges as well as the $40 tags. (Just One bridge for up to 40 tags) So if a regular zigbee sensor would work for you, that’s almost certainly going to be cheaper.

But if you need longer range or more precision, the Kumo tags are a good solution for many use cases. So just depends on what you need. :sunglasses:


(Tony) #7

JD - those tags will work for another project - but I’ll use something cheaper - I just need to kick on an exhaust fan when it gets “warm” in the “server room” +/- a few degrees isn’t important in this case and the distance to the hub is just a few feet (less than 10) in this case. Thank you!


#8

Just in case you don’t already know this, it’s best if you can keep any other devices at least 10 feet from both the SmartThings hub and your Wi-Fi router.

This is for two separate reasons. The Wi-Fi router has a really strong transmission, so even if it’s not in exactly the same band, it can create some interference. And it is in an overlapping band with Zigbee so it’s especially bad for that.

As for hubs placement is action entirely separate issue. The antenna being used are Omni directional (360°) which is great, but the signal spreads as it moves out from the hub.

That means if you put a device 8 inches from the hub, it might actually miss the signal where if you put it 8 feet away, it’s more likely to be in the zone.

As I said, you may already know all that, but I just wanted to mention it. A lot of times people think it works like soundwaves and the closer you are the better you’ll hear it but it’s not quite the same.


(Tony) #9

JD - Thanks again - I appreciate the info. n8xja - is my ham radio call/license and aware of the some issues with RF, but not an expert by any case. Is luck or good engineering, I’m using a Sophos Enterprise grade UTM (free for home users) as a vmware guest OS. The access points, happily are no where near the ST Hub - that’s the lucky part.

I do have a current issue where I’m trying to control an outlet that toggles power to a 90Watt LED Street light. I installed one of those z-wave outlets on an outside wall, up high - hoping it would repeat the signal to the utility pole that’s about 100’ away. It works about 85% of the time, so I"m just on the edge. What I didn’t know for sure is if the outlet installed on the exterior wall actually repeats/extends the z-wave network (I haven’t looked at the specs yet). I sort of wish there was an “show how the devices are interconnected” to help me understand that part of it.

Thanks for the blog article on the repeaters - it’ll help fill in any gaps.


#10

The community – created wiki has some additional information:

http://thingsthataresmart.wiki/index.php?title=Repeaters

100 feet is pushing it. Z wave uses FSK, zigbee uses DSSS, so even though Z wave plus technically has a longer range than zigbee home automation, it tends to get disbursed by humidity, rain, and snow. So you’ll see that most outdoor sensors, for example, are zigbee.

There are some members using zigbee pro devices with antennas for long range applications but the technical set up is complex.

http://thingsthataresmart.wiki/index.php?title=How_to_Automate_an_Outbuilding


(Tony) #11

I just read the blog - as i’m running out the door, so z-wave never looks for a better repeater/parent. I don’t think I cycled the power on the end device since installing the repeating device.


#12

For zwave it’s not enough to just power cycle, you have to issue a specific “zwave repair utility” to update the neighbor tables.

You should run this utility anytime you add/remove a device from the network, or you physically move a device to a new location.


#13

Forgot to say…in zwave, the controller keeps the master address table for the whole network. Then each of the other devices keeps a mini table that has just their own neighbors in it. When a device goes to send a message, it checks its own neighbor table to find a repeater. If that repeater is busy, it will check its neighbor table to see if there is another repeater nearby and then try that one.

What it won’t do, however, is update the neighbor table just because a new device moved into the neighborhood. The original device will just keep using that same old neighbor table until the controller tells it to update that neighbor table with Z wave repair utility.

This topology is used to maximize battery life on the end devices. Sensors don’t have to keep scanning the neighborhood to see what’s there. They just work off of their neighbor table.

So it’s not predefined or rigid routing because the device can try an alternate route if the first one is blocked. But “alternate” is limited to the devices already in its neighbor table.:sunglasses: