Newcomer to Zwave here, Vera 2 and various accessories that I am slowly getting to grips with
The intent is to use it all to control an air source heat pump (which dives the existing ratiators) and get fine control over the heating to lower bills while keeping comfort.
I opted for the Everspring ST814 temperature sensor as a room temperature monitor with the intent to use Vera to run different scenes for different temperatures at different times of day.
This is working very badly, the Everspring is reluctant to update temperature on Vera and that defeats the objective of fine control of heating. It sometimes fails to report back 3 degrees temperature change which is causing lots of overshoot.
I am thinking that I might be better off with something that classifies itself as a thermostat rather than just a temperature sensor and am looking for recommendations. If it were externally powered rather than battery operated it might do better at reporting back more often.
The heat pump is controlled via an appliance switch and a relay so I don’t need any boiler interfaces. I am happy to run it all through Vera provided I get the reliability.
I would want to vary the set point with different times of day. I would like to get actual temperature information out of it to log.
If it reported back in 0.1C intervals rather then 1C intervals it would give me much better resolution and allow the system to make better decisions.
Any thoughts from the people that have been here before would be appreciated, I am in the position of not achieving what I set out to do at the moment.
I had a similar issue with the ST814. To be fair, it’s not just the sensors problem - it does report to 0.1 deg resolution, but the Vera code reduces this to 1 deg. Because the sensor is on battery, it likes to reduce how often it sends updates.
I moved over to one wire systems using the EDS OW-Server (OW-SERVER: 1-Wire to Ethernet Server, Revision 2). The sensors are similar price to the likes of the ST814 (for a temp/humidity at least), but if you want a temperature sensor, then it’s only a few $$/££ once you’ve bought the OW-Server. The server links nicely to Vera over Ethernet, so it’s reasonably simple - although not as simple as a wireless system admittedly.
Below is a plot from my bathroom where I intend to control a heat recovery extractor fan - i’s monitoring the temperature and humidity to 0.1C and 0.1% respectively.
Anyway, that’s my thought - I’ve written a OWServer plugin which currently supports the temperature, and temperature+humidity sensors, although I hope to be able to support other types soon.
Thanks for those thoughts, that looks a lot better information than I am getting from the Everspring.
I’ve ordered one together with a couple of temperature sensors so it will be interesting to see how it works out.
Have you written any Lua code for temperature control yet? With scenes I end up using 2 per temperature so it might be nice to have a proper “thermostat code module” which allows centre temperature and dead band to be programmed and looks after both the on and off cycles.
Add into that “time of day” bands and it will be extremely useful. Maybe time I got into this coding.
Nice info! I may pick something up as I want to have more control of the temperature of my second floor which does not have a thermostat (single zone). I want to be able to adjust the thermostat downstairs to the temp average from around the house. I just wish they offered longer lengths for the sensors than the standard 12 foot (Not sure what the cost and minimum would be for custom order). Do you have your plugin posted for others to use?
Garret, it looks like you can use standard Ethernet patch cables to connect many of the sensors to the control unit and hence you can extend cables as needed.
I just wish they offered longer lengths for the sensors than the standard 12 foot
The One Wire sensors can be run quite long distances (1000 feet?), so it's not a problem there. As Nick points out, you can simply extend the cables - they actually use an RJ12 plug on the OW Server (it's smaller than the RJ45 Ethernet cable - it's the one used for phones in the US). You need to be careful with RJ12 though as they come in different flavours - phone versions only have 2 or 4 wires - the EDS OW-Server pinout uses the outer connections so you need a 6 pin version. You could probably find an RJ12 to RJ45 adaptor and then use ethernet cables... The EDS ENV type sensors don't have a cable - just screw terminals. I'm not sure what their temp sensors have on the end (bare wires or RJ12).
The nice thing is that you can buy the DS18B20 temp sensors off eBay for £6 for 10. These sensors are simple to wire up (3 wires!), are accurate to 0.5degC, and have a resolution of (from memory) 0.06degC. I’ve got one pushed in between my hot water tank and the insulation to measure water temperature, and I may connect a few more to pipes in the loft to keep an eye on them over winter!
Do you have your plugin posted for others to use?
The plugin is available - it's in the plugins board (http://forum.micasaverde.com/index.php/topic,8381.0.html) and I'll try and set up a repository soon. Also, the first version works fine with temperature/humidity sensors from EDS (and the DS18B20 temperature sensor), but other sensors aren't currently supported. I'm currently rewriting the plugin to make it more "universal" and add a few more features - I hope this to be done in a week or so (I just need to get my hands on some sensors to test it out).
Have you written any Lua code for temperature control yet? With scenes I end up using 2 per temperature so it might be nice to have a proper "thermostat code module" which allows centre temperature and dead band to be programmed and looks after both the on and off cycles.
Not yet. I'm waiting on a relay board to turn up, then I plan to use it to control a heat recovery fan in the bathroom, but I've not started this yet...
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