Home Automation and the Blue Connect Water Analyser

[snaxmuppet]

I got one of these recently and wanted to share my experiences and also see if there are others out there using one.

We have had our spa now for about 7 months (Hotspring Limelight Flair). I have a home automation system (part self-built) and a solar PV generation system. We also have time-of-use electricity tariff which changes our electricity tariff every 30 mins depending on demand (Octopus Agile).

When we first got the spa we started out following the dealer's recommended instructions using dip sticks in the normal way to test FC, TA pH etc but with my interest in automation I soon started looking at how I might integrate the spa into the home automation system. I could see scope for auto-monitoring some of these parameters and even possible automating the on/off cycles of the spa to avoid running the spa during the most expensive periods or making the most of our solar PV generation.

I already have in place the following:

• A QNAP server/NAS that is on 24/7
• Node-Red up and running on the server
• A MQTT broker on the server (Mosquitto)
• Vera Home Automation Server
• Hive Active Heating
• 9kWp Solar PV with solarEdge Inverter 

I won't go into my Home Automation system in any more detail than needed to explain what I have done with the spa. If anyone would like more info then please get in touch privately and I'd gladly tell more.

So what have I done...?

 

Heating

I wanted a way to turn off the spa at the times of day that was most expensive. My electricity tariff changes it's price every 30 mins throughout the day to discourage electricity use at peak times. There is a REST API available where I can get the 30 min period price and so it is easy to use Node-Red to turn the spa on or off depending on the current electricity price.

I also wanted to make sure that the spa was left on at times when the solar PV was generating surplus power so that the spa could use that power instead of exporting it to the grid. My solarEdge system also has a REST API where I can interrogate the inverter to determine whether I am importing or exporting and by how much. From this is was easy to use Node-Red to ensure that the spa was turned on when there was sufficient surplus solar power.

The turning on/off of the spa is via a z-wave 40A switch which is connected to the Vera controller. When Node-Red determines that the spa should be turned on or off it sends a request to the Vera controller and that controls the z-wave switch.

This all works pretty well. It means that when there is sufficient solar power to heat/run the spa it is always left on and it is also left on outside peak electricity periods (mostly 4pm - 7pm).

The main issue is that the only control I have over the spa is turning the power on and off. I have no automated control of the heating temperature. The spa is designed to be on 24/7 and while it is powered down the circulation pump is not running. What I would really like is to have a way to automatically control the heater and that would allow me to turn off the heater at peak times but leave the circulation pump running. I am not sure if turning off the power to the spa in this way is likely to harm it. I did wonder whether the heater may overheat if power is cut while heating. It is only a 1600W element.

Anyway, so far so good. I am going to look into installing a z-wave switch into the heating element circuit to allow me to control the heating element independently.

 

Monitoring

The vast majority of hot tub owners test the water balance and FC using test strips. They are not the best way and depending on the quality of the test strips are not particularly accurate. But for most people they give ballpark readings and that is often good enough. A better way to test the water is using a titration test kit such as the Taylor K-2006 which would give you pretty accurate values the kits are quite pricey and not easily available worldwide and they are a bit fiddly to use.

I knew when I got the spa that I would soon get fed up with using the test strips and couldn't see myself having the patience to use the Taylor kit regularly (if I could get one here in the UK!) so I needed a more automated way to monitor at least the FC and pH on a daily basis. There are auto-chlorinators available for pools and for commercial spas but very little for normal, residential spas. Of what is available, it seemed to me that the simplest way to auto-measure was with a Blue Connect from Riiot Labs. This device floats in the spa or pool (works for both) and sends regular data of water condition to the cloud via SMS or you can use Bluetooth from your phone. An app on your phone gets and displays that data allowing you to monitor on your phone the condition of the spa water from anywhere. Clever.

The Blue Connect measures temperature, pH and ORP or redox. Temperature and pH is good but it isn't ideal that it measures ORP. ORP is not a measurement of FC but once you have calibrated it against your pH and FC levels it can give a reasonable idea of FC and sanitisation capacity of the water. ORP is not easy or simple to use and I am not suggesting that you can just read an ORP level and determine the chlorine state of the water but it is a very useful indication once you get to know what ORP readings equate to what FC/pH/CYA levels.

So now I can see the temp, pH and ORP condition of the water on the phone but I have not yet integrated it into the home automation system. There is a REST API for this but Riiot Labs have not published the details, at least I cannot find them, but I know it exists as there are others doing this kind of thing too. There are some IFTTT actions so it must exist! Once I have details of the API I will be able to use Node-Red to read the data from Riiot Labs and use that to notify me if any of the values go out of range.

 

Conclusion

So none of this is ideal. Turning the spa off when the electricity price goes high or when there is insufficient solar power probably is not the way to go with this long term. I need to put a z-wave switch into the heating element circuit so I can  turn off the heating in isolation. Also, the Blue Connect is a significant step forward with automatically monitoring the water condition but there is more work to do on that too. I need to continue to get to know how the ORP reading equates to the FC but I already have a good feel for that. Also, I need to find details of the REST API from Riiot Labs so that I can get the data into my home automation system.

But it is a good start  

 

[KatherineHunter]

I would be interested to know about the solar panels you use. What area they cover and how much electricity they get. I live in a reasonably warm climate. Usually, there is not a single cloud in the sky that would interfere with receiving solar energy. I want to automate some processes in my spa, and I was very inspired by your post. Should I buy this controller https://www.automationstop.com/shop/allen-bradley-plc/1764/1764-LRP or save some money and take a variation that will be cheaper? My budget allows me to buy an expensive model, but why not leave some cash for other expenses. Thank you in advance. Great post!