Spa temperature sensor

[fdarden]

After some experimentation, I believe the probe I have is actually a 2.2K probe. Seem the rating of the probe is done with its resistance at 77 degrees. Mine is sitting in this general area in ambient air in my home, so I have to assume that s the case. Assuming I am able to establish a table for this thermistor, how do I make the adjustment in Homeseer? What was posted earlier appears to be a script. Sorry if these are simple questions, but I really do not understand this aspect of the software, however it is very important to me to get this, or a solution like it working. The MIMO was ideal in some ways as it is AC powered, and does not use batteries. Should I really be considering 1-wire instead?


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[JHughes]

A couple of questions to try and help sort this out with you. What voltage are you running the sensor on. If you disconnect the temp sensor what reading do you get. Which pool sensor did you buy.
Looking at the specifications for the mimo it is a non linear reading based on input voltage. The pool sensors are a non linear inverted resistance. There will be some conversion required to get the 12 bit reading back to voltage then to temperature.

[mrhappy]

After some experimentation, I believe the probe I have is actually a 2.2K probe. Seem the rating of the probe is done with its resistance at 77 degrees. Mine is sitting in this general area in ambient air in my home, so I have to assume that s the case. Assuming I am able to establish a table for this thermistor, how do I make the adjustment in Homeseer? What was posted earlier appears to be a script. Sorry if these are simple questions, but I really do not understand this aspect of the software, however it is very important to me to get this, or a solution like it working. The MIMO was ideal in some ways as it is AC powered, and does not use batteries. Should I really be considering 1-wire instead?


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This is not a trivial thing so don't feel like it is your understanding of how HS works, it is not unheard of but not a thing that is done every day either.

Personally (and a second opinion is more than welcome) is i'm not sure you are going to get anything approaching accurate conversions with the fact the ADC is not linear (which the documentation suggests). The way you would calculate a reading based on a device having a linear response is when you know that 1 bit of data is worth x volts. You work it out on the basis that for 12 bits it is 16V (assuming you are going across the full input range) / 4096 which is 0.00390625V per increment. Because it is not linear and the thermistor is also non-linear (but not following the same curve) then it is going to need some testing, measurements and calculations to work out the two and see what you come up with. That could be a lot of pain (and I'm not sure where to start, guess you would need to find an equation for the ADC curve to start with) for something that never works out exactly right, you might be able to get a simple hot/cold indication easier but that might not be what you are after. I could however be talking out of my proverbial and there is some miracle formula somewhere.

To actually get HS to do some conversion you would have either an event that triggered when the ADC input changed value or do it on a recurring event. That event would trigger the script, the script would do the conversion and in turn update a second device.

Should I really be considering 1-wire instead?

Possibly, it has pros and cons just like anything else. If I was in your situation and the temp sensor you already was better suited (because of the way it was plumbed in or whatever) to the application then I think personally I would look at using an Arduino/Particle Core or something like that. That could accept the temp sensor on the input, perform the calculation itself and then send the calculated temperature into HomeSeer. That of course is then reliant on you having USB or Wifi range where your pool is.

[fdarden]

Thanks for the idea. I had hoped to buy a solution, plug it in, plumb the sensor, add it to my Z-wave network, and be done with it. Since that is not reality, and I really don't see any solutions that make sense for me, or that do not require heavy lifting. If I have to do heavy lifting, I agree. An Ardunio based solution might be more worthwhile. I had found this project, which was very appealing to me. I'm not sure how I would get this to report to Homeseer, but something like this would be pretty neat. This sort of project is within my abilities, I just had no idea that something as simple as pool temperature would not have been commercially addressed with the multitude of Z-Wave products on the market. At least with this project I can get more than just temperature for the hard work, however there is not a clear pathway to move this data into Homeseer.

http://www.instructables.com/id/Buil...-Pool-Monitor/


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[mrhappy]

Thanks for the idea. I had hoped to buy a solution, plug it in, plumb the sensor, add it to my Z-wave network, and be done with it. Since that is not reality, and I really don't see any solutions that make sense for me, or that do not require heavy lifting. If I have to do heavy lifting, I agree. An Ardunio based solution might be more worthwhile. I had found this project, which was very appealing to me. I'm not sure how I would get this to report to Homeseer, but something like this would be pretty neat. This sort of project is within my abilities, I just had no idea that something as simple as pool temperature would not have been commercially addressed with the multitude of Z-Wave products on the market. At least with this project I can get more than just temperature for the hard work, however there is not a clear pathway to move this data into Homeseer.

http://www.instructables.com/id/Buil...-Pool-Monitor/


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There is a one wire Z-Wave interface for DS18B20 sensors made by Fibaro, I am not sure whether it made it to the US though http://www.dreamgreenhouse.com/reviews/2012/fibaro_us/ http://www.fibaro.com/manuals/en/FGB...sor-en-1.2.pdf and even if it were available I would search around to see whether HS plays nicely with it (Fibaro have an evident track record). There does appear to be a gap for good Z-Wave GPIO interfaces, I have an exact application for one at the minute and I am right at this moment building a Particle Core based solution because of that gap. As such this very topic is fresh on my mind!

That solution on Instructables is nice, I had written scripts in the past to deal with Pachube which was a previous incarnation of Cosm so it is possible to get data from that service into HS albeit you might as well intercept it and just send data to HS directly. People on here can probably help you with that, I've done it with a number of different devices - it might be an amendment to the existing code on it but this is the sort of stuff I love doing!

It'd be best figuring out exactly what parameters you want, what hardware you have, what ability you have to make a connection to HS where your pool actually is. If you don't have USB/serial then that restricts you from the cheap solutions, if you are in Wifi range then you can look at some of the solutions like the Particle. The actual software side of HS can be done with a script and is relatively straightforward.

[jon00]

Unusually, it is easier to do what you here in Europe with the Fibaro Universal Sensor which among others, provides a 1-Wire to Z-Wave interface (as Sooty posted earlier).

Edit: and now MrHappy!

[fdarden]

The Fibaro Universal Sensor seems like it would be great to solve this issue. Does anyone know if Homeseer supports it, and if it is or is not Z-Wave Euro only?


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[beerygaz]

Anyone know of a 1-wire sensor that can be plumbed into the pool PVC piping though? Or is there. Simple way to convert the thermistor data to 1-wire? The DS2450 perhaps?


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[mrhappy]

Anyone know of a 1-wire sensor that can be plumbed into the pool PVC piping though? Or is there. Simple way to convert the thermistor data to 1-wire? The DS2450 perhaps?


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Would you not get a reasonably accurate measurement just by clipping to the pipe externally and covering it? I don't know the specific heat capacity of PVC pipe and of course subject to external variations but I wonder if that would just not be easier to give you an idea of the temperature (unless it has to be accurate to be used in a thermostat?).

[beerygaz]

PVC is a pretty poor conductor so you'd need something plumbed in even for 'should I go for a dip' estimations.


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[fdarden]

It seems like this solution that I posted earlier solves that issue somewhat. It at least provides you with a metal surface that is exposed to the water inside. It looks like you could possibly adapt many different probes as long as they fit inside the metal sleeve. http://www.heatmypool.com/solar-heat...kit-p-524.html


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[fdarden]

I thought about this for a little while, and I have had some experience using these "PG" style glands for diving lights. They can easily hold 30 psi, and would allow any probe to be placed into the water stream. This is one I pressurize to test oxygen cells with and it is rock solid.




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[fdarden]

Spa temperature sensor

I have not been able to locate a FGBS-001 that is not 868MHz (EU Zwave) so that is off the plate for me.


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[JHughes]

Entering the value returned by the mimo inplace of x should give you the voltage (y)

Just need to figure out the voltage to temp conversion

Y = 0.24(1.0011^X)
correlation = 0.9553

[JHughes]

Link to equation to convert to temp

http://electronics.stackexchange.com...ntc-thermistor