Help me to replace a thermal sensor for my swimming pool

Hi,

Sorry, my subject does not speak about arduino, but that's the only electronical forum I know.

My swimming pool uses a Innowater SMC device in order to launch pump and stop it.

You can configure it hourly or you can use a sensor in order to compute how many hours you need to make the water pump work.

But the problem is that my water thermal sensor seems to be buggy because it's written that I have 60 to 95° C which is not possible.

So I have to change this thermal sensor (136 EUR): SONDE TEMPERATURE CRYSTAL CONCEPT - NOIR ANCIEN MODELE - E-shop Piscine Ambiances

As you see, it's very expensive just for a water thermal sensor which can cost about 5 EUR...

So I ask the productor if we has some specs and he told me it's a NTC-10K thermal sensor that I need. I think it's linked to the device with a BNC connector.

Do you think it's possible to do it myself, buying a cheap thermal sensor and connecting it to a BNC connector ? Do you know where I can find for sure this kind of sensor.
It requires a specific connector to be plug in my swimming pool pipes, so I don't know where to find this kind of product...

Thanks a lot!

No.

Are you sure it's not simply set for Fahrenheit?

That sounds like a thermistor, cost less than £1 (one off) . You already have the old swimming pool specific connector. You could drill out the old thermistor and insert the replccement and pott with epoxy. Connect and attach the cable, you will probably need some heat shrink or the like.
All seems easily doable to me, based on what information is available at the moment.
Please let us know what you think and how you get on.

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That's what I checked first, but it's written °C on the device. And when I convert these degres (like 95°) to °C as if it was Fahrenheit, it's just wrong.
So I think the thermal sensor is just buggy. Notice that it changes from day to day, it was 60-65 a week ago, and now it's 95° ... The real temperature was about 15° one week ago, and now it's about 19°.

Great! I'll try that! I plan to unplug all this to check how this is connected and how it works.
I hope I can do that, maybe it's not possible to remove the thermistor from the connector. But I'll try to do that.

If it's not possible, I'll ask a friend who is plumber and ask him if we can change the pipes and connector which is in contact with the water. If I must change something with the water pipes, I prefer to ask him in order not to break something.

Thanks a lot!

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Swimming pools and electricity do not go together too well .
It is not a great idea to mess with stuff here as safety is uppermost and careful isolation is needed

Even if it's low voltage? because I think it's a low voltage on the thermal sensor. And it's also far from my house.

The thermistor itself would not be the first suspect on my list.

That's a good point! As an experiment you can temporarily replace it with a regular 10K resistor. It doesn't really matter what it reads but if everything else is working the temperature reading should be rock-steady. And of course it doesn't have to be in the water or any particular physical location.

What do you think ? You think it's the controller ? I can't open that, this is a proprietary device... I don't think it's good to be opened... I will check with a 10K resistor. Maybe there is an issue elsewhere.

The source of the low voltage an e an issue-failure of the transformer, earthing issues etc. The distance to your house is irrelevant and suggests you might not be aware of safety with pools - really only use approved equipment

ok, the manufacturer told me to send the complete device in order to check and to give me a new working thermal sensor for about 100 EUR. But as I use it this summer, I'll send it in october. It seems to be ok for them, so I'll probably do that.
Thanks!

I finally bought this : https://www.amazon.fr/gp/product/B019YDRBVE/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

It's the same connection for the water pipe, so I just had to plug a BNC connector on the other side. As you can see, it's very expensive compared to a simple NTC-10K, but there is this part which is easy to plug on my water system and I think I can change only the NTC-10K next time, because it seems to be removeable.

I just had to find a way to connect the 2 cables to a BNC connector which is quite easy.

It's working perfectly and I saved more than 100 EUR !!!

Thanks to everyone!

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