1-Wire temp sensor recommendations

[Rob]

I need some 1-wire temp sensors, mainly to attach to pipework so am looking for some reliable cost effective sensors which will work seamlessly with the Loxone 1-wire extension.

Any recommendations?

[Tomasz Nowak]

I've never used, but I'd take a look at WireGate stuff

https://shop.elabnet.de/1-wire/serie/lserie

or

https://shop.elabnet.de/1-wire/serie/kserie

[TomM]

You can use literally any DS18B20 temperature sensor, just look on Google/eBay/Amazon.

The smallest, cheapest option is probably:
https://www.ebay.co.uk/itm/184390671951 (76p per sensor)

Or this is probably the most sophisticated you'll need:
https://www.ebay.co.uk/itm/122628774993 (£5 per sensor)

Both of which can be zip tied to a pipe to give you a temperature.

I have both these types running on a 1 wire extension and they work just fine.

[Medes.net]

Just a note of caution on 1-wire devices from ebay & the like.

I have a client who bought some of the ebay ones and had considerable issues with them and their reliability, the savings he made were lost in time spent chasing faults and actually increased cost overall when he then bought ‘Official’ ones from Loxone.

I have both loxone and some ebay silicone versions in my own install without issue, the trouble is with ebay et-al it is hit & miss. Never install them for a client!

Sent from my iPhone

> On 13 Oct 2020, at 19:23, TomM <t...@altuminteractive.com> wrote:
>
> You can use literally any DS18B20 temperature sensor, just look on Google/eBay/Amazon.

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[Tom Marianczak]

It's a fair point, you should be cautious of buying any unbranded electronics off eBay etc of course.

However, just to be clear, 1-wire is a standard manufactured by Maxim Electronics so you could buy their's and be pretty happy too.

That said I've had 20+ eBay sourced sensors installed for nearly 5 years now without a single issue whatsoever.

The bigger problem is the star wiring topology recommended by loxone...

Sent from my mobile device

[Deac99]

I had bought cheap sensors from ebay (under $1 each) have roughly 40 of them installed and never had an issue with any.  I do have 2 - 1 wire extensions as each has a limit of (sorry - can't recall how many off the top of my head).  I believe the people who have had issues with "Cheap" sensors would have had the same issues with expensive sensors as well because Loxone advertises that you can install in Star configs and pretty much any config you want.  I had trouble initially as I had a mix of star and bus configs.  Come to find out if you look at the 1-wire spec. it is really made for a bus type config and you need to minimize the length of wire for each of the sensors.  They usually come with a meter of wire, cut that down to 10 or so cm and install in a bus config and you won't have any problems.  Mine have been working for about 4 - 5 years with no issues at all.  Oh and if you put them all in a bus config and you minimize the length of the sensor wire you can have many more on each 1 wire extension than is advertised.  Right now I've got sort of a hybrid due to the learning curve but as I'm remodeling the various locations I'm changing everything to the bus and minimal sensor wire length.  

I had a design guide that showed the loading for each sensor but unfortunately I cannot find it at the moment to include with the post.  Basically it was written by the person who invented the 1-wire protocol and he states that the bus configuration with minimal stub lengths is the optimal configuration.  I was surprised that Loxone advertised the star config but with a reduced number of sensors, they can get away with it.

[Duncan]

something like this 

https://www.aliexpress.com/item/32827810300.html?spm=a2g0o.productlist.0.0.5f693483hFndRi&algo_pvid=c484f361-50b7-4ac8-95d4-17770d4a892c&algo_expid=c484f361-50b7-4ac8-95d4-17770d4a892c-1&btsid=0b0a0ae216026548970497635ea8fb&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

the waterproof ones tie-wrapped to pipework is probably the  easiest and cheapest solution

and as already said, 

do NOT star-wire them as per Loxone instructions 

keep each sensor cable cut down as much as possible

solder connections rather than use plugs/sockets if possible

https://www.maximintegrated.com/en/design/technical-documents/tutorials/1/148.html

[Rob_in]

On Tuesday, 13 October 2020 at 20:43:48 UTC+2 TomM wrote:

It's a fair point, you should be cautious of buying any unbranded electronics off eBay etc of course.

I've bought loads of electronics modules from AliExpress. I generally look for parts that have loads (sometimes thousands) of orders with very close to perfect feedback. Temperature sensors (DHT & 1-Wire), MQ135 sensors, OLED displays, Arduino, optocouplers, relays, DC-DC converters, Z-wave products, etc, etc. Some have been to integrate with Loxone and some were for standalone projects. In my experience they all work as advertised. A couple of times things have failed to turn up but I got a refund in those cases anyhow.

Don't forget stuff is so cheap there you can afford to take risks - those elabnet.de sensors are literally 10 times more than you'll find direct from China. The only downside for me is the shipping time so plan ahead :)

Robin

[David Wallis]

I've used just that sort of sensor, I did the same but used foil tape to connect them to the pipe and then replaced the insulation around the pipe.

[Rydens]

I have  strapped to pipes  these  from Amazon UK https://www.amazon.co.uk/gp/product/B00CHEZ250/ easy and work well.

[Evert van Es]

On the first project I worked on I installed a bunch of 1wire temp sensors with long wires in a star configuration. All with no troubles at all.

However on a recent project I went the same route and am now having intermittent results where some sensors occasionally report a temp of 25 degrees C.

I think this is a result of low quality sensors, I can see a difference in the thickness of the three connecting wires.  Unfortunately I have installed some of these sensors in unreachable underfloor heating, a wise lesson for the future...

I have yet to find a solution for these problems. I also read the 1wire network needing a resistor? The other option I have is to isolate the bad un replaceable sensors in their own 1wire network. Not a job I am looking forward to.

[amb5l]

I have used many of DS 1 wire chips on a very long (>100M) daisy chain without issue - once I threw the eBay ones away and purchased from Maxim/Dallas.

[RSin]

I used the aliexpress type although the standard ones not in the metal tube, metal tube is probably better where you have space as it has cable so would save soldering. I did have one batch that had intermittent faults, checked everything and turned out to be the sensors, the seller acknowledged this and since ordering more have not had any issues (i've had 40 from the same seller with no issues). Even big companies get it wrong occasionally and have recalls on batches so I wasn't put off. I don't believe any of these things come from different factories just because they have an expensive badge.

these sensors

https://www.aliexpress.com/item/32523899337.html?spm=a2g0s.9042311.0.0.27424c4dD30Qli

glued on with:

https://www.ebay.co.uk/itm/Thermal-Conductive-Heatsink-Glue-Adhesive-Compound-10-grams-tube/121052275338?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

@EVERT

 "intermittent results where some sensors occasionally report a temp of 25 degrees C " 

I get this from time to time but think its more of a loxone software bug. A few rooms at a time will state 25degC which seems very precise for a sensor to fault to that temperature. If you have stats enabled and click to show the graph it will show the actual temp e.g. 21.6degC, and when you go back to the previous screen the 25 has miraculously changed to 21.6

[Rob]

Thanks everyone for the really helpful feedback and recommendations.

I've not been able to get online much this week but should hopefully be able to read through the posts again in more detail over the weekend.

Cheers

Rob

[USMC0602]

I am trying to add some of the metal probe type sensors to a bus topology of 15 other DS 18B20 sensors bought from Loxone. When I add the metal probe type into the bus, parasitically wired like the rest, and run the ‘1-Wire Search’ all devices disappear. When I add a new DS 18B20 with the exact same wiring and run the search, all are found including the new one. 

The temp probe has a 2M cable attached and I have followed the wiring diagram to presumably connect the the correct GRD and VDD wires. 

Anyone seen this before?

Many thanks,

Andrew

[TomM]

Yes, almost certainly you have the wires around the wrong way.

I had this issue several times in the past, tried different combos and found one that worked, no harm done to network. Also, when a sensor was attached incorrectly I found it heated up to a high temperature rapidly so was easy to understand wiring was incorrect.

DISCLAIMER: this was my experience and the way I resolved it.  If this blows up your 1 wire network then I take no responsibility! Sorry!

[Vahur Kivaste]

I also had a problem with some Loxone 1-wire probes - they connected to the network but temp readings were way too hot for what had been normal. Pulled them out of the tubes in the floor and they were hot like TomM described. Changed the wiring (to parasitically I think) and that fixed the problem. 

[USMC0602]

Thanks for the replies. Confirmed bad batch from the seller.