RDS
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Bonding a DS18B20 Sensor

Wed Jul 13, 2016 9:49 pm

I would like to use a DS18B20 Sensor to measure the Temperature of the Stainless Steel Caravan Hot Water Tank.
I have an External (Sealed) DS18B20 Sensor, that I would like to bond to the Tank.

Does anyone have any experience of a successful way to bond the Sensor onto the Stainless Steel Surface and what is the best product to use.

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joan
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Re: Bonding a DS18B20 Sensor

Wed Jul 13, 2016 10:21 pm

I have no experience but was wondering if that thermal paste used for heat sinks and such like might be appropriate.

rzusman
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Re: Bonding a DS18B20 Sensor

Wed Jul 13, 2016 11:14 pm

Just use epoxy, and then cover with aluminum-backed foam tape, to insulate the sensor from the environment.
I did this on my solar water heater panels, and it worked fine.

RDS
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Re: Bonding a DS18B20 Sensor

Thu Jul 14, 2016 8:15 am

@joan
Thanks, the paste would ensure good thermal contact but it would not hold the sensor in place.

@rzusman
Thanks, OK, I will use epoxy. It is the obvious choice but I was uncertain if it would be OK at the temperature, probably around 65 degrees C.

fruit-uk
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Thu Jul 14, 2016 8:40 am

My recollection is that the ground leg of the device provides the best thermal path for temperature measurement - so make sure this is close to the bit you want to measure

RDS
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Re: Bonding a DS18B20 Sensor

Thu Jul 14, 2016 9:36 am

@fruit-uk
The ones I have are the external version so the ground leg is not visible. The whole component is encased in a stainless steel housing, so that is what I will bond to the tank.

Major Tom
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Re: Bonding a DS18B20 Sensor

Thu Jul 14, 2016 11:43 am

Won't you just be measuring the temperature of the outside of the tank? Presumably it's insulated, so it will only be warm.

If you want the temperature of the water, try attaching the sensor to the outlet. If it's a metal fitting there then heat will be conducted from the interior along the outlet pipe so you'll get a better idea of the water temperature. When someone opens a tap then the outlet pipe will even more accurately represent what's inside the tank.

Ideally you'd put the sensor inside the tank, but unless the tank already has a thermowell or some other means of getting it in there you probably don't want to do that.

If you insist on putting the sensor on the outside, what about a strap running around the tank and pulling the sensor against it?
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RDS
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Location: Lancashire, UK

Re: Bonding a DS18B20 Sensor

Thu Jul 14, 2016 2:05 pm

@Major Tom
Thank you for your comments and suggestions.

Surprisingly, the Tank is not insulated, so the top of the Tank gives a very good indication of temperature inside.
Unfortunately I can only access (easily) the top of the Tank, so a strap around it is not possible.

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pluggy
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Re: Bonding a DS18B20 Sensor

Thu Jul 14, 2016 3:03 pm

You will have a lot more success with bare DS18B20's like this

http://www.ebay.co.uk/itm/5-PCS-DALLAS- ... SwYmZXFIW5

than the encapsulated type like this

http://www.ebay.co.uk/itm/DS18B20-18B20 ... 0784248550

if you're bonding them to the outside of a tank with epoxy.

Use a bare sensor with the flat side glued to the tank and then stick some foam or something over the top to isolate it from the surrounding air.
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RDS
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Joined: Tue Oct 06, 2015 8:17 am
Location: Lancashire, UK

Re: Bonding a DS18B20 Sensor

Thu Jul 14, 2016 3:44 pm

@pluggy
I have both types already.

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