jondallimore wrote: ↑
Wed Mar 25, 2020 9:34 pm
from the pictures I can see, its a metal tube case with a bit of neoprene shrinkwrap around the join between the wire and the case. I would hope theres an o-ring seal inside there otherwise theres no chance it will remain waterproof when heated and cooled
I endorse DS18B20
There are different quality ones. I prefer the ones that have the sensor potted in a suitable resin within the stainless tube. I have a number of them in under-cover outdoor environments (three genuinely outdoors, a couple in unheated unsealed buildings, a couple in my garage). But I wouldn't put one inside a hot water tank.
I don't trust the ones that have plastic sleeving at the join to be waterproof - I think they are an 'enhanced robustness' option, but not a watertight.
For a hot water tank a sensor in a thermowell works much better than contact on the tank surface, in my experience - faster, more consistent response to tank changes. (Not a useful comment if your tank doesn't have a thermowell, I know).
For a pipe temperature then I cable-tie them to the pipe inside the lagging and it works quite well. It is worth putting thermal grease (or presumably some other suitable material - a heatsink gap filling pad probably works) between the sensor and the pipe. When I mount one to a pipe using thermal grease it gives a few degrees higher reading than done dry. It surprised my how much difference it made when I tested it (simply by mounting two adjacently on the same pipe, one greased, one dry).