Heat probe placement.

[Moneypit]

Anyone aware of any tests done to ensure best heat probe placement?

I keep seeing posts to place the heat probe for a UTH on a glass tank outside the tank and between the glass and UTH.

This type of placement presents a few issues in my mind.

It's measuring the temp of the UTH, not the glass, and not the internal surface of the tank

The UTH will be hotter than the glass so that's why (I think) the probe is measuring the UTH.

In this scenario, the probe could be taped on the outer side of the UTH if it is in direct contact with it. It is now service accessible for any reason.

Probing the inside surface of the tank over the UTH is most desirable (I think) because this is the temp the BP will see. It is also less likely to be impacted by ambient temp changes and the differences in temperatures the inside glass surface will see because of it - at least in the north east where I'm located. Part of my logic here is that the tank acts as one large heat sink and the temperature swings on the inside can be drastic from what is happening at the UTH

As an example, in my corn snake set up, a UTH directly on the glass resulted in an unregulated temp that fluctuated from 114-134 (no snakes during testing and set up). This was on the inside glass directly over the UTH. I tried several materials and thicknesses to place on the glass over the UTH and found that 1/4" aluminum plate sized 1" larger on all sides resulted in a surface temp that stayed between 81-86 (unregulated)

I have been checking the temp using an industrial surface probe and a temp gun.

My BP set up while in the glass tank will have a thermostat controlled heat pad on the hot side and thermostat controlled CHE offset to the"cold" side. It's permanent home will add a regulated UTH on the cold side.

Is there any reason why the heat probes are not being placed in the glass enclosures?

Thanks in advance for any experience and advice you share


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[PitOnTheProwl]

The problem is you and everyone else are really over thinking this and too trusting in the setting on your thermostat.
You use a non contact thermometer to get your actual reading and fine tune your stat settings to get the surface temps you want.
Its not that hard. You can place it on the outer side of the heat source too.
There is no service needed on the probe and if you use foil tape on your mat then there is no problem removing them for any reason either.

[Archimedes]

I found that when I attached my thermometer probe inside the tank on the hotspot, my big girl would dislodge it and I would wake up to a little heart attack about the temp being so low,when in fact it was just shifted off the UTH. I've moved to tubs and placed the probes between the tubs and UTH, and since that point I have figured out what temp keeps the hotspot in the tank at 88-92 as measured with a temp gun (113.7 for my setups.) It's personal preference, but easier than dealing with it being pushed away, or struggling to clean around it if it's hot-glued to the floor.

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[Moneypit]

The problem is you and everyone else are really over thinking this and too trusting in the setting on your thermostat.
You use a non contact thermometer to get your actual reading and fine tune your stat settings to get the surface temps you want.
Its not that hard. You can place it on the outer side of the heat source too.
There is no service needed on the probe and if you use foil tape on your mat then there is no problem removing them for any reason either.

Agreed that we'd should all be frequently checking and verifying temps. To clarify, I am measuring temps using surface contact with an instrument designed specifically for that purpose (Atkins series330) and a non contact method (Raytek mini gun).

My concerns about probe placement are to minimize cycling and temp swings by probing the heated surface and not the heating element. Just seems that all the guides and posts refer to measuring the temp of the heating element.

I know the UTH won't be serviced. But, my thought was if the probe, thermostat, enclosure etc required some kind of interaction (clean, adjust, replace, etc) it would be better to have it easily accessible.

And yes, maybe we are all overthinking this.

[Moneypit]

I found that when I attached my thermometer probe inside the tank on the hotspot, my big girl would dislodge it and I would wake up to a little heart attack about the temp being so low,when in fact it was just shifted off the UTH.

If I go this method (probe inside) I'll have to be sure it is secure. I've been considering using an aluminum plate like I do with my corn snakes and recessing the probe from the bottom of the plate and running up behind a background or even a PVC tube that is hot glued in a corner.

[NH93]

The age old question...

I personally use 2 probes; one on the outside and one on the inside. My ball python rarely uses the hot spot though, so I have no issues with dislodged probes. Just lucky there, I guess.