Dimming thermostat sensor

[DiXX]

Hi
I decided to change my thermostat from a Komodo dimming stat to habistat dimming high range stat , I’ve got instructions on where to put the sensor but I’m not sure. It says the sensor should go where the basking bulb is ? but in this vivarium and my other vivariums in the past I’ve had sensor where I want the ambient temperature to be , So which is right ? I thought as long as the ambient temperature is right it doesn’t matter about the basking bulb end. As long as it don’t go above 105-110 degrees.

 

[kingofnobbys]

Both approaches will work for closing the (control) loop.

If you are controlling the basking spot temperature , place the probe directly on the basking spot and set the Upper and lower control temperatures appropriately ( generally 4 or 5 degC range I would think ).

 

[DiXX]

Ok thank you

 

[DiXX]

So does the digital thermometer probe still go at the basking end ? If I’ve got the dimming thermostat probe under the heat source? sorry if that sounds dumb.

 

[CooperDragon]

I put the probe controlling the basking light right on the basking surface and then program it to 100-103. If your thermostat probe doesn't display the temp, you can put the digital thermometer probe right next to it to get the reading. Otherwise you can use it to monitor the cool side surface to see the gradient, or you could use it to monitor another part of the tank as you see fit. The goal is just to be able to monitor the gradient across the tank more easily.

 

[DiXX]

So excuse Dobby but is that right ? The thermostat probe is behind Dobby and the temp probe is the other smaller 1.

 

[CooperDragon]

I would either put them right on the log (zip tie or rubber band maybe?) or take into account that the readings will be a few degrees cooler at the probe than it is right on the surface and compensate accordingly.

 

[kingofnobbys]

So excuse Dobby but is that right ? The thermostat probe is behind Dobby and the temp probe is the other smaller 1.

You are measuring radiant heat from the globe + conducted surface heat from wall in that configuration.

I'd have the probe set up like this : (measures the combination of radiant and convection heat transfer ONLY)

Probe not in contact with any solid surfaces.

If you do as Cooper suggests, be aware it will take a while for the branch or basking surface to heat up or cool down , and you will be measuring ONLY radiant heat transfer + surface temperature , but not convective heat transfer from warmed air circulation (as the probe will likely be inside convective and air circulation barrier layer (in a stagnant layer of warmed air with very little flow).
See this for the physics of the situation (an approximation) :

I that case I'd also monitor the air temperature using another probe.

 

[DiXX]

So put the probe 2” above floor level Behind the log ? Or would the log block the signal ? The cable for the probe comes through the vent at the bottom of the Viv. I can have it go through top vent then down ?

 

[kingofnobbys]

So put the probe 2” above floor level Behind the log ? Or would the log block the signal ? The cable for the probe comes through the vent at the bottom of the Viv. I can have it go through top vent then down ?

Either (up or down) so long as the probe is in direct light from the basking globe and not touching a solid surface if you want to measure only radiant + convection heat.

If at near floor level in the warm zone, if you have it in the shade of the "log" and not touching any surfaces , you are going to measure the air temperature there ONLY.
If at near floor level in the warm zone and not shaded (direct line of sight to globe) and not touching any surfaces you are going measure the combination of air temperature + radiant heat at that location.

 

[DiXX]

Ok. So say I put the probe in direct light how will I get the probe to stick straight out ? Could I drill a probe size hole in the side wall of the Viv and poke the probe through that ? I was never any good at physics at school. Ha ha

 

[kingofnobbys]

Ok. So say I put the probe in direct light how will I get the probe to stick straight out ? Could I drill a probe size hole in the side wall of the Viv and poke the probe through that ? I was never any good at physics at school. Ha ha

I just bend the cable sticking out, the plastic that covers it is slightly stiff and will generally stay bent if there is not a long length of cable poking out horizontally.

If you or the dragon brush against the protruding probe , it should pretty much spring back to where it's supposed to be.
If it needs support to stay put, the probe is too far from the vertical surface, only needs to be far enough out the probe is not touching any surface , and if it's hanging at a bit of dangle from horizontal it should be fine for the job too.

 

[DiXX]

Ahh thank you guys you have been very helpful as usual 1 day I’ll get it right ha ha

 

[DiXX]

. Ok so something like this. The probe at the back is thermostat and the bottom 1 is temp probe. I know the thermostat has to be angled more. But that sort of position ?

 

[Claudiusx]

Kinda complicating it too much imo lol.

Ask yourself what is the goal here? Do you want your thermostat to control your basking surface temp, or do you want it to control the general temp around the hot side basking area?
Personally I care more about the basking surface temp which is why I'd put its probe where it needs to be to measure that temp. Coopers suggestion of how to place it is what I would do for having a thermostat control basking surface temps.
If you want it to just keep your hot side at a general temp you set it at, then how you have it now is fine.

-Brandon