# Thermostat not going oast 22 degrees



## liam peel (Sep 26, 2011)

So I have a thermostat for my rack, set to 32 degrees now I'm aware it works because I was having g issues before and put the probe in boiling water within seconds in shut off.
Now the probe is in one of the tubs right about where the snake would bask. 
If I rotate the dail it will shut off on 22/23 degrees. Now I have used two different heat sources as I thought it may be as issue with the heat source it was the same thing. 
Now I have a exo terra I fared thermometer and just checked there (right where the probe is) and its 25 degrees so its already hotter than the probe is set to but not hot enough for the ball pythons in there.

I'm really at a loss on what to do I've tried different heat sources, different thermostats, moving the wired, fuses honestly anything you can think of I've probably tried it.

I had an issue earlier in the year where it was the opposite way, it was constantly getting toonhit, up to 40 odd degrees that times.
I've kept snakes for over a decade now and this is the first time I'm having heating issues.


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## ian14 (Jan 2, 2008)

The thermostat is knackered. Potentially putting the probe in boiling water killed it, as its not designed to go over, I think, 35C.
I wonder if this issue is possibly behind your RI outbreak??


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## Malc (Oct 27, 2009)

As far as I know none of the reptile thermostats use digital one wire sensors as probes. They use a thermistor, a resistor that has its resistance changed by temperature, the higher the temperature the higher the resistance. This resistance value is used in a comparator circuit, either using discrete components such as Op-amps or as part of an analogue to digital conversion done by a microcontroller. The problem comes as any damage to the cable can increase or decrease the resistance and thus give incorrect results. Reading what you have stated I would agree with Ian that the stat appears to have a fault.


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## liam peel (Sep 26, 2011)

So I put it in boiling water to see if it was faulty because it wasn't shutting off other than at 22 degrees despite the temperature inside the tub being higher.

I've never had an ri outbreak thankfully. I've now doubled up the heat wire just in the chance that it wasn't able to heat up correctly with only 1 wire, I'm aware this doesn't resolve the issue with the thermostat but gonna keep an eye on it tomorrow and see how it goes. A lot of my snakes, well all but 1 out of 8 have now went off food (a few are hit and miss anyway even in "perfect" conditions) but usually atleast 6/8 eat every week, now its the total opposite.

Naturally when I find out I will post about it.

Thanks for the advice guys.


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## Malc (Oct 27, 2009)

I get the impression you are using a heat cable in a rack - I've never had any success with these cables. Swap it out for heat mats and get a couple of mat stats to run no more than 4 mats in parallel. You can use a 4 way 1m extension cable to run them from the one output. Place the probe on one of the panels of one of the middle mats so it doesn't prevent you placing the tub flat against the mat. You'll still get a slight variation between the four, but they should still be within a degree or so of each other on the surface. The thing is that when using a rack system for tropical species ideally the room in which the rack is housed should be heated to 26-28c 24/7 so that the mats are only providing a localised heatspot.

I've had to switch all my heating from CHEs to Mats in 9 vivs to reduce the consumption of electric. Its not ideal, and given the rooms in which the vivs are in fall to 18c at night the snakes have become less active, but all but one are still eating as the mats still warm them up to 33c.


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## liam peel (Sep 26, 2011)

Malc said:


> I get the impression you are using a heat cable in a rack - I've never had any success with these cables. Swap it out for heat mats and get a couple of mat stats to run no more than 4 mats in parallel. You can use a 4 way 1m extension cable to run them from the one output. Place the probe on one of the panels of one of the middle mats so it doesn't prevent you placing the tub flat against the mat. You'll still get a slight variation between the four, but they should still be within a degree or so of each other on the surface. The thing is that when using a rack system for tropical species ideally the room in which the rack is housed should be heated to 26-28c 24/7 so that the mats are only providing a localised heatspot.
> 
> I've had to switch all my heating from CHEs to Mats in 9 vivs to reduce the consumption of electric. Its not ideal, and given the rooms in which the vivs are in fall to 18c at night the snakes have become less active, but all but one are still eating as the mats still warm them up to 33c.


Yeah using heat wire, well two now.

I have used them for a while now and only ran into problems last year, ironicly when we stopped using the heating due to the rising gas prices, now my bedroom the radiator has been turned off for years now hence why I purchased another heat cable to double it up.

When I did though inused 1 cable for the top 4 and another cable fir the bottom 4, top 4 over heat bottom 4 not heating up enough, no middle ground 10 degrees too hot or too cold.

I have thought about just purchasing mats instead but genuinely thought it could be the thermostat thats the issue because of what I've mentioned above, not shutting off ect not getting warm enough but the thermostat would have shut off thinking it was


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## Malc (Oct 27, 2009)

liam peel said:


> Yeah using heat wire, well two now.
> 
> I have used them for a while now and only ran into problems last year, ironicly when we stopped using the heating due to the rising gas prices, now my bedroom the radiator has been turned off for years now hence why I purchased another heat cable to double it up.
> 
> ...


Testing a stat can be done by using cold or hot water in a glass (not advisable to dunk the probe into water !). Plug a light into the stats output and stick the probe to the outside of the glass using some tape. Set the stat so that its powering the lamp and then add some warm water (50c is fine - doesn't need to be boiling) to the glass. When the stat switches off start adding small amounts of cold water, taking a temperature reading of the water as you go. Ideally when the water temperature hits the set point of the stat, depending on the stats design the lamp will either come on dimly, start pulsing , or come on solid. Add a little more water to see if the lamp brightens, stays on due to longer pulses or remains on. Repeat until the lamp is constantly lit, and then repeat the process using hot water to slowly raise the temperature and reverse the process. IF this normal operation fails then the stat is faulty. If it works fine then the issue is the cables (like I said I've never had any success using them, mainly as they don't give an even spread of heat, and the swing when using a normal on/off stat was too great resulting in a hot side that was either too warm or too cool. You do get better results using a dimmer or pulse proportional stat as they have a much more precise means of control, allowing you to dial in the sweet set point easier.


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## MrsTim (Aug 20, 2012)

I'm not sure what kind of thermostat you have - but this has happened to me once, and the thermostat was faulty, I was told by either the manufacturer, or the seller at the time that this was a safety feature- when the thermostat is broken, it is designed to cut out at low temperature, so as not to cause overheating.


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