My rack temps are driving me NUTS...please help!

Hi,

My rack is a 4 high 41 qrt herpenclosure rack. My temps are driving me nuts as I can't get them to where I want them. Not even close.

I taped the herpstat probe directly to the 3inch heat tape. I put 3 different digital thermometers in the tub for testing. Here were my results:

- ambient room temp was 72
- herpstat thermostat was set to 100
- digi thermometer taped directly to heat tape 94
- hot side 80
- cool side 76

What the heck is going on? Is there really a 14 degree difference from the temp probe taped on the heat tape and the temp probe taped to the bottom of the tub on the hot side. What is that 1inch of space??

How high can i crank the thermostat up to make up for this? How hot can i let the heat tape get to? I seems I would have to crank my thermostat up another 12 degrees (112) to get it to the 92 on the hot side.

Any help would be appreciated.

Nothing abnormal there there will always be a difference between the temp in the tub and the temp measurement taking directly from the heat tape.

What you need to do is play around with your t-stat until the temp measured in the tub preferably with a temp gun (as they give the most accurate reading) reach the desired temps.

Depending on the t-stat, tubs, substrate, heat source it can vary greatly.

Before committing yourself to craziness consider this: all thermometers and thermostats (unless you are spending mega dollars) have error margins. Check the package of your equipment. Cheap thermometers are likely to be out of calibration with no way to adjust them. If each piece of equipment is off by two degrees in opposite directions then you have a 4 degree error right there. Also, how cold is the room temp (outside the rack). This plays a course in how hard the heat tape has to work. Some say 3" is fine for a hot spot but I disagree. I only use a 3" strip for my 12 quart tubs and a double 3" strip for the bigger tubs. Also, I only use the 10w 3" tape because the 6 watt seems a bit weak in the winter. I see variation in my rack as do you. I set my herpstat to 97 F. The thermometer taped to the heat tape always reads 96.6 F +/- a tenth of a degree. I have two thermometers in each tub. My warmest hotspot is 94 F and my coolest 90 F the cool side varies with the room temps but I never let it go cooler than 75 F. When the cool side drops I drag out the space heater. I think you should first test your equipment. Tape all the thermometers to the heat tape. Note each thermometers error margin. Unless you have a faulty herpstat (unlikely) or probe your tape will be the temp you have set on your herpstat. Based on what I have seen, you loose from 4-7 degrees of heat from the tape to the bottom of the tub (more if ambient is cooler). Were me, I would add another strip of 3" 10w to each shelf but many will say this is unnecessary.

Quote:

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Originally Posted by Ladybugzcrunch

Before committing yourself to craziness consider this: all thermometers and thermostats (unless you are spending mega dollars) have error margins. Check the package of your equipment. Cheap thermometers are likely to be out of calibration with no way to adjust them. If each piece of equipment is off by two degrees in opposite directions then you have a 4 degree error right there. Also, how cold is the room temp (outside the rack). This plays a course in how hard the heat tape has to work. Some say 3" is fine for a hot spot but I disagree. I only use a 3" strip for my 12 quart tubs and a double 3" strip for the bigger tubs. Also, I only use the 10w 3" tape because the 6 watt seems a bit weak in the winter. I see variation in my rack as do you. I set my herpstat to 97 F. The thermometer taped to the heat tape always reads 96.6 F +/- a tenth of a degree. I have two thermometers in each tub. My warmest hotspot is 94 F and my coolest 90 F the cool side varies with the room temps but I never let it go cooler than 75 F. When the cool side drops I drag out the space heater. I think you should first test your equipment. Tape all the thermometers to the heat tape. Note each thermometers error margin. Unless you have a faulty herpstat (unlikely) or probe your tape will be the temp you have set on your herpstat. Based on what I have seen, you loose from 4-7 degrees of heat from the tape to the bottom of the tub (more if ambient is cooler). Were me, I would add another strip of 3" 10w to each shelf but many will say this is unnecessary.

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I forgot to add that i have 2 strips of 3inch heat tape running side by side on the hot side. Both individually wired. My ambient room temp is 70-72.

My flexwatt is at 107 to get 89 :)

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Originally Posted by Simplex

My flexwatt is at 107 to get 89 :)

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So I'm not alone! Thanks. However, my new concern is that this is because my ambient room temp is low. If the ambient room temp raises and I have my thermostat set at 105 - 110, will the thermostat self regulate itself to "normal" temps and now my snakes are in the low 100's....damn hobbies.

There will allways be a gap between uth and tub. My room is heated to 78 and i still have a 17 degree gap in a tightly closed rack

Racks are not very efficient heating wise. Aside from the mentioned thermometer issues (I have 15 herpstat (probes and all of them are with in 0.3ºF or each other and yes my business owns a very good accurate thermometer and no I would not recommend buying one...) I would trust the herpstat probe but a simple check is to swap them and see if they are reading the same variation.

Racks really want ambient air temps to be quite warm typically 80ºF is what most use. There are strategies to over come this but it is complicated. I have done so because my snake room has seaweed bags in the walls and heating the room is not practice until I tear out the walls inside and out...

I run hot and cool side tape (4 inch and 17 inch) and a insulated rack with T-stats on both hot and cool as well as top set and bottom set. (4 probes) to keep things stable and correct. It is far easier to stabilize room temps and then set a mid point top to bottom.

Please someone explain to me why you are putting the probe directlly on heat sources? Is this so ya dont have to use a vacant tub? I just dont get it. Onall my racks i have the probe in a tub. I keep 90 hot side and 85 cool side. I just dont get why you would play a guessing game by putting it on the heat source. You want to detect temps where the animal is living. Now i do agree the most important thing is ambient room temps. My snake rooms stay at 80 to 83. About 12 years ago i was having issues that were due to dead spots in the old flexwatt. But i havent had problems in it recentlly. Different racks need higher ambient temps to be stable.depending on how they are set up. Believe it or not my melamine racks are more reliable then my visions or freedom breeders in the heat dept.

Quote:

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Originally Posted by snake lab

Please someone explain to me why you are putting the probe directlly on heat sources? Is this so ya dont have to use a vacant tub? I just dont get it. Onall my racks i have the probe in a tub. I keep 90 hot side and 85 cool side. I just dont get why you would play a guessing game by putting it on the heat source. You want to detect temps where the animal is living. Now i do agree the most important thing is ambient room temps. My snake rooms stay at 80 to 83. About 12 years ago i was having issues that were due to dead spots in the old flexwatt. But i havent had problems in it recentlly. Different racks need higher ambient temps to be stable.depending on how they are set up. Believe it or not my melamine racks are more reliable then my visions or freedom breeders in the heat dept.

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For safety precautions. This way you know what the heat tapes temps are exactly. Putting the probe in a tub will only cause the heat tape to work harder and get hotter. If that probe were to move, the snakes are at risk of being burned.

I dont use Herpstat for my racks but Johnson. All are set at either 89,90,91 and i get those temps exactly in room temp 80-81. When the t-stat kicks on the heat tape does read 100f+ but inside never goes above the set temps.


On the herpstat check the settings on herpstat to be sure its working to its full potential.