2 different temp readings

ok so i just got this ranco thermostat in the mail today and got it all wired up without too much of a problem. I put the thermostat probe in the tank right next to the accurite thermometer probe but now the accurite readings are about 6 degrees cooler than the ranco. My thermostat is telling me that the temps are at 93°F while the thermometer is telling me 87°F. The temps are fluctuating a bit as well since I have the differential temperature on the thermostat set to give or take 5°F. So now as i look over at the thermometer it is telling me 85°F on the hot side!! I don't know which reading to go by or what to do. Please, any help would be greatly appriciated.

ok i can relate i just picked up a ranco to run my backup rack for a friend having issues with 2 many snakes not enough racks. Do you have any other temp probes at home. Second from recent personal experience do you have the temp probe sitting on your heat. Second the accurite takes ambient temp and the probe from you thermostat if placed against the heat source will read hotter due to the fact that it is picking up surface temps. Do you have a temp gun to check your temps for surface temp.

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Originally Posted by shadi11

ok i can relate i just picked up a ranco to run my backup rack for a friend having issues with 2 many snakes not enough racks. Do you have any other temp probes at home. Second from recent personal experience do you have the temp probe sitting on your heat. Second the accurite takes ambient temp and the probe from you thermostat if placed against the heat source will read hotter due to the fact that it is picking up surface temps. Do you have a temp gun to check your temps for surface temp.

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I have a UTH stuck under the tank but I stuck it on after I got the ranco so i couldn't place the probe in between the glass and the UTH. I just have the thermostat probe sitting under the substrate inside the tank. Same goes for the accurite probe. I don't have a temp gun either. Maybe I should get one...

Ok... use foil tape and tape the STAT probe under the UTH around the center. Then put your thermometer probe under the substrate over the UTH inside the cage. There will be a difference between the stat reading and the acurite reading, but just set the stat until your acurite/temp gun reads what you want.

i have mine taped down to the bottom of the inside of the tank. I really don't have any problem with this setup. I have noticed that my accurite temp probe is usually off a couple of degrees from my temp gun but may i suggest setting your differential for temp a little tighter it may kick on and off alot but it will hold a closer temp. I set mine at 3 degrees and you can go as tight as 1 degree according to my directions.if you have any questions on programing just re post them i will help as much as possible

Hmm, I would suggest changing that. ANY tape inside the enclosure = BAD. It works to tape the stat probe to the underside of the UTH and set the thermometer probe under the warm side hide substrate, using the hide to hold it in place.

this coming from an hvac specialist. You will get extreme heat under the tank due to the lack of air circulation directly under the tank. i have checked these temps just now to find that they are 10 degrees hotter under the tank than inside the tank. But if you don't want to tape the probe inside the tank then i have several ways to perminately attach them. I you are using a substrate such as wood chips(i use newpaper) the temp may be even greater due to the insulation factors of the wood. i would say you are right with the tape but i use medical tape to prevent any possible toxic problem in the tank.

I have 3 ranco's in my incubator. One for normal operation at 89 degrees, one that kicks on if the temp drops below 88 degrees, and a third that turns the whole system down if temps reach 91 degrees. I keep them all at 1 degree differential. The temp readings on them all were pretty much dead on with each other and when I stuck a calibrated thermal couple in it came up the same. From this experiment I would say the rancos are pretty accurate. If you can safely attach it to the top of the glass in the bottom of the tank over the heat mat, I would not be afraid to believe the setting on the ranco. Make sure it is firmly pressed against the glass though.

One problem I do have with the ranco is the relays recommended wiring method. If this relay fails it will more than likely fail in its normal state which is closed! This will set the heat element full on unregulated. It may be better to use the Normally open contact and set the ranco to cooling mode. This way when the temp drops below a certain point the ranco will pick up and start the heating element. When your given temp is exceded the relay will drop out and stop powering the heating element.

i have a helix and the same set up as you. try to think of the therm number as like points or sumting and not reallie the temp. and then use the temp gun or accurite to get the temp that u want. for example i put my helix on 96"points" to get a temp of 92F. hope this helps