Accuracy of Ranco Digital Controllers
- Thread starter Bryan
- Start date
Puffer Daddy
Premium Member
What perfect timing...
I got one as well...but I lost my directions. By chance, can someone tell me how to set it up to cut off heaters at 80 and turn a fan on at 83?...sorry, my wife can certianly vouch for me losing things...
I got one as well...but I lost my directions. By chance, can someone tell me how to set it up to cut off heaters at 80 and turn a fan on at 83?...sorry, my wife can certianly vouch for me losing things...
Puffer Daddy: Press the set button until you get S1 and the temp is flashing. Set this to the temp you want the heater to come on. Press set again, and set the differential (I dont know what this does so I set it to 1), press set to choose between C1 (cooling mode) or H1 (heating mode). Do the same for S2 except you will choose either C2 or H2.
HTH
BTW if anyone can tell me what the differential is for I would appreciate it
HTH
BTW if anyone can tell me what the differential is for I would appreciate it
pjf
Premium Member
Glass Thermometer Measurements
Glass Thermometer Measurements
Unlike many aquarium controllers, the Ranco ETC cannot be calibrated if it drifts. How accurate is it? If you own a Ranco and a glass thermometer, I’d appreciate your posting the following:
1. Temperature as displayed by your Ranco
2. Temperature as measured by your glass thermometer
3. Number of month or years that you have used your Ranco
Thanks!
Glass Thermometer Measurements
Unlike many aquarium controllers, the Ranco ETC cannot be calibrated if it drifts. How accurate is it? If you own a Ranco and a glass thermometer, I’d appreciate your posting the following:
1. Temperature as displayed by your Ranco
2. Temperature as measured by your glass thermometer
3. Number of month or years that you have used your Ranco
Thanks!
purplereef
Active member
How do you adjust the differential?
miatawnt2b
New member
Ranco controllers are going to be dead on. They are industrial controllers used to control things like walk-in coolers at blood banks/hospitals and such where the temp must be super accurate. Don't confuse one of these controllers with its aquarium counterpart you can pick up for $10 nor your house thermostat.
-J
-J
BeanAnimal
Premium Member
They can be +/- 1 degree according to the specs. So if you put 100 of them in the same environemnt you should expect to see a rang of about 3 degrees maximum between the highest and lowest reading. The specs and reality are two different things. In most cases the RANCOS have a much tighter tolerance than the published specs! On average (in reality) you would be looking at 1 to 1.5 degrees max difference between the highest and lowest readings out of a large sample.
This is MORE than accurate enough for a fish tank and much more accurate than your typical "floater" or low grade thermometer.
Remember folks we are attempting to keep our tanks in an acceptable RANGE that is fairly wide, not at a specific dead nuts temperature.
The RANCO controller is very dependable and that is what is important.
This is MORE than accurate enough for a fish tank and much more accurate than your typical "floater" or low grade thermometer.
Remember folks we are attempting to keep our tanks in an acceptable RANGE that is fairly wide, not at a specific dead nuts temperature.
The RANCO controller is very dependable and that is what is important.
pjf
Premium Member
I’ve never used the Ranco ETC but the differential is usually the point at which a heater (or chiller) will be activated. For example, if your set point is 75-degrees and your differential is 5-degrees, then your heater will switch ON at 70-degrees (= 75 - 5) and switch OFF upon reaching the set point.
Are there any links to Ranco ETC specifications regarding its accuracy? This is becoming important as many aquarists are relying on their controller as a thermometer.
Are there any links to Ranco ETC specifications regarding its accuracy? This is becoming important as many aquarists are relying on their controller as a thermometer.
BeanAnimal
Premium Member
PJF why do you insist on beating this horse when you already know the answers?
1) Yes the "differential" or "Hysteresis" determines the range between the thermostats ON and OFF settings.
2) I already told you what the specifications were. Again, +/- 1 Degree F. That means you either do not read or want to discredit me by showing peopke that you have ignored what I posted. Good grief.
3) It is not AT ALL important. Once again, we are shooting for a temperature within a broad range, not an exact. It simply does not matter. If your thermometer or controller says 77 and the tank is actually 78.2 who cares. If you run on the ragged edge at a normal temp around 84 degrees, then you may be more concerned, but your time would be better spent finding a way to run at a slightly lower temperature than it would be obsessing about the number of significant digits that your thermometer can be calibrated to.
1) Yes the "differential" or "Hysteresis" determines the range between the thermostats ON and OFF settings.
2) I already told you what the specifications were. Again, +/- 1 Degree F. That means you either do not read or want to discredit me by showing peopke that you have ignored what I posted. Good grief.
3) It is not AT ALL important. Once again, we are shooting for a temperature within a broad range, not an exact. It simply does not matter. If your thermometer or controller says 77 and the tank is actually 78.2 who cares. If you run on the ragged edge at a normal temp around 84 degrees, then you may be more concerned, but your time would be better spent finding a way to run at a slightly lower temperature than it would be obsessing about the number of significant digits that your thermometer can be calibrated to.
BeanAnimal
Premium Member
NO PJF, no links. Your obsession with "published links" baffles me. In this case why does it matter? You can certainly call them and speak to an engineer.
But lets use some basic logic here.
If the minimum hysteresis is +/- 1 degree F. Then any amount of precision beyond 1 F is pretty much useless (esp for our purposes). The unit only displays full degrees, not tenths.
We can of course show that higher accuracy does have some effect on the display, but how much?
Lets assume it rounds for the display (the other option would be truncation). So if the true temperature is 77. 8 and the precision was +/- 1 degree then the display could read 77, 78 or 79 degrees. At no point will the display ever read more than about 1.5 degrees different than the actual temperature. Well within the acceptable range of precision. In the real world that range is likely less than a degree.
Here is the important part PJF!
If the precision of the unit was .5 degrees, then the display would still show 2 possible temperatures for some readings!
If the precision of the unit was .001 degrees, then the display WOULD STILL SHOW 2 possible temperatures for some readings!
Making the sensor several times more accurate only makes the display slightly more accurate. At best, even with a +/- .001 accuracy, you can only be confident that that display is within .5 degrees!
With a +/- .5 degree precision, the display will be within about .75 degrees of the actual temperature worst case! In most cases it will be within less than .25 degrees.
With a +/- 1 degree precision, the display will be within about 1.49 degrees of the actual temperature worst case! In most cases it will be within less than a degree.
We can carry out the same exercise for truncated displays as well.
If you are having trouble wrapping your head around this, I can build you a very basic spreadsheet to demonstrate the points being made.
The base point remains the same. It just does not matter. The reliability is important aspect. If your concerned about the real world difference between a degree F, then you may want to rethink your understanding of tank temperature as it relates to the real world. We are not conducting a precision lab experiment that requires heat calcs to be accurate.
But lets use some basic logic here.
If the minimum hysteresis is +/- 1 degree F. Then any amount of precision beyond 1 F is pretty much useless (esp for our purposes). The unit only displays full degrees, not tenths.
We can of course show that higher accuracy does have some effect on the display, but how much?
Lets assume it rounds for the display (the other option would be truncation). So if the true temperature is 77. 8 and the precision was +/- 1 degree then the display could read 77, 78 or 79 degrees. At no point will the display ever read more than about 1.5 degrees different than the actual temperature. Well within the acceptable range of precision. In the real world that range is likely less than a degree.
Here is the important part PJF!
If the precision of the unit was .5 degrees, then the display would still show 2 possible temperatures for some readings!
If the precision of the unit was .001 degrees, then the display WOULD STILL SHOW 2 possible temperatures for some readings!
Making the sensor several times more accurate only makes the display slightly more accurate. At best, even with a +/- .001 accuracy, you can only be confident that that display is within .5 degrees!
With a +/- .5 degree precision, the display will be within about .75 degrees of the actual temperature worst case! In most cases it will be within less than .25 degrees.
With a +/- 1 degree precision, the display will be within about 1.49 degrees of the actual temperature worst case! In most cases it will be within less than a degree.
We can carry out the same exercise for truncated displays as well.
If you are having trouble wrapping your head around this, I can build you a very basic spreadsheet to demonstrate the points being made.
The base point remains the same. It just does not matter. The reliability is important aspect. If your concerned about the real world difference between a degree F, then you may want to rethink your understanding of tank temperature as it relates to the real world. We are not conducting a precision lab experiment that requires heat calcs to be accurate.
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Here ya go pretty straight forward.
http://www.honeyrunapiaries.com/store/pdf/ranco_etc_instructions.pdf
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