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heyfredyourhat
11/10/2007, 09:48 AM
I searched the threads for a solid answer and havent found one .....So can i run my jagers fully submersed or not?? Will i get shocked or will the heater die??

Big_D
11/10/2007, 09:53 AM
I've got 2 of them and they have both been run submerged for quite some time. From what I was told, the ones that have a water line marked on them and are marked as non-submersible were made that way due to the UL listing, but they are fully submersible.



Big D

heyfredyourhat
11/10/2007, 10:07 AM
Thats what i read, and i wasnt too sure if the ppl using the submerged ones had the "older" models or not. I will sink them and see what happens!

pjf
11/10/2007, 12:52 PM
Per the Eheim North American website (http://www.eheim.com/jager.htm), the Jager heaters are "fully submersible."

I submerse my Jager heaters and have not had a problem. At one point I tried keeping the top of the heater out of the water per the old instructions and had a 5-degree temperature inaccuracy. I forgot whether this kept the water too cold or too hot.

I like the Eheim Jager heaters because they can be recalibrated if the thermostat drifts. I have a foot-long liquid-in-glass thermometer just for calibration of my temperature controller and Jager heaters.

BeanAnimal
11/10/2007, 01:07 PM
PJF if you ARE running a temperature controller then there WOULD NOT be a 5-degree inaccuracy and the function of the internal thermostat would be irrelevant. The controller takes care of the temperature, not the heater.

To the OP:
It a much better idea to run the heaters with the tops dry and use them on a temperature controller. You should be using a reliable controller no matter what!

Run them in the intake compartment of your sump so that they can not run dry. Place the controllers probe slightly upstream of the heaters.

If only the body is under water then there is no chance of leaking and shorting out.

Setting the heaters thermostats to a failsafe temperature will add a failsafe to teh controllers operation.

pjf
11/10/2007, 02:07 PM
I calibrated my Jager heater with the top above the water and without the controller when I discovered the temperature inaccuracy. Since then, I've calibrated the heaters by using fully submerged readings.

BeanAnimal
11/11/2007, 08:19 AM
The point is that it does not matter if they are "calibrated" or not. The temperature controller is the determining factor. The heaters thermostats only act as a failsafe. Calibration of the internal thermostats is pointless. There is no "temperature drift" due to the heaters. The only "drift" would be due to the hysteresis of the controller. With a RANCO that can be set to as little as 1 degree F.

pjf
11/11/2007, 09:41 AM
A heater's thermostat can keep the tank from overheating when the controller fails. When my controller's probe accidentally fell out of the tank, the thermostatic heater kept the tank from overheating.

I depend on the heater's thermostat to backup my controller. The Jager is one of the few aquarium heaters that can be recalibrated. I have had to recalibrate both my controller and my heaters with a liquid-in-glass thermometer.

The drift may be as little as a few tenths of a degree every few months but it is there. Perhaps drift is more noticeable in my system because both my controller and foot-long thermometer display to the tenth of a degree. The heaters, both Jager and others, can drift by 5 degrees over the course of a year.

When the Jager heater is completely submerged, its thermostat will measure the temperature differently than when its top is above the water line. So it should be mounted with consistency.

BeanAnimal
11/11/2007, 10:08 AM
A heater's thermostat can keep the tank from overheating when the controller fails. Yes PJF that is the idea of using a controller and then using the on board thermostats as failsafes. I clearly stated that above and have clearly stated that dozens of times in dozens of threads.

Please don't act like you are teaching me something when it is obvious that I already understand the concept. It is more than a little condescending and I tire of it.

Again, the point is why bother calibrating it. You simply let the tank come to temperature and then turn the dial on the heater until it clicks off. It is then set as a failsafe. If it drifts over time then you do the same thing to "recalibrate" it. There is no need to set up a laboratory experiment to fine tune the heater.

Secondly, who are you trying to fool here?

1) A RANCO can not be field calibrated. Is that what you are running?

2) Niether the RANCO or the Ebos thermostats are accurate to within a 10th of a degree. The RANCO is +/- at least 1.5 degrees. The JOHNSON and LOVE controllers are similar. Both mechanical and solid state thermostats have hysteresis built in. This may be as much as 5 degrees. Some are adjustable, some are not. Most of the thermocouple type probes that are used with PLCs, aquarium controllers homebrew projects are not accurate to more than a degree or so. If you are using a Finnex or Won Bros, they are even worse (from both an accuracy and a reliability standpoint).

3) There is NO NEED to calibrate an aquarium thermostat to any real degree of accuracy. Ballpark targets are just fine. The idea is stability not accuracy. There is even some debate as to the real benefit of stability. The natural reef swings several degrees over the course of a day.

Again, if you ARE running a controller, then you gain nothing by matching the dial on the heater to the actual temperature it cuts off at.

If you are worried about a few 1/10ths of a degree of drift then you are worried about something that is lost in the significant digits with regard to the overall error of the system.

pjf
11/11/2007, 11:16 AM
The Medusa HC-150 controller that I use displays to a tenth of a degree Fahrenheit and its readings usually correspond to my liquid-in-glass thermometer to a tenth of a degree. I've only had to calibrate it twice in two years.

It turns on the heat when the temperature drops 0.6 degrees below the set point and turns it off 0.4 degrees above the set point. The temperature is stable within that range unless there is a temperature problem with the room. My Jager heater is set two degrees higher and needs calibration more often due to its greater drift.

The thermometer that I use is manufactured by Miller & Weber. There is a review of it on Reef Central.

Many aquarium thermostats cannot be field-calibrated but if you have one that can be calibrated, then you should do so. Otherwise, you would not know what temperatures your thermostats are truly set to.

BeanAnimal
11/11/2007, 12:13 PM
Yes the Medusa is a nice unit by many accounts. It is specified with a +/- .2 degree accuracy. Heat on -.8 degrees below the set point and heat off +.4 degrees above the set point. That is 1.2 degress of hysteresis.

Once again the point IS and WAS that there is no need to calibrate the heaters. The temperature controller is the key component. As long as the heaters thermostats are manually set to just above the normal operating range then all is good.

The second point was that there is no need to be that accurate with regard to temperature. Error within a few degrees is fine. I don't fault you for being accurate, I just do not see a need for it.

I am sure that the Miller thermometer is as good as the reviews for it. Nobody said it wasn't.

fastcar01
11/11/2007, 12:18 PM
How do you calibrate the Jagers? I also run mine with the line under water for years, no problem!

pjf
11/11/2007, 12:59 PM
The instructions are near the bottom of this webpage: http://www.boroniaaquarium.com.au/newsletter/cms_files/Jager%20heater.pdf?NewsletterSession=7c5a8ab1545a1745e6514e6d836edb6f. You may want to use a screwdriver to pry up the blue button.

pjf
11/11/2007, 01:15 PM
<a href=showthread.php?s=&postid=11160223#post11160223 target=_blank>Originally posted</a> by BeanAnimal
Secondly, who are you trying to fool here?

1) A RANCO can not be field calibrated. Is that what you are running?

2) Niether the RANCO or the Ebos thermostats are accurate to within a 10th of a degree. The RANCO is +/- at least 1.5 degrees. The JOHNSON and LOVE controllers are similar. Both mechanical and solid state thermostats have hysteresis built in. This may be as much as 5 degrees. Some are adjustable, some are not. Most of the thermocouple type probes that are used with PLCs, aquarium controllers homebrew projects are not accurate to more than a degree or so. If you are using a Finnex or Won Bros, they are even worse (from both an accuracy and a reliability standpoint).

3) There is NO NEED to calibrate an aquarium thermostat to any real degree of accuracy. Ballpark targets are just fine. The idea is stability not accuracy. There is even some debate as to the real benefit of stability. The natural reef swings several degrees over the course of a day.

I do not use the above controllers. But it is not the accuracy of your equipment that is of concern here. It is the accuracy of your posts.
<a href=showthread.php?s=&postid=11146724#post11146724 target=_blank>Originally posted</a> by BeanAnimal
Your lack of understanding of the basic principles here is jaw dropping! I am not sure what else can be said.

BeanAnimal
11/11/2007, 02:12 PM
I do not use the above controllers. But it is not the accuracy of your equipment that is of concern here. It is the accuracy of your posts.

Trouble with context PJF? You posted that nonsense hours after my reply recognizing that you use a MEDUSA and reiterating my points in that context. If you read you would have also noticed that I pointed out that the MEDUSA is a nice unit. Ohh wait you don't care about context, your intent was to try and discredit me with rhetoric.

Where does that leave us? Well as usual instead of responding to the POINTS BEING MADE you have posted a diversion because you are unable to refute the points being made.

But back to the point and your comments: Please show me where I am not accurate? You can't! You have an affinity for condescension and ignoring the true points being made.

You have taken a comment from another thread. A thread where you have clearly demonstrated a lack of understanding. You have done so why in this thread? Does the comment somehow make my remarks wrong? Of course it doesn't. Not here or in the other thread.

So what are the key points I was trying to make?

1) There is no need to calibrate a heater if it is being operated by a temperature controller.

2) There is no need to be dead nuts accurate with aquarium temperature. The temperature on a reef rises and falls daily and varies over a fairly broad range. As long as we are within that very broad range we are ok. The end of the world is not going to come if your controller reads 78 degrees and the water is actually 76.6 degrees.

3) Even with a very accurate unit, the hysteresis will still allow a temperature fluctuation of at least a degree or so.

4) There is a good argument to be made for allowing the temperature to rise and fall slightly over the day. It does so in nature.

5) The "drift" of the thermostats in the heaters is not important, nor is the fact that they may read different temperatures when submerged or partly submerged. (It is easy to explain why).

Again, PLEASE show me where I am not accurate!

BeanAnimal
11/11/2007, 02:20 PM
Just another little snippet on YOUR accuracy. Your big on quoting stuff...

SO here PER the HC-150 users manual found at :http://forums.slimdevices.com/showthread.php?t=19976&page=6

The heat and cool set points are set by a single digital adjustment
with a range of 32 to 90 degrees Fahrenheit or 0 to 32 degrees
Celsius. The heater will come on at .8 degrees below set
point and stay on until the temperature rises to .4 degrees above
the set point. The chiller will come on at .8 degrees above the set
point and will stay on until the temperature drops to .4 degrees
below the set point. For example, if the HC-150 is set to 75° F
the chiller will come on when the aquarium heats up to 75.8°F
and turn off when the chiller has cooled the aquarium down to
74.6°F. If the aquarium cools to 74.2°F, the heater will come on
and heat the aquarium up to 75.4°F.

Now didn't you just say:It turns on the heat when the temperature drops 0.6 degrees below the set point and turns it off 0.4 degrees above the set point.


I know it is just .2 degrees... but you were not accurate!

pjf
11/12/2007, 06:16 AM
<a href=showthread.php?s=&postid=11161360#post11161360 target=_blank>Originally posted</a> by BeanAnimal
Again, PLEASE show me where I am not accurate!
<a href=showthread.php?s=&postid=11159746#post11159746 target=_blank>Originally posted</a> by BeanAnimal
The point is that it does not matter if they are "calibrated" or not. The temperature controller is the determining factor. The heaters thermostats only act as a failsafe. Calibration of the internal thermostats is pointless. There is no "temperature drift" due to the heaters. The only "drift" would be due to the hysteresis of the controller. With a RANCO that can be set to as little as 1 degree F.

Drift and hysteresis are two different things. Your controller is not calibrated and you have not measured the amount of its drift. I would check the drift on both your controllers and heaters with a reliable analog thermometer.

<a href=showthread.php?s=&postid=11160223#post11160223 target=_blank>Originally posted</a> by BeanAnimal
3) There is NO NEED to calibrate an aquarium thermostat to any real degree of accuracy. Ballpark targets are just fine. The idea is stability not accuracy.
Many aquarists have had heaters stick in the ON-position. Unless you check, you do not know if you have a failsafe. Stability and accuracy both depend on accurately calibrated thermostats.

BeanAnimal
11/12/2007, 12:18 PM
Drift and hysteresis are two different things. You think? of course they are, nobody said they were not. Again, please show me where my statement is wrong. Notice the quotations around the words "temperature drift" and "drift"? If you read the sentences in context you will notice that I am clearly differentiating between true temperature drift and the hysteresis. You are argueing semantics and have again missed the point in favor of trying to discredit me with an irrelevant tangent.

Your controller is not calibrated and you have not measured the amount of its drift. I would check the drift on both your controllers and heaters with a reliable analog thermometer.The controller runs the heaters, the correlation between the heaters dial and its thermostat setting is not at all relevant in this scenario. Again, if it makes you feel good to calibrate it then be my guest. That does not make my statement wrong. The POINT IS and WAS that the "drift" is pretty irrelevant. So what, my tank is 77.8 degrees and the controller says 77. Next month it may be 77.9 degrees and my controller says 77. In 2 years it may be 78.2 degrees and the controller still says 77. Who cares! The temperature of a reef aquarium is not that critical. In the real world the temperature rises and falls over the days and seasons.

Again, please point out where I am wrong. You can't. If YOU want to be that accurate, nobody is stopping you and that is beside the point I made.

Many aquarists have had heaters stick in the ON-position. You think? Again, please stop trying to give the impression that I do not understand that heaters stick on. I preach the need for a controller and failsafes more than anybody here at RC. I have clearly stated so in this thread and dozens of others.

Unless you check, you do not know if you have a failsafe.Simply and utterly not true. You should be embarassed to even try to argue differently. Bring the tank to temperature and then turn the dial on the thermostat just past where it clicks (mechanical) or stops heating (solid state). You have now set it for failsafe operation. Who cares what the dial in the heater says. A simple physical check once in a while is all that is needed to ensure it is properly set. It takes 1/10 of second to reset if it "drifts".

Furthermore, most heaters can not be calibrated anyway. Following your silly argument, they would be useless as failsafes if they could not be calibrated. You can't have it both ways and it makes your arguement pretty silly doesn't it!

Stability and accuracy both depend on accurately calibrated thermostats. Again, that is nonsense in the scope of our discussion. We are not controlling a temperature critical reaction. We are looking after a reef aquarium that mimics a natural reef. In a natural reef temperature swings are normal. So what if 78.6 degrees is actually 77.2! An non calibrated controller still has the same hysteresis as a calibrated one. So stability is exactly the same. As I mentioned accuracy is not that important. So I ask you once again PJF, please show where I am inaccurate. You can't.

pjf
11/12/2007, 07:43 PM
<a href=showthread.php?s=&postid=11167253#post11167253 target=_blank>Originally posted</a> by BeanAnimal
As I mentioned accuracy is not that important. So I ask you once again PJF, please show where I am inaccurate. You can't.
You will have to measure the inaccuracy, drift, and temperature swings of your system with a reliable liquid-in-glass thermometer.

Here is an inexpensive temperature control system:

(1) Thermometer: either the Miller & Weber in the review section of Reef Central or the Tropic Marin (http://www.tropic-marin.com/web/english/produkte/thermo.htm).

(2) Two Eheim Jager heaters: The total wattage should be about 2 watts for each gallon. If you have a 100-gallon system, get two 100-watt heaters.

Calibrate both heaters with your thermometer. If one small heater fails in the ON-position, it will be less likely to kill your livestock than if you have one large heater.

The advantages of this system are:

(1) Inexpensive
(2) Can be calibrated
(3) Can accurately measurement drift and temperature swings
(4) Less likely to quickly overheat or quickly underheat your tank in case of single heater failure.

BeanAnimal
11/13/2007, 04:37 AM
My point has not changed and you have not shown me to be wrong. I made a simple comment when I entered this thread. It was: [sic] The differences between submerged and partially submerged thermostat operation do not matter if the heaters are being operated by a temperature controller.Why do you insist on tying to continue this debate? I would be dishonest if I told you that I did not find this amusing.

So back to the point:
Calibration - There is simply no need to go through the trouble even in the scenario you have posted above. "Calibration" of the heater only means that the DIAL reads correctly. It has nothing to do with the physical operation of the heater itself. The deeper you dig the more silly this gets.

Lets visit your points:
(1) Inexpensive - Not as inexpensive as skipping the thermometer altogether. It is not needed. It certainly does not hurt but you gain little from using it. Again, beside the point. If it makes you feel better then go for it! I have NO PROBLEM with somebody wanting to know the exact temperature of their tank. the POINT is that it is not at all important. It is a feel good kind of thing.

(2) Can be calibrated - As mentioned several times, it is fairly pointless to go through the trouble. It hurts nothing but temperature is not aht critical in our systems. Calibration ONLY matches the thermostat markings to the actual shut off temperature of the heatar and has nothing to do with the heaters physical operation. If the heater turns off at 77 degrees and the dial say 102, who cares. The rest of the world monitors their thermometer NOT their heaters dial. DRIFT is taken care of in the same fashion (by looking at the thermometer).

(3) Can accurately measurement drift and temperatrue swings. - Again fairly pointless in the scope of our systems. The calibration HAS NOTHING to do with temperature swings. Measuring them has to do with the thermometer or other data logging device. Drift would be measured and compensated for by the same process without EVER having to "recalibrate" the dial on the heater. As also mentioned, the natural reef swings in temperature over the day and the season. We are not trying to stick our tanks and a static temperature within 1/10 of a degree, let alone 5-7 degrees.

Lets put this another way. IF you are using a thermometer to monitor the tanks temperature (you should be using something to ensure you are in the ballpark) you do not need to calibrate. Drift is a physical property of the thermostat. All calibration does is allow one to match the heaters thermostat dial to the thermometer. You can as easily set the heaters thermostat by looking at the same thermometer. How in the world do you think those with "non calibrateable" units do it? If it is important for YOU to see that the dial matches the thermometer, then go for it. Just don't try and tell teh rest of us that it makes a difference in the operation of the heater or the end result.

(4) Less likely to quickly overheat or quickly underheat your tank in case of single heater failure. - You think? Once again PJF, you are posting something that I preach daily here at RC. Several small heaters are safer than one larger heater. This has abosoletly nothing to do with calibration.

Can we move on now?

mhurley
11/13/2007, 07:21 AM
:rolleyes:

clevengergl
11/13/2007, 01:08 PM
Well, I didn't learn JACK about heaters in this thread but I did come to a pretty solid conclusion that I don't want to be an engineer...

Seriously, guys, sounds like you two need to take this offline and whip out the measuring tape. Unless, of course, you have something a little more productive and less trivial to post regarding this topic???

Gary

BeanAnimal
11/13/2007, 02:40 PM
Gary,

I am not (and will never be) an engineer but I did sleep at a Holiday Inn last night!

There is certainly a lot to be learned in this thread. Let me try to boil it down in a somewhat wordy fashion.

Our systems are designed to mimic certain aspects of the ocean. Part of the life support of our systems is temperature control equipment.

There is not a specific temperature that is important but rather a range of acceptable temperatures. That range is in the 70-86 degree Fahrenheit neighborhood with 75-82 F. being the target for most reefers.

The temperature on a given reef will rise and fall over the day and from season to season. These changes come from tidal movement, sunlight, rain and freshwater sources, seasonal changes, etc. These daily swings can be a degree or so in some areas and as large as 10 or more degrees in other areas. There have been strong arguments made that daily swings in our captive systems are not only acceptable but healthy.

Even if we did not want the temperature to swing it will anyway. There needs to be some wiggle room between the point that a thermostat turns on the heat and where it turns it off at. We call this hysteresis. If there were no hysteresis the heater would click on and of constantly due to tiny changes in temperature right at the setpoint. As shown above, even the very tight tolerances of the MEDUSA controller allow well over a degree of swing! If you use a RANCO or similar it will be closer to 2 Degrees (even with the unit set to 1 degree differential). Again, not a bad thing at all. We are not conducting a laboratory experiment where precise temperature is important.

Calibration as it is discussed here ONLY means adjusting the dial on the heaters thermostat so that it shows the proper number when the heater turns off. It has nothing to do with the way the controller or heater works. In a more complex system that uses multipoint calibration thing may be different. We don't need to go into the details because that is simply not what we have here.

So lets get back to our heaters, remembering that the actual temperature that we keep our tanks at is not all that important as long as it falls within the acceptable range. We should also keep in mind that the natural reefs temperature swings within an average range daily. That range drifts in one direction or the other (hotter each day or colder each day) depending on the season that is coming or going. The hysteresis and drift of our equipment is well within the range of the above. Regular testing of the tank with a thermometer keeps the equipment honest.

So lets talk about those heaters now:

Most hobby heaters are comprised of a resistive heating element and a small bi-metal thermostat. As the temperature changes this metal thermostat expands or contracts and forces the heaters contacts to complete or break the electrical circuit. Each time this happens the contacts spark and a little bit of them is blasted away. The small bi-metal thermostat is also very prone to failure due to metal fatigue. That question is not IF the thermostat and contacts will fail but WHEN. More often than not these contacts fail in the closed position forcing the heater to stay on until YOU the aquarists finds the problem.

Solid state hobby heaters use cheap electronic sensors and either a mechanical relay or a solid state relay to turn the element on and off. The electronics in these heaters are very poorly designed and are made as cheaply as possible. These units may fail ON or OFF depending on their design.

The bottom line is that cheap, reliable and miniature are pretty much mutually exclusive combinations when it comes to mechanics and/or electronics.

You can pretty much only have:
cheap and miniature = NOT reliable
cheap and reliable = NOT miniature
reliable and miniature = NOT cheap

Hobby heaters are miniature and cheap... that leaves them NOT reliable.

So we have to do something to get past the reliability problem. We have two basic choices.

1) Connect the heater(s) to a RELIABLE (read EXPENSIVE) device to control them.

-or-

2) Create a situation where a single unreliable device does not cause a disaster

-or-

3) leverage both case (1) and case (2) to create a fairly failsafe system.

Case 1) We use a reliable controller to operate the heater. We can add some failsafe features by setting the heaters thermostat slightly above the setpoint of the controller. If for any reason the controller itself stick ON, the heaters internal thermostat will turn the heat off. The thermostat will be MUCH more reliable because it is never used. The bi-metal strip and contacts will not show signs of fatigue or wear.

Case 2) We divide the total wattage among several heaters. In this way if a single heater sticks on, the effects to the tank are not as rapid as if a large heater were to stick on. If a single heater fails OFF the others can still maintain tank temperature.

Case 3) We put several heaters on one or more temperature controllers. We get the best of both case 1 and 2.

Lets take an example system that hold 100G of water. 100G of water weighs 833 pounds. It therefore takes 833 BTUs to raise that mass of water 1 degree Fahrenheit.

1 Watt = 3.413 BTUs an hour of heat. So the 500W heater will produce 1706.5 BTUs every hour that it is on. Remember it takes 833 BTUs to raise the 100G tanks temperature by 1 degree Fahrenheit. So in one hour the heater will be able to raise the tank temperature by 1.3 degrees Fahrenheit.

Lets look at a 500W heater in this system that has failed in the ON position. The tank is 78 degrees at 10:00 AM when the heater fails. You get home from work at 6:00 PM. That is 8 hours or 10.33 degrees Fahrenheit! Your tank is now over 88 degrees! You getting close to tank wipe out temperatures!

If we use "Case 3" from above... A controller and (2) 250W heaters instead of (1) 500W heater. We assume that the controller AND a single heater stuck ON (not likely, but possible) then the temperature rise would only have been about 5 degrees F. That tank would only be a little over 83 degrees and your livestock would live to tell the story another day.

As for calibration and lab grade thermometers. If knowing your tanks temperature to a 10th of a degree makes you feel better then you may want to take the advice given by PJF. Your corals and fish don't care one way or the other as long as you are within the ranges listed at the beginning of this post.

oct2274
11/13/2007, 03:32 PM
bean, you crack me up sometimes hehe, always gotta get in a ****ing match........this thread got way out of control lol

radone
11/13/2007, 04:24 PM
BTW
Bean I think you meant Holiday Inn Express :lol:

BeanAnimal
11/13/2007, 04:27 PM
Hey I can't get everything correct. Give me a break!

clevengergl
11/13/2007, 04:34 PM
Thanks Bean! That's exactly the info I was looking for!!! Definitely sounds like the controller and several smaller heaters is the best option. I use a primary, high-powered heater in my 65 and haven't had any problems, but now that I'm setting up my 220 I don't really feel like taking any chances! :-)

BeanAnimal
11/13/2007, 04:40 PM
It only takes one time to become a believer and look for a better way. As a kid I lost a very old piranha to a stuck heater. The water was steaming when I got home.

Your best bet is a RANCO. They are commercial/industrial units and pretty damn reliable (magnitudes better than any hobby equipment). The dedicated aquarium automation controllers have also proven to be fairly reliable if setup proplerly. I would NOT run a heater on an X-10 coupled output or something like the DC-8.

The RANCO can be had for maybe $70 for a single stage and $90 for a dual stage (heat and cool).

You have the math now, so you can figure out how to divide your heaters based on volume. You can also size your heaters based on the ambient room temperature and the desired tank temperature.

Bean

pjf
11/13/2007, 10:05 PM
Here's an excellent forum for comparing controllers: http://www.reefcentral.com/forums/showthread.php?s=&threadid=997688&highlight=controller

You may want to check out temperature controllers that can be calibrated. One of the reasons for buying a controller is to display the temperature of your system. If a controller drifts, as electronic systems are apt to do, then the wrong temperature may be displayed and maintained. If your controller can be calibrated against a thermometer, then you can correct the display.

Good luck!

BeanAnimal
11/14/2007, 07:15 AM
You may want to check out temperature controllers that can be calibrated. One of the reasons for buying a controller is to display the temperature of your system. If a controller drifts, as electronic systems are apt to do, then the wrong temperature may be displayed and maintained. If your controller can be calibrated against a thermometer, then you can correct the display.

Again, we have a very wide temperature range to be comfortable in. Most reputable controllers are accurate within +/- 1.5 degrees. As long as the display is within a fairly wide tolerance, we are just fine :)

RANCO ETC controllers CAN NOT be field calibrated, yet they are used on hundreds of thousands of pieces of equipment and process controllers. They are widely accepted as accurate and reliable. Sure it would be nice if you could field calibrate the displays... but then again they don't really need it. I am more than comfortable with the fact that my RANCOS all read within a degree of each other.