# Eheim Heater calibration issue



## Darkblade48 (Jan 4, 2008)

Didn't you have to push down or something before turning on the newer Eheims?


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## DaveK (Jul 10, 2010)

I think your missing something. 

Actual temp is controlled by turning the blue ring. The red pointer just moved back and fourth a little so you can match the actual temp of the water to the temp on the blue ring. 

If the heater is holding your water at the temp you want and the red pointer can't be adjusted any more, your still ok as far as the water goes.

Here is a link to Eheim's heater instructions (offsite) - https://www.eheim.com/resources/product//485/downloads/11/EHEIM_aquarium_heater_25_-_300_manual.pdf


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## steveo (May 25, 2012)

DaveK said:


> I think your missing something.
> 
> Actual temp is controlled by turning the blue ring. The red pointer just moved back and fourth a little so you can match the actual temp of the water to the temp on the blue ring.
> 
> ...


Yes, I understand that the blue dial is what controls the temp. And yes, I simply am not able to adjust the red pointer dial to agree with the 78 degree marker on the blue dial. Being able to complete this calibration would make any future adjustments much easier. This kind of annoys me, yet I wanted to make sure I wasn't overlooking something prior to following up with any warranty claim.


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## natemcnutty (May 26, 2016)

Mine cannot be properly calibrated either, but I know it is always 2 degrees off. Due to that, I purchased an inkbird controller and just leave the heater at a couple degrees higher than my target temp on the controller.

To me, I saw money that would have been spent on shipping for a warranty claim as a discount on the controller [emoji14]


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## jeffkrol (Jun 5, 2013)

One of 2 I own is unable to be calibrated. Oddly enough it was a warranty replacement straight from Eheim for one that the blue dial broke on. That one, though stuck at 78F at least showed the correct temp..  

To be honest, I am not impressed.


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## Jared Becker (Aug 9, 2018)

OK, guys I know this is an older thread but I've had the same issue where you can't calibrate it far enough. Mine was like 6 degrees off. I just couldn't take it anymore so i took it apart and tried to figure out why it wouldn't go further. I found out that there is a post sticking up under the blue temperature ring that controls the temp. so all i did is lift the tab off the top and there is a black round pin that comes up about an 1/8" and then you can lift the blue temperature ring up and with a pliers i turned the shaft so it was adjusting temp without moving any gears. the tricky part was adjusting in the correct direction. but the tab you take off the top pretty much breaks off because how its made. but you can super glue it back on if you really want. but doing this does NOT effect the waterproofing, the waterproofing is under the post you turn.

Any questions: ask away.


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## PlantedRich (Jul 21, 2010)

I like your attitude on finding the "why" and fixing it! I've given up on chasing the right brand for quality as so many companies are just corporations chasing the max profit.


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## Ben3721 (Jan 20, 2018)

Having taken one apart I agree on popping the tiny black cap off to pop the calibration pin up then rotate the red ring center, then the main dial to what temperature it was actually at and push it back down. Pretty much that black or silver pin for some models separates the gear from the dial harmlessly for a complete range of calibration without breaking the seal.

But here’s why this is pointless. Let’s say you calibrate it to 74 degrees perfectly. Then turn the dial to 70 and it drifts to 68 or turn it to 78 and it ends up being 83. Well at that point you realize the numbers on the dial aren’t accurate to begin with. It’s a rod that presses on a metal plate that warps from heat to trigger it on and off. Expecting a perfect linear change is asking too much.

It’s still a great heater, but trust a higher end thermometer, not the number dial.


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## Jared Becker (Aug 9, 2018)

Ben3721 said:


> Having taken one apart I agree on popping the tiny black cap off to pop the calibration pin up then rotate the red ring center, then the main dial to what temperature it was actually at and push it back down. Pretty much that black or silver pin for some models separates the gear from the dial harmlessly for a complete range of calibration without breaking the seal.
> 
> But here’s why this is pointless. Let’s say you calibrate it to 74 degrees perfectly. Then turn the dial to 70 and it drifts to 68 or turn it to 78 and it ends up being 83. Well at that point you realize the numbers on the dial aren’t accurate to begin with. It’s a rod that presses on a metal plate that warps from heat to trigger it on and off. Expecting a perfect linear change is asking too much.
> 
> It’s still a great heater, but trust a higher end thermometer, not the number dial.




Yea I thought Eheim was a reputable brand which is why I bought it. Won’t make that mistake again.


Sent from my iPhone using Tapatalk


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## lksdrinker (Feb 12, 2014)

Jared Becker said:


> Yea I thought Eheim was a reputable brand which is why I bought it. Won’t make that mistake again.
> 
> 
> Sent from my iPhone using Tapatalk


Its not so much that its not reputable. Its just the nature of how aquarium heaters work make them difficult to be user friendly (at least without costing a fortune for a different technology altogether). In the end, I think a heater that will hold temp correctly within 1-3 deegrees (no matter what number the dial points to) is a winner in my book. As the OP of this thread said, the heater warmed the RO water to 78 degrees which was exactly what was needed.


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## jeffkrol (Jun 5, 2013)

Thermal bi-metal snap switches are old tech:
https://www.drsfostersmith.com/product/prod_display.cfm?pcatid=21333

I've had dirt cheap heaters that weren't as prone to "problems" as my 3 Eheims...
From frozen dials that break to unable to calibate.. 2 out of 3 are "failures"...


In all fairness I've had one out of 3 of these fail..
good thing is it was stuck at 78 degrees.. 
E Heaters | Submersible Aquarium Heaters | Fluval

Have some old Marinelands that have been bullet proof for many years...

Today is my corporate rant day.. They think of nothing but profits and manuf as cheap as possible.. any brand really..

One heater per tank is never enough...

Sorry disagree as to the difficult to make user friendly..nor is technology sig. more expensive really..

IN case you are wondering, this issue goes way back...

http://www.reefcentral.com/forums/showthread.php?t=2375870


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