Mounting Heaters

People will often look at my tanks and ask me why my heaters are positioned "wrong." I put them in the tanks horizontally, not vertically. Well, I just got an object lesson on why this is the way the heater should be mounted.

I have a 29-gallon tank that I usually keep the water level an inch or two low on. It has splashing tetras, and some other jumpy fish. Plus, the tank has a small leak in the upper corner.... if I fill it fully, not only will I lose fish, but I'll get a puddle. Its also one of my few tanks with a heater in it (and the only one without a Cobalt Neo Therm). Well, the water level has been dropping... and I've been busy and lazy.

I went in and found every fish in the tank dead. The temperature is 104. The top quarter of the Eheim heater is out of the water. For some reason, this is where most manufacturers put the thermostat. At this point, it is no longer measuring the temperature of the water, but the temperature of the air around it. The heater has been "on" for who-knows-how-long, attempting to heat the room up... with the tank suffering. If I mounted it horizontally, down at the bottom, as I usually do, this would not have happened.

Plus, it sets up a small convection current, where the warm water from the bottom will "rise" and cooler water will "sink," helping to keep the tank oxygenated at all levels, distribute nutrients, etc.

That sucks!

I've always had them diagonally across the back glass. I've damaged a few heaters by mounting them vertically -

Was it a personal tank or one of the others?


Sent from my iPhone using MonsterAquariaNetwork app

Maybe this is what happened to my quarantine tank... I seem to recall some discussion about the on/off switch malfunctioning if the heater's not mounted vertically...

Matt

Yes, mounting them horizontally has its own risks, as AndyNarwhal once pointed out here:

http://www.capitalcichlids.org/forums/showpost.php?p=151407&postcount=24

Having said that, I mount them horizontally when I can.

The heater cooked your fish not because you placed it incorrectly, but because you selected an over sized heater for the tank.

All heaters will eventually fails, and the first thing to go is the thermostat. When it comes to selecting heater, more is not better. A proper selection is one that is sized to raise the ambient temperature by no more than 5-10F. So even if the heater is stuck, there is no chance to cook the fish.

It is actually better to place the heater horizontally than vertically so the heat rise will be more evenly distributed. But you need to place the heater near the bottom, not the top of water, so dry out cannot happen. Without good circulation, a vertical heater can kick on and off frequently due to concentrated heat rise near the thermostat.

I don't believe that horizontally placed heater is vulnerable to thermo switch failure. Heat is transmitted to the thermo switch by conduction, not convection, so the orientation of the heater doesn't matter.

CichlidAddict said:

The heater cooked your fish not because you placed it incorrectly, but because you selected an over sized heater for the tank.

All heaters will eventually fails, and the first thing to go is the thermostat. When it comes to selecting heater, more is not better. A proper selection is one that is sized to raise the ambient temperature by no more than 5-10F. So even if the heater is stuck, there is no chance to cook the fish.

It is actually better to place the heater horizontally than vertically so the heat rise will be more evenly distributed. But you need to place the heater near the bottom, not the top of water, so dry out cannot happen. Without good circulation, a vertical heater can kick on and off frequently due to concentrated heat rise near the thermostat.

I don't believe that horizontally placed heater is vulnerable to thermo switch failure. Heat is transmitted to the thermostat by conduction, not convection, so the orientation of the heater doesn't matter.

Click to expand...

Hey Andrew while I think everything you wrote is helpful I would have prob re-phrased the fish part.... Also while I'm not an engineer....if a heater coil stays on regardless of amount of degrees it's recommended to increase it can reach temps of 100 + A malfunction is a malfunction. if the heater coil stays on, on a bigger heater, it will heat the water quicker. (Agreed)
Remember regardless of heater the heating element is just a resistance wire/coil that uses 120v and is either on or off.
An example a 150w heater stuck on puts out about 500-510 btus it takes 800+ to raise 100g of water 1 degree Fahrenheit. the tank would go up .5 a degree every hour, compared to a 500w heater which would be four times that an hour at 2 degrees every hour.
Either way they both would/ could reach 104 degrees depending on the amount of time they were on. The smaller heater will give you more time to save the tank.
But too small a heater stresses the heater and can cause failure because the heater itself is over worked.....








Sent from my iPhone using MonsterAquariaNetwork app

I am an engineer and hopefully can explain. When a heater gets stuck, it will continue to generate heat to raise the water temp but at the same time the water will lose heat faster to the surrounding due to greater temp differential. Eventually, the water temp will reach an equilibrium so that heat gain and heat loss balances out. What temp the water will eventually reaches depends on the size of the heater relative to the volume of water and the ambient temp. A proper selection of heater size is one that will not raise equilibrium temp to unacceptable level. Every heater brand has a chart to help you select the right size heater. A larger heater will not only raise the temp faster, but also reach higher equilibrium temp.But don't be greedy to pick one larger than needed even though it costs the same.

I place mine diagonally unless they're in my "display" tanks and I'm trying to hide them. I also tend to use two under-sized ones in longer tanks, rather than one to heat the whole tank.

I will say that I really like the Cobalt neo-therm heaters. Most of mine are Eheim Jaegers, but I'm very slowly switching over here and there. They have a lot of great design features, like not being breakable, having an easy to read temperature setting/thermostat, having superior suction cups for mounting... Really, though, the thing I like the best about them is that they are very short compared to stick heaters. I can put them in a tank, vertically or diagonally, and still have them very well below the water level either way. Yes, they are more expensive, but when you've got a tank with a few hundred dollars worth of fish in it, they're a sound investment.

Andrew,

I would point out that the recommended heater wattage is pretty universally 5 watts per gallon (tank size). This tank actually uses a 100-watt heater, and is a 29-gallon -- which would be a 150-watt heater. The heater is actually smaller than recommended.

Arguably, one could go all sophistic and argue that the volume of the water was reduced by being low, but ... at 2", we are talking 1/9th of the volume or about three gallons, meaning the tank was still a 26-gallon tank, and proper heater would still be 150-watts. If you want to stretch sophistic to absurd, you could make allowances for the gravel and such, but a 100-watt heater is still either appropriate or too small.

Your heater is not over sized according to Eheim chart. I have a 100W Eheim for my 30. I notice Eheim always recommends one size lower than comparable brand.

I can't explain how it can hit 102 unless your ambient temp is 90. Do you have a tall 29?

104 according to my digital.

And, no, just the standard 29 (though it's a metaframe). At least the plants survived, but I'm out my Copella vilmae.

My 30 is located in unheated section of my basement. I set the heater at 78F and the tank temp can only hit the target level in warm months. In winter cold days, the ambient temp is in low 60s and the tank temp cannot climb above 74F despite the heater is on all day long. We have the same 100W Eheim, so I can't explain how yours can hit 104F.

You have a planted tank. Do you provide circulation. You placed your heater on top and if there is heat stratification stagnation of the water column, it can hit high temp on top but not the bottom

Becca said:

I will say that I really like the Cobalt neo-therm heaters. Most of mine are Eheim Jaegers, but I'm very slowly switching over here and there. They have a lot of great design features, like not being breakable, having an easy to read temperature setting/thermostat, having superior suction cups for mounting... Really, though, the thing I like the best about them is that they are very short compared to stick heaters. I can put them in a tank, vertically or diagonally, and still have them very well below the water level either way. Yes, they are more expensive, but when you've got a tank with a few hundred dollars worth of fish in it, they're a sound investment.

Click to expand...

This is good to know. Thanks for the info, Becca! I'm assuming they are reliable heaters.

The larger Neo-Therm heaters (I think 200 watts) were not reliable. I had one blow up on me. Cobalt replaced it with two 100 watt Neo-Therm heaters, which have been great.

Don't buy a 200 watt Neo-Therm without making sure it's a new build.

JLW said:

104 according to my digital.

And, no, just the standard 29 (though it's a metaframe). At least the plants survived, but I'm out my Copella vilmae.

Click to expand...

Oh, not the Vilmae!!!! Say it aint so!

chriscoli said:

Oh, not the Vilmae!!!! Say it aint so!

Click to expand...

See, that was the appropriate response to this post...

And yeah, this is a definite blow to the small, closeted, splash-tetra-loving community .

Yes, when Cobalt first introduced the Neo Therms, they had some serious production issues -- to say the least. It's since been long resolved, and unless you've got an old unit, it shouldn't be an issue.

But, yea, the Vilmae.