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heater problem


Midas

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Does anyone else have problems with the temperature calibration of tank heaters drifting over time?

After a few years of fish keeping I am gathering an ever increasing pile of heaters that no longer are capable of controlling at 25 deg or below. Some of them are still able to control at a temperature of about 25-26 deg when set at their lowest temperature setting (often 18-20 deg), however the worst one I have controls at about 32 deg when set at 18 deg!

Most of these heaters I have had since new and back then they worked fine. With nearly every heater I buy I seem to have to gradually keep turning them down so that they maintain a temperature of about 25 deg. That is until they can't be turned down any further, which is when I either put up with the higher temp (and hope it doesn't get too much higher) or add them to the pile of clapped out heaters. This problem is not just limited to one brand, I have tried a selection of heaters and they all seem to do this to some degree or another.

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Hi Midas,

the bimetal is probably warped over a period of time.

Open the heater up and reshape the bimetal.

A bit of trial and error maybe but should work fine.

Cheers

Robbo :wink:

Alan said"giving the electrodes a rub down with emery paper"

I wouldn't use emery paper cause you want as flat a contact surface as you can get. We used to use the round part of a crochet hook and smoothen the contact surface.

Hope this helps?

Robbo :wink:

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The way I understand the electrodes wear is for one to become concave, the other convex, by holding the points together with emery paper between them, then pull paper out, it takes off the high spots on each one.

Repeat several times, and the surfaces are dead flat and shaped to its opposite.

Alan

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I think Alan and Robbo are both right :)

a drift in temp settings could be either bimetal warped or contact wear, I would think from what you said that the bimetal is most likely, contact wear is more likely to cause sticking and overheating. but if contacts are pitted and worn then by all means clean them up, use very fine emery or a needle file.

as for pulling them apart, most are just pressed together and pull apart again, slowly and carefully, glass is easily broken, use gloves if holding onto glass tube.

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tip: when sticking them back together again put some kind of sealant like petroleum jelly (Vaseline) around the seals to ensure that they are watertight.

The biggest problem that I have with heaters is condensation and it seems to happen on the new ones as well as the old. The condensate causes the bi-metallic strip to decay resulting in a usless heater.

Because of this I have sworn to replace stock only with the electronic thermostat types like Hagens' Tronic (no bi-metal strip, uses electrics) but even those come apart before they are used and sealed.

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and because i love the sound of my own typing:

The moral of the story is: don't underload/overload your heaters.

For those that can be bothered reading more stuff:

From my experience, here are a few quick ways to harm heaters:

Use a 300w bi-metal heater in a 60l tank

The heater was set to 18degC and kept the tank at a lovely 26degC (because the strips take a little while to adjust during temperature changes & the heater put out a lot of heat in that time). Upon putting it in a 400l tank the heater coil burned out after about a week.

Put a 300w bi-metal heater in a 600l tank

When I was warming up the 600l tank for the first time I went through 3 new 300w heaters. The damn things were on for about 3 days straight in the middle of winter warming up from icy water, running two at a time. The autopsy showed signs of over-heating - melted/burnt insulation, the plastic circuit holder melted in places, blown elements and one bi-metal strip with fused contacts.

Oh, and summer is here! That explains why I gained about 3degC in my tanks!

Incidentally, because New Zealand no longer uses copper coins we officially have a bimetallic currency!

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Dark said:The heater was set to 18degC and kept the tank at a lovely 26degC (because the strips take a little while to adjust during temperature changes & the heater put out a lot of heat in that time

wouldn't the temp fluctuate between below 18degC and 26degC ? When the heater finally stopped putting out heat the temp would have to drop to below 18degC for the thermostat to come back on again? Must have been out of calibration due to bimetal warping ?

:D:D

Robbo :wink:

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As pet my post in saltwater fourm, DARK is on the right track. I went to a fish auction by one of the clubs here. Dozens of 300watt heaters. I run a 300watt on my 700 liter reef, with 250 litres of plumbing, and I will downgrade it to a 250 and see how it goes.

Use the correct heater for the tank, and you will find your heaters lasting longer.

YMMV.

Pies

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I agree, oversizing the heater for the tank is defintely a bad idea in terms of heater life (lots of swicthing on and off).

The first few heaters I brought when I first started fish keeping (from lfs recomendation) were oversized for the tank ie 150W for a 60L tank and 300W for a 200L tank, but not as bad as they could have been. I am now using 300W in a 500L tank and that seems fine (as long as the room temp stays above about 10-15 deg).

I have also brought a Tronic and after about 3 years it is still running at the temperature I set it at back then.

I'll start by haveing a go at dismantling the really bad heater and see if I am sucessful.

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When trying to remove the rubber bung from the glass tube, when it has grown together.

I have used one of those plastic headed pins, slid it down between them both,

then rolled the pin between the fingers, this "walks" it round the bung and breaks it's seal.

Don't rush it, that will only cause breakages, so make sure safety precautions are taken when doing this.

Alan

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i use two 300w 'Tronic' heaters in my 600L

Because the thermostats in them are instant they do not suffer from heating up too high before switching off and they also have that lovely feature that goes something like 'warning, warning, internal temperature of heater too high, disengage power'.

great if you forget to turn them off before removing them from the tank - if...

only problem i have with the electro-therms is that my tronics are set at 29 and 32 degrees and heat up to 26, but almost as if the knob that controls the temp was put at the wrong angle, if i adjust the knob 1degC i get 1degC variation

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You guys must live in igloos or in a cave? 2x 300watt for a 600L tank. 1 Watt a Litre is a LOT of heating.

EBO JAGAR (sp?) can be calabrated for perfect accuracy. The are expensive though, and i have no experance with them. Visitherm heaters are 6/6 in my book so far.

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its more to keep the temperature stable if there is a big change in the atmospheric temp. Living in wellington helps, today it is sunny and warm and the living room will be, but tomorrow it could be freezing cold and wet. because the heaters turn off when the temperature is right they hardly have to run at all.

the elecrto-thermostatic ones sample the water temp every second and average the water temp over a time period to determine whether they should switch on. kinda nifty.

would be interesting to try running a cold water tank if you liived in the tropics - is there such a thing as a water cooler? no wait... i'm not keeping my fish in one of those.

cooling systems?

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Yes you can get aquairum chillers.

Like Ira sais they are very common on reef tanks with mucho lighting.

Strongly disagree with Iras comments that they are expesnive and only used by rich people. I know many people in NZ, and many more overseas with chillers. Infact, if things get any hotter here, I may buy one myself. They people I know that have them are far from rich, including myself. Its just another essential piece of equipment for many people.

They can be purchased for around the $1000.00 NZ.

High tempratures can kill a marine tank. Litterally kill them. If your paying $100 NZ for a piece of coral, or have grown your $25.00 frag into a colonly, having it die too heat is an expesnive problem. Not only does it cost you the coral, you will need to replace it, and your heat problem still exists.

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I consider $1000 to be expensive. Looks like over $1500+ for about a 250watt chiller from a pricelist I've got, but I suppose could be cheaper from other sources. So...Yeah, if you've got a big reef tank that needs it and can't cool it any other way it's cheaper than losing everything in the tank. But still pricy.

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