Ever Had A "stuck On" Heater ?

[Rooster]

I read this time and time again, so decided to take a poll on the topic... a LOT of newbies (beginners) come to our forum for advice, and I feel it only fair to separate hearsay from fact.

One of these "ghosts" is that you HAVE to use a specific sized heater for a certain sized tank... and it simply isnt true (in my opinion) !

You are perfectly "safe" in using a larger than recommended heater - the thermostat will sort the temperature.... the only danger that IS possible, but unlikely, is that the thermostat sticks "on" and the water overheats.
But HOW MANY of us have actually HAD THIS HAPPEN ???

For the purposes of sanity, the term HEATER is used to denote a heater+thermostat pair - the most common unit in use.

 

[Schmill]

Please tell me I'm not the only one that was fearful of ticking the "No" box for fear of jinxing my heaters!

My only additional thought with using overpowered heaters would be temperature swing. For exmaple if you have a 50w heater in a 40L tank, once the water gets to temperature the heater switches off (electricity, not heat), and then the residual heat dissapates into the water. Presumably if you had a 300W heater in the same tank then although they will both switch off at the same time, (for arguments sake we'll assume the thermostats are perfect), I'd think that the 300W heater would have alot more residual heat to dissapate into the water once it was off. Whether this would be enough to make any significant temperature change to the water though I have no idea, (and I guess it depends on your definition of 'significant' )

Other than that, as you say, the only problem is with sticking on. In the above example of a 40L tank the 50W heater would take longer to heat the water up to 'fish cooking' temperature, than the 300W one would. It would probably still happen, I guess it just gives you a bit longer to notice the problem, but it would depend on you being vigilant in your temperature checks on the tank either way

 

[simonas]

I had one do this recently in a tank housing a cobra pike cichlid. I didn;t realise till i PUT MY HAND IN AND IT WAS ROASTING

Obviuously changed it and the pike was ok

 

[three-fingers]

I see faulty heaters all the time.

I've had an aqua-one heater stick off (about to send it off for a replacement).

I've also had a rena heater stick off, and then stick on months later when I used it in an emergency (it worked fine for a few weeks before). Right now I'm using the heater again as a stop-gap till the weekend, so fingers crossed.

I've had a visitherm stick off before, but now it seems to be working OK (though not at the temperature its actually set to, and it has condensation in it).

A visiteherm stuck off on my uncles tank. Replaced with a sera, which doesnt heat to the temp its set to and has condensation in it.

Also, at the lfs where I work Saturdays, heaters stick on and off all the time (every tropical tank has its own). I just replaced a visitherm last Saturday after it stuck off and killed most of the fish in the tank (though I cant say I've personally lost stock due to a heater). I replaced another one a couple of weeks before that too, and there are a couple of heaters in there that seem to be stuck off - but there's not much point in replacing them anyway because the temperature never gets very low, and those tanks have things like danios.

 

[Tolak]

I've had cheap heaters stick on, not in quite a while though. These are usually raffle prize heaters, used in a pinch. I have mostly angels, which don't mind the higher temps if one sticks on. I got careless once, used one in a growout tank that had a bristlenose & a few corys. The cats didn't make it at 95F. The coule that stuck on in all angel tanks got pretty warm, but didn't affect the fish.

The only ones I've had stick off, with the indicator light on as well, was when Ebo-Jager sold out, renamed the heaters Jagers, and they had a bad run of heaters. A couple of buddies had the same thing happen, at around the same time. My fishroom sits in the mid 70's, so this was of no major consequence.

 

[rabbut]

I've had Superfish heaters jam off and have seals blow. Heaters jamming on is usualy either due to a cheap heater or an old one thats a bit "tired"... Also, jamming on is almost exclusively a problem that you will come across with By-metalic strip types, as they use a magnet on the "on" contact to ensure a good connection, so as the strip stiffens up with age, it will usualy stick on rather than off due to the magnet...

I half agree with the need to have a specific sized heater in a tank being rubbish, but there is a point to it. Sticking to 1 watt per gallon, you are just about on the edge of what the heater can do in a "Typical" set-up, hence it will spend 1/2 its time on and 1/2 off. Overpowering slightly will reduce the ammount of time the heater is on for, and not the power consumption. Issues arrise when the heater is groseley overpowered. You may note that most manufacturers recomend you leave the heater in the tank for 1/2 an hour before you switch it on for the first time. This is because it take a considerable ammount of time for the thermostats to react to a temperature change. Usualy its about 5 minuites (the time it takes for my heaters to react to a waterchange with just cold water going it and hence caursing a temperature drop in the tank). If the heater is overpowered, heating for 5 mins after the temperature is on target will lead to overheating. The heater will then obviously stay off untill the temperature falls below the disired by a small way. This leads to temperature "bounce" and supposidely stress to the fish... Thats the theory behind the "ghost", and TBH, I've seen it in practice also

I have voted for sticking off but not loosing stock aswell only. Like three-fingers, I see a lot of heater failures at work, and work lost a marine system to a stuck on heater at one point about a year ago. 7 years for a Superfish heater though.... it did well.... Wear and tear issues though, not overpowering ones, actually the heater was "underpowered"... Many heaters used to fail off untill we ripped them all out and went with room heating instead... When a heater failed, it typically tripped the circuit breakers in the fuse box, plunging half the fish room into darkness...

All the best
Rabbut

 

[three-fingers]

I posted this in a another thread, but basically I think that there is a reason behind having the right sized heater, but it's not really all too important, and having one that is slightly over powered isn't much of a problem.

Here's my thoughts:

I think the idea was that it's not recommended over the long run because it may make the heater more likely to stick on (cooking your fish) or less frequently - off (not too much of a problem unless the rooms freezing or it goes unnoticed for ages).

This is just because theoretically, with a smaller heater, when the temp drops .5*C below what it's set to, it will take longer to heat it up - say 5 mins for example.
However with a larger heater, when the temp drops it will take less time to heat it up again - lets say 1 min, after which the temp starts to drop again and they cycle happens faster - meaning the heater is switching between on and off far more often than usual, increasing the likelyhood it will stick in one position (which is pretty common with aquarium heaters).

Obviously the bigger the heater is and the colder the room is the worse the effect.

 

[Piltdownpaul]

Use two heaters to make up the required wattage. If one sticks on the other will switch off (unless you are really unlucky and both stick on) whilst the stuck on one will take longer to heat the tank and give you more time to notice the fault.

 

[rabbut]

This is just because theoretically, with a smaller heater, when the temp drops .5*C below what it's set to, it will take longer to heat it up - say 5 mins for example.
However with a larger heater, when the temp drops it will take less time to heat it up again - lets say 1 min, after which the temp starts to drop again and they cycle happens faster - meaning the heater is switching between on and off far more often than usual, increasing the likelyhood it will stick in one position (which is pretty common with aquarium heaters).

Great theory, but not in practice. Aquarium heater thermostats just aren't that accurate, it takes them a few mins to react to a temperature change, as heat needs to get through the glass to the by-metalic strip and caurse it to flex. It all takes time. The result, both the large and the right sized heaters will take the same time to switch off after reaching the set temperature, but the large heater being of higher wattage than the correct heater, in the same volume of water, will raise the temperature further above the set temperature in the time it takes for it to react, so the temperature "bounces arround" more...

 

[three-fingers]

I see, so that would happen, but because they are inaccurate - the bigger heater heats the water more and the takes even longer to cool down again.

So really, unless your interested in having the temperature set to a very specific temperature for some reason, it doesn't matter how big the heater is - as they switch on and off the same about the amount of times.

Thanks for explaining .

 

[raptorrex]

Use two heaters to make up the required wattage. If one sticks on the other will switch off (unless you are really unlucky and both stick on) whilst the stuck on one will take longer to heat the tank and give you more time to notice the fault.

me too! less complicated than other "safety" systems, but just as effective. i've had "sticks" on and off, but not lost any fish. only because my wife noticed the temp going up though.

 

[rabbut]

I see, so that would happen, but because they are inaccurate - the bigger heater heats the water more and the takes even longer to cool down again.

correct

So really, unless your interested in having the temperature set to a very specific temperature for some reason, it doesn't matter how big the heater is - as they switch on and off the same about the amount of times.

Well no, a larger heater will switch on and off less and the temperature will be in constant swing hour-on-hour Of caurse the rate of swing will be tank size dependant. Larger tanks loose heat slower then small ones, so you may find it acceptable in a larger tank. In tanks that are small however, with too larger heater, the swing can be large... Two heatrers of the correct size though won't caurse this issue, as one will do almost all the work, and the other will idle. Two smaller heaters usualy leads to one doing most of the work, and the other one "topping up" the other

All the best
Rabbut

 

[OohFeeshy]

This is why I've stopped using heaters. Out of all the ones I've had (all sort of brands, from cheap to Visitherm), I've never been truly happy that they're doing their job properly. The room they're in is relatively warm, and personally, I'd rather risk it being a little bit cold than going back to the constant temperature fluctations and risk of cooking when using a heater.