Overheating heater

[prisoner1572]

I am having problems with my two submersible 300w heaters. Both of them never stop heating even on their lowest setting. The shutoff switch seems to be stuck. This is not that big of a problem for one heater since during the winter it won't overheat the tank. The other one would if I kept it in the tank. Is there a way to open and fix these without permanently ruining the water tight seal?

 

[cmor1701d]

How old are these heaters? I was under teh impression that most new heaters failed in the OFF position, not the ON postion. IAre you sure that the heaters are actually producing heat and it's not just an on lamp to let you know it's pluggged in?
If they truly never shut off it's time to get new heaters.

 

[ccCapt]

I have yet to own a heater that stays reliable. I don't think the built in thermostats are what you call high quality. They either don't come on or don't shut off. I highly recommend a Ranco Temp Controller. These are very reliable industrial controllers.

 

[Kurt_Nelson]

Is there a way to open and fix these without permanently ruining the water tight seal?

I wouldn't even go there. The cost of a couple heaters is relatively cheap when you consider what could happen if the repair wasn't done properly.

I'll also second the idea of an independent temperature controller. I installed a Johnson Controls unit on my two heaters and sleep much better at night now.

 

[ezy33]

I found some heater adjustments are back wards, as in counter clockwise for higher temperature. Check the scale if it is then when you think you are turning it down you are really turning it up. As a rule most heaters do fail in the off position, but I've had one cook a Nano tank.