DKoKoMan's 150g Reef Tank

[DKoKoMan]

So the other day I noticed my temp was up to 81 degrees Fahrenheit from its normal 79 degrees Fahrenheit. I assumed this was because of the warm weather we have had (30 degrees Celsius). To my surprise when I was looking at my digital temperature gauge, I noticed my one Eheim jäger heater light was on. I physically felt the heater and it was in fact heating... what gives?

I looked in to the matter further and noticed the second heater (exact same heater) did not have the light activated and was not heating. I double check both thermostats and they had not been changed. I proceeded to turn down each a click for good measures, unplugged the one and then plugged it back in. The heater light was on for a bit then cycled off. Within a minute or so the light was back on and the heater was heating already above temperature water. The other heater remained off like it should!

I have unplugged the heater and now have the other one heating the water. Temperature is now back to 79-80 and is being held there. The heater is cycling on and off. I'm guessing my other heater has stuck in or is faulty in some way. I have only had these for 6 months, can't find anything about the product warranty.

I will replace the heater most likely today. Should I get another of the same or does anyone else recommend a more reliable heater they are using?