Heater For 10 Gallon Tank

I have a 10 gallon betta tank that currently has an Aqueon Pro adjustable heater. I purchased this heater in late January when I started the tank. The heater had kept the temperature at a steady 79°F, but all of the sudden I checked my tank thermometer last week and the temperature was 84°F even though I have it set at 79°F. I turned the dial on the heater down to 76°F to try to drop the temperature, and it dropped to 82°F which is still a little too high for my liking. I thought maybe my thermometer was broken, so I got a new one and it shows the same temperature the other one did.
For this reason I want to get a new heater. I've heard great things about Eheim heaters. What brand would you guys suggest for a 10 gallon tank?
Thanks!

 

I've heard good things about Eheim and Hydor. Relatively. People here seem to do well with them. But go to amazon and you'll see plenty of horror stories about people having repeated trouble with both. Could be competitors messing with each other. I'm very curious to see if there really is an affordable, yet reliable heater available on the market. It doesn't seem like that should be such a tall order. IME, thermostat inaccuracy is almost universal with aquarium heaters, par for the course, but can usually be dealt with using simple math.

 

What is the temp your in house? The Cobalt Aquatics Neo-Therm Heater is a good option for a new heater. It comes with a advanced electronic thermostat. You can adjust temp from 66 F to 96 F. It is also designed to be shatterproof and waterproof.

 

I use (50w) ViaAqua Quartz heaters for my tens - because they're cheap. All the ones I've purchased so far have been reliable.

 

Honestly since I covered my 90 gallon it's been 5degrees warmer

... sits right around 79-80 with no heater just an insulated cover. I don't like heaters they're no good. I've almost completely stopped using them

 

I LOVE my Aqueon Pro's, seems like you got a faulty one. Cobalt Neo-Therms are another great heater you could use.