Wondering if this is normal for a Eheim Jager heater

[Mihai Boldor]

I am using a Eheim Jager 250w heater and since I got it I could see that it was very often on and the temperature according to my thermometer was just fine so i figured out that it is just very sensitive to temperature changes but now, it was set on 29 C and I could still see the red light turning on very often although my water temperature was 30-31 C, turned it even lower on 28 C and it still turns on for short periods of time(4-5 minutes). I have used other heathers in the past but non would turn on if the water was warmer. So my question would be: is that normal for this kind of heaters?

[DISCUS STU]

It's hard to tell. I use them almost exclusively and have found them to be about the most reliable. If the term. is being kept reliably then all is well. What size tank are you using this for? Is it rated for your tank size?

[Mihai Boldor]

Well I'm still confused it is a 250 w heater for a 240 liter aquarium so it should be ok but why is it still turning on even when my water temperature is ,much higher then the set limit?

[Rudustin]

Well I'm still confused it is a 250 w heater for a 240 liter aquarium so it should be ok but why is it still turning on even when my water temperature is ,much higher then the set limit? I am not a science person but I believe that water is one of the most difficult elements to heat evenly especially if there is water flow. The heater may turn on because at that moment, even though the temperature reading of your thermometer is registering a warm temperature, the heater thermostat is feeling that the flow near it is cooler. There is a constant adjustment that has to be made depending on the size of the tank and the water flow in it. I have a 125 gallon that I just set up and the heater is in the center very low near the bottom of the tank. My thermometer is to the far left of the tank. When I first turned on the heater it indicated that the highest the temperature could go was 89 degrees. However when I set it to the maximum the temperature in twenty four hours was 90 degrees! Way to warm for that tank. I eventually lowered the heater to 81 degrees and my thermometer is registering 84 and half degrees after forty eight hours. So, I think the location of the heater and the water flow and the size of the tank and the location of the thermometer can cause different readings. Hope this helps. Rufus