Am I missing something

[mwoodruff964]

I have the Eheim Jagar heaters one being a 150watt and 125watt for a 90 gallon with a 30 gallon sump where there are located 8inches apart. I have both of them set at 83 F and it will barely get the temp to 78 F. With the house temp between 65-75 depending on time of day. My question is do I need a bigger heater or am I missing something on those heaters, they only stay on for about 15 seconds then they shut off for a while. Think they would stay on longer to reach the set temp.

 

[RocketSurgeon]

Sounds to me like something is not working correctly. You may need more heat, but they should be on , if not at proper temperature.


Perhaps you are trying to pull too much electricity through one particular outlet at one time. Do you have both heaters plugged into the same extension strip? Or are they plugged directly into the wall?

Next, I would fill two 5 gallon buckets with water and heat the buckets of water with each heater in a different rooms, different electrical circuits (breakers).

Record your findings and this should help narrow down your dilemma. Which heater is working properly and which one is not working properly. If both heaters are actually working properly, then their may be an electrical issue.
What else do you have plugged into your circuit with the heaters?

http://www.beananimal.com/articles/aquarium-heaters-what-you-need-to-know!.aspx

It's been a while since I clicked on the above link that I have bookmarked, but i believe their is a chart that helps determine heater watts required.

Edit:

Example:
100 Gallon System
78° Target temp
67° Room temp

Using both the low and high values:
(78 − 67) ÷ 10) × 100 × 3 = 330 Watts
(78 − 67) ÷ 10) × 100 × 5 = 550 Watts

A good place to start would be to use (4) 100W or (3) 150W heaters.

 

[LifeAquatic]

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I think the problem you are dealing with is the heaters are placed to close to each other. Once one heater turns on it heats the water. That hot water passes by the next heater signalling it to shut off. Its always hard to use two heaters next to each other without using some type of aquarium controller. I use a reef keeper to control my Jaggers. I turn the heaters thermostat to about 83. I set my reef keeper to turn on heaters at 76.9 and off at 78. The controller uses its own temp probe to control the heaters so they dont ever shut each other off. Incase the temp probe fails the heaters will never go past 83 becasue ive set the heater theromstat to that setting. Hope that helps. Good luck!