Quote Originally Posted by Angelfish11788 View Post
I just feel i am wasteing money but in ideal 2 should be more economical,
No it isn't.

Two heaters are no more economical, If that were the case then 5 heaters would be even MORE economical.

It takes the same amount of energy to raise the temp of a given volume of water no matter how many heaters you put on it.

If you mean the efficiency of the various heaters this is a different thing altogether.
I know one is fine since it kept my 75 a constant 81 but the new one is a bit off apparently
If the new one is off it is because you calibrated it that way, If they were calibrated the same they would behave identically.