whats the most important, the watts or voltage of a device

[Potatohead]

All I can say is you are doing the right thing calculating the draw on your breaker. My question is, is it a dedicated circuit like above mentioned (no lights or microwave). Just saying . it's a 20 amp breaker isn't what you should go on. What wire size is feeding that receptacle. I'm new to the site I just want to help make sure people know the right facts (no fires). your plug is rated for the draw?(current amps) most receptacles are maybe 15amps how old is your home?

Well if he ran a new 20A circuit for the tank it should be 12 gauge. That is standard stuff, based on your other post I’m sure you probably know more than I do. 15A is usually 14. Definitely true you don’t want to run more than 1500 constant watts through 14g so a 20A breaker is useless at that point and actually quite dangerous. If he swapped a 15 to a 20 and didn’t change the wire he most definitely wants to change that back.

It sounds like his setup is only going to pull 900 or so anyway so it’s kind of a moot point.