Math/Electricity HELP!!!

[chipdouglas]

Hey Guys,

I am horrible at math and need help.

I am considering getting a 12vdc 50watt submersible pump. I need help figuring out how much it will cost to run 12 hours a day.

i will be converting 120vac from my home with a variac and a rectifier.

will this set up have significant electriciy bill savings over just using a 120vac 20watt pump???

It's ok for you to laugh at me lol :na:


Michael.

 

[Benm]

No, a 20 watt 120 vac pump will consume 20 watts. A 50 watt 12 volt model will consume 50 watts, PLUS whatever is lost in the variac and rectifier (for a total of 60 watts or so).

Here in the netherlands we have a rule of thumb that running 1 watt 365x24 costs roughly 2 euros a year. In the US this figure will be lower (perhaps $1.50 or so) since your energy taxes arent as bad as ours.

 

[chipdouglas]

This is where I lose the concept or over think it... So 20 watts @ 12vdc will cost more than 15 watts @120vac? Since I'm reducing the ac so much I thought I'd save a ton

Michael

 

[Sigurthr]

A watt is a watt is a watt, no matter the voltage. You pay for electricity by the watt.

It could be 50Watts at 10,000V and still cost less than 100Watts at 12V.

(Volts x Amps = Watts)

 

[chipdouglas]

Thank you guys. It's amazing how simple something can be when explained properly.

Michael