How much would it add to my electricity bill to turn on my bathroom's water heater in my condo? In Atlantic City, New Jersey

Question

I've been keeping it off since I moved in, but it would be nice to take some hot or warm showers.

I'm not sure how much electricity it uses, but if someone tells me what to look for, I'll check the labels and update the question.

How much would keeping my 40 gallon water heater on 24/7?

Would it be better to turn it on only before showers?

And how long before showers should I turn it on?

Product info:

• Model No: M240T6DS-1NCWW
• Serial No: FM12729626
• Voltage: 240 / 208 1-Phase AC only 50 / 60 HZ
• Upper-Lower Element/Maximum: 4500 / 3500 Watts based on 60 HZ
• Capacity: 40 gallons / 151.4 liters at 150 psi

Answer 1

For the past few decades, US law has required water heaters and other major appliances to ship with a big yellow "Energyguide" label which shows estimated annual energy cost. If somebody didn't take it off, this is the best place to start.

If it's old or your power is very expensive (e.g. California), the energy prices may be different from what you're paying now, so look for the kWh figure and multiply it by your current rate from your power bill.

If the label is missing, you may try to contact the manufacturer to see if they have this data accessible.

(US Government image)

Answer 2

How water heaters are designed to always be on. Otherwise, they would have better ways to turn them off than cutting off power at the source. If you turn it off for a period of time, the heater must use more electricity to heat the water, possibly more electricity that it would have taken to keep the water at temp, depending on usage. 40 gallons of water will take quite a bit of time to heat up, so you will need to turn it on quite a while before you actually need it, depending on how long it has been off.

Plus the energy spent to heat the water will be disproportionate with the usage - if you need 10 gallons of water for a shower, the heater still has to heat all 40 gallons.

You may also be shortening the life of the heater by turning it off often.

So it's impossible to say deterministically how much electricity you'd save by turning it on or off. My suggestion would be to actually keep it on all the time for a few months and see how much more electricity you use compared to your current method. My guess is you're not saving as much electricity as you think you are.

Another option if you're really concerned about electricity usage is to purchase an on demand heater that only heats water when you ask for it.

Answer 3

$35/month is a ballpark figure based on 4,500W (*assuming that the electricity rate is 13¢ per KWH and the 40-gallon water heater runs for 2 hours per day)