It’s been hot enough here lately that the cold water is warm enough to take a shower (albeit a little cool). I turned the thermostat on the water heater down to 90 to try to save a little electricity, but the water still felt just as hot. I think the control may be broken. But anyway, I decided to turn off the breaker for the heater. It’s a little cooler than preferred for showers and washing dishes, but I can make do. But if it’s only going to cost me a dollar or two per month, I’d rather just turn it back on. How much electricity does the typical home water heater consume per month?
It depends on the size of the tank and the amount of water consumption. For a family of four the number is usually in the neighbourhood of $460 per year. Leaving the water too low can be dangerous because of Legionnaire’s disease and such things. I used to shut my heater off at night through a timer and it didn’t save me fuck all because the tank wasn’t losing enough heat to turn on most nights anyway. Now I only turn it off if leaving for a few days.
Well this is a family of one. It looks like the numbers may make it worth it. According to the chart on Wikipedia, the heated water may be closer to the ideal growth range of Legionellosis (95 to 115 F) than room temperature. Besides, I’d only be using the cold water system. (Why would they grow any faster in a deactivated water heater than in cold water lines anyway?)
How long did you leave the thermostat down for? I recently turned off my water heater while on a week long vacation and the temperature only dropped from 120 to 94 in the tank. Granted I have a blanket on the tank and it is in my hot garage, but if you turned it down and checked a day later, it would likely still be quite hot even if working properly.
Anyway, the numbers in that chart are an average over the whole country over all seasons for four people. Even if you keep it set at 120 F, I bet your monthly cost will be way less to heat that warm “cold” water than the average you would get from that chart. Probably still more than $1-2 a month though.
You may be on to something there. I’ll have to do further experimenting to see if it’s working.
Yeah, the energy needed to heat up water depends more or less linearly on the difference between the starting temperature and the end temperature (yeah, I know that the specific heat of water isn’t constant, but it’s pretty close). So increasing the temperature of the water by, say, 10 degrees will only cost a fifth as much as increasing it by 50 degrees.
There’s probably no such thing as a “typical” home water heater, as their designs vary greatly. Our water heater, for example, heats water only on demand. Thus turning it off when you’re not using hot water doesn’t actually save any money.
Well I turned the thermostat down to 90, killed the breaker labeled for the water heater, and ran bath water (after taking a shower) until it got cool. Now it’s hot again, too hot to touch. Obviously this is a very stubborn water heater that can’t be thwarted by either the thermostat nor the breaker. My multimeter only goes to 200V so I can’t use it to check which breaker is the correct one. My next step is to unplug it. If it still heats up the water, I’m calling an exorcist.
Get a non-contact voltage tester. Here’s the page for one made by Ideal, but there are lots of other brands. Any big box home improvement store will carry them. I got one that has a dial to adjust the sensitivity for around 20$. It will allow you to see if there is voltage present in the wire going to your water heater just by holding the tester close to the wire. Also handy when working on any other electrical jobs around the house.