I've no answer, except that it could be the inefficiency of operating with only one element (the other with an open), but do to the "only one element is energized at a time" deal, I can't picture how a multi-element heater is any faster or more efficient than one with only one working element...
Anybody have the ability to explain this in a way that my little brain can comprehend?
-Virgil Residential/Commercial Inspector 5 Star Inspections Member IAEI
Re: H2O heater $200/mth#9866 05/17/0210:08 AM05/17/0210:08 AM
I do metering work for a power company, so just a quick calculation, assuming a $100/mo bill increase & $.10/kwhr, that comes out to 1000 kwhrs. or approx 33 kwhrs/day
If the H2O tank is the culprit, then the water either must be very hot (stuck thermostat or grounded element) or the Pressure Temperature Reief valve is releasing the hot water & allowing the water to reheat over & over. To see if it is the second, see if the PTR valve is permanently plumbed to a sink or outside & if so insert a small peice of cloth into the end & check the next day, if the valve operated the cloth will be blown out.
I do hot water tank servicing as part of my job duties & I do not see many high usage problems with H2O tank being the culprit that don't generate complaints that the water is too hot.
If your bill doubled, you should call your local power co & have them reread the meter & if still high test the meter.
Also, the speed of disk in the meter is a very good indication of electrical usage for any given moment. You should periodically check the speed of the disk & if it is spinning fast, start turning off breakers to see which circuit it is on. Once you have the circuit figured out determine if the usage should be expected, in the washer or refrigerator running etc. (This is a good trick for home owners, who do not have clamp-on ammeters avaiable.)
I have seen alot of direct bury feeds to garages & pools be the cause of high bills, due to the insulation on the live leg being cut & the energy being bled off into the ground. I hope this helps.
[This message has been edited by ameterguy (edited 05-17-2002).]
a friend asked the question without giving particulars and i haven't seen him since he asked. he just said he turned off all the breakers when the meter started spinning and turned them on one at a time to find the problem. i didnt have time to ask questions so my 15 second answer was to check the elements and call me in the morning. if its too hot, or leaking, that should be easier to troubleshoot.
but does anyone know what happens in terms of power consumption if an element burns out? will the watt useage increase? seems like it should still operate on 240 if one element goes out. cold water enters the bottom of the tank through the dip tube and the hot water rises, so if the top element goes bad does the top or bottom thermostat keep telling the bottom element to heat up? one element only uses half the power, right? so if it had to work twice as hard to compensate for the other one, twice as much work for half as many elements should roughly balance out, assuming the efficiency of the upper/lower design wasn't a way big deal. if the problem was running out of hot water it might be the lower element isnt helping, but that would mean that it shouldnt use as much power because it is only heating the upper half, so this one doesnt seem likely to increase power consumption either.
so i'm going with the sticking thermostat if its too hot. or the leaking hot water. the grounded element bugs me though. are you saying it could be using/losing power like in a short circuit?
i might be confused by the terms here. grounded element? element burning out?
Cindy, look for simple things first. probably has leak in hot water somewhere,I found a humidifier once with stuck valve running hot water continuously.
Water heater thermostat-- Upper thermostat heats top element till satified then switches to bottom thermostat. If bottom element fails you will only get half capacity of tank, if top element fails you get no hot water (top therm. is never satified so it doesn't switch to bottom). Had one once where element shorted to tank and kept heating(therm. is only single pole) Moral of story, keep lookin'
Re: H2O heater $200/mth#9873 05/18/0206:59 AM05/18/0206:59 AM
I agree that if you lost say the top element, it wouldn't double the bill. It takes so many BTUs to raise the water to the required temperature, so if the electrical input power is reduced it just takes longer to get there while using near-enough the same amount of power. Lose the bottom element and you may just get a smaller amount of hot water as the top thermostat cuts out before the whole contents are hot due to hot water rising.
If you had an element shorted to ground mid-way, then instead of one element connected across 240V you'd effectively have two elements each running on 120V. I'm not sure if your thermostats are single or double-pole, but if SP then the side of the element not on the thermostat would keep running continuously even after the 'stat opens.