I installed an electric water heater for someone today; Kenmore 38gal with upper and lower element.
Installation manual told how to install a sort of jumper to change the lower element from 3800W to 5500W, but there was not a word about WHY one would want to do that. Naturally calling Sears Service just got me into the call center queue for 25 minutes and then disconnected.
I left it in default configuration, but I’m still curious. Can anyone tell me why one would want one of the elements at 5500W? Faster recovery perhaps?
BruceT
Replies
I don't know how you could change the wattage without changing out the element, but the difference would be that the 5500W element draws 22 amps, requiring a 25-30 amp circuit (and larger wire) vs the 16W amps and 20 amp circuit the 3800W element would require.
The larger element would obviously heat the water faster, providing faster "recovery".
There is also sometimes the option of running both elements simultaneously, based only on wiring changes, but that would mean, eg, 3800W or 7600W, if both elements are 3600W.
"I don't know how you could change the wattage without changing out the element, but the difference would be that the 5500W element draws 22 amps, requiring a 25-30 amp circuit (and larger wire) vs the 16W amps and 20 amp circuit the 3800W element would require."Install instructions call for 30A 240V 10ga wire. Existing circuit is pretty good sized stranded wire on 40A 240 breaker.I'm guessing that the "jumper" connects a second smaller coil in the heating element that draws 1700W.
BruceT
Edited 1/6/2009 11:02 pm by brucet9
That does not make any sense.That would require a special heating element.Now heating elements are available in a number of different wattages.Now I think that the standard for 40/50 gal tanks is 5500 watts. But there might be, just guessing, that there might be a market for special units in areas that might have been wired for 20 amps.But then they would just use the 3500 watt element.http://www.drillspot.com/plumbing/water-heaters/water-heater-elements/http://www.plumbingsupply.com/elements.html.Edit - found the manual.http://c.sears.com/assets/own/32636e.pdfAnd that is what they have a special element.Still does not make sense.Quickly looking it looks like all of the tall 40 gal are like that, but the short ones are standard 5500 elements.William the Geezer, the sequel to Billy the Kid - Shoe
Edited 1/7/2009 1:11 am by BillHartmann
"Quickly looking it looks like all of the tall 40 gal are like that, but the short ones are standard 5500 elements."The unit in question was the 40g short. Lower element is listed as "DualWatt"Curiously, the online description of the thing doesn't say why or under what conditions converting to 5500W should be done.DualWatt element is not offered as spare part. Only 3800W or a 5500W elements are available as replacement parts. Maybe the whole thing is done so they won't have to inventory two different products.
BruceT
Yeah, that would be it -- cuts down on inventory. Hopefully you're right and a standard element can be used as a replacement, since they could take you to the cleaners on that special element.The lower power unit is merely to reduce current draw because of the limitations of the existing circuit -- you'd normally use the higher power setting if the circuit is a 30A one.
The mark of the immature man is that he wants to die nobly for a cause, while the mark of a mature man is that he wants to live humbly for one. --Wilhelm Stekel
The circuit is on a 40A 240 breaker, so I should have jumpered it to 5500W?Sears replacement part is either a 3800W or a 5500W; no DualWatt elements sold as replacements.
BruceT
The 5500 watt is OK.But it should only be on 30 amp breaker and #10 (0r larger) wire..
William the Geezer, the sequel to Billy the Kid - Shoe
Yeah, as Bill says, you should replace the 40A breaker with a 30A breaker -- the wiring in the heater is only rated for a 30A breaker. You'll get the best recovery speed by adding in the jumper, but there's no code/safety issue if you don't.
The mark of the immature man is that he wants to die nobly for a cause, while the mark of a mature man is that he wants to live humbly for one. --Wilhelm Stekel
He is talking about the bottom element. Most of the "recovery" actually happens on the top.
Happens both places, depending on usage pattern.
The mark of the immature man is that he wants to die nobly for a cause, while the mark of a mature man is that he wants to live humbly for one. --Wilhelm Stekel
Typically with dual elements, the lower element heats up first (cold water is introduced at the bottom via dip tube). Hot water rises. If hot water consumption is large enough, then the upper thermostat senses cold water. It then switches the upper element on and turns off power to the lower thermostat (which controls the lower element). When the upper element's thermostat is satisfied, power is then switched back to the lower thermostat.Some tanks can be wired for BOTH elements being energized but wiring size and circuit breaker must be sized accodingly.
Quantum materiae materietur marmota monax si marmota monax materiam possit materiari?
You have that backward. The top element comes on first and heats the top of the tank, where the water is drawn (quick recovery), then the bottom is heated to give you capacity.
If your top element is bad you will never have any hot water. A bad bottom element only affects how much hot water you get. A lot of people can go forever with a bad lower element as long as they take short showers.
Yes and no. :-)
On initial startup with a completely cold tank, yes the top element will heat first.
I was refering to an "in use" dual element WH, where all the water is plenty hot and both thermostats are satisfied. As hot water is used, the lower thermostat will energize the lower element first, since the upper thermostat is still satisfied. Upper thermostat will be allowing electrical power to pass down to the lower thermostat.
Also, if the upper element is broken the lower element will still be operable... *IF* .... the upper thermostat doesn't call for heat yet. Once that upper thermostat switches to energize the upper (broken) element, then no power will be sent to the lower thermostat. the water will get cold.
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Quantum materiae materietur marmota monax si marmota monax materiam possit materiari?
I see what you are saying but in my experience the upper will still come on if you use much hot water, like a shower or a load of clothes on "hot". In spite of the dip tube, there is still mixing and the top stat will not be happy. That won't last long but that is what they mean by "quick recovery". If that element is bad the hot water stops being made.
I have seen builder model water heaters that didn't have a top element at all. The water would start cooling off fairly quickly tho. You had to keep adjusting the shower (according to my neighbor who had it). I was surprised when I removed the top cover and saw a plug in the hole and no thermostat. I assumed the top stat was just set very low or defective. It was wired normally and just had a cap splice where the thermostat switch should be going to the bottom element. I ended up cutting off the crimped splice and putting in a top element and thermostat. All was well after that.
Yes, the top element will generally come on during any extended use and will remain on much of the time while water is being drawn. But it will go off pretty soon thereafter, and then the "recovery" period begins where the a full tank of water is reheated.
The mark of the immature man is that he wants to die nobly for a cause, while the mark of a mature man is that he wants to live humbly for one. --Wilhelm Stekel
I guess it is all semantics about what "recovery" and "quick recovery" means. The top element is the quick part. It gives you hot water somewhat immediately.
maybe the sears call center was in India and it was Tea time?
The problem is that the wiring in the heater isn't rated for 40A. You might possibly be legal if you installed a fused disconnect at the heater with 30A fuses in it, but Bill H would know the Ps and Qs of that.
This is a tricky area.The code does not allow it FOR A WATER HEATER.But does for motors.A Fault won't damage #10 wire on a 40 amp breaker. In general the breaker only protects the wiring, not the load.And this is a "known load" so it shouldn't overload.But you might have a thermostat failure that allow both elements on or a element failures to ground that cause higher than normal current draw.And unlike motors they don't have their own overload protection..
William the Geezer, the sequel to Billy the Kid - Shoe