5500 watt elec hot water heater - 5000 watt generator

[spam disintegrator]

Hello all,

I'm looking at replacing my current 80 gallon electric water heater. The current heater says the upper and lower elements are both around

3300 watts.

Most 80 gallon units I have seen in stores nowadays are 5500 watt units (upper and lower element are both 5500 watt).

I currently have a 5000 watt gasoline powered generator. Our house is wired with a transfer switch, and the current water heater is already wired into the transfer switch. We have crappy electric service, which is why I bought the generator a couple of years ago. We have had outtages lasting 1-2 days. In my area we had an ice storm a couple years back- remarkably, our crumby power stayed on, while most others were out for between 1-2 weeks. My point? We have outtages that last more than 3 or 4 hours, so there is a good chance we would need to heat water using my generator. I have used the generator to heat our water between showers when we were down for a day or so.

At my list visit to Lowes, I talked to a guy working there and explained my generator situation to him. He recommended that I buy the

80 gal electric unit I was looking at and just buy some lower watt heating elements to replace the higher watt ones that come with the unit from the factory. He said he had done the same thing at his house with no problem. Are there any problems that he or I don't know about by doing this? (other than it will take a little longer to convert incoming cold water to hot).

He claimed that by using the lower watt element it takes less energy to heat the water - he compared it to cars you can buy with two different size engines- one uses more gas than the others. I don't buy that. I didn't argue with him there at the store, but I believe it takes the same amount of energy to heat the water, just a longer time to use the same amount of energy to heat the same quantity of water.

The other thing I thought about doing was keeping the 5500 watt elements in it as is, and buying some extra lower watt elements for emergencies where we would need to heat water using the generator. I have never had to replace an element before- if you need to swap out both the top and bottom elements, do you have to drain the whole water heater, or can you do a fast swap, plugging the hole with a towel, etc. while you quickly switch each of them out? The heater is down in our unfinished basement, so if a little water got on the floor, it wouldn't be the end of the world.

Thanks in advance for your advice!

[bill allemann]

why not disconnect the upper element when you're using the generator.

You could even wire in a switch to shut off externally.

[Doug Miller]

[snip] If natural gas (or LP) is available, I'd be looking at that as the first option...

[barry]

Couple things:

1. Electric water heaters have never been known for their recovery rate, at least not in a good way.
2. They are very expensive to operate, unless you have unusually low electric rates, because of limited efficiency of generating plant.
3. In all that I've seen, the elements are _not_ powered in parallel; either to top one is on until upper section is heated, or the lower one is on as needed. Derating them should not be an issue; just a little bit tedious to do it right removing and replacing.

Suggestions: Solar, gas/propane, derated elements in electric, with use of cogen. The latter meaning: recover some of the 75-80% input loss (exhaust, engine cooling) of your generator into heating water.

J la

[HeyBub]

For what do you need hot water?

Is this need so compelling that you can't heat what you need on a hot plate for a couple of days?

[spam disintegrator]

yeah, i agree with another poster- either the top or the bottom element is on, not both at once. And, each is 5500 watt when either is on.

also, we live in a semi-rural area- there is no natural gas line past our house. LP is not a near term option for us- we would have to bury gas line and the way our property is, i don't see a good spot for a tank where the delivery truck could reach his line to from our driveway. I know and agree with others that LP or nat gas is the most energy effecient. Trust me, if we were set up already for gas, we would have a gas dryer, hot water heater, range etc.

i also have a 2nd part to my question- Sears has a 12 year water heater on their web site. If you want to see what i'm talking about, go to sears.com and paste the item number into the search box. Then click the product specs tab. I'm looking at the Kenmore Power Miser 12- sears item # 04232184000, in the product specs it lists an alternate dual power option.

here is what it says: "Alternate Dual Power- Max Fuse Req'd- 20 amps; Minimum wire size - 12 ga; Wattage at 240V - 3800 watts"

yet, at the bottom of the page, it says: "Power - Type - Electric; Wattage at 240V - 5500 watts; Max Fuse Req'd

30 amps; Min wire size 10 ga"

When I called Sears cust service, I didn't get a warm fuzzy feeling that the woman on the other end knew what she was talking about. She said there is a bar that comes with the heater and that you put the bar somewhere to make the electric work different (3800 watts vs 5500). If this is true, it would possibly be an easy switch to run off of my generator. What I'm wondering is if the lower watt option is possibly for use in mobile homes, where the wiring is less beefy and different quality than in regular homes. Again, I didn't hang up the phone with a lot of confidence that she knew what she was talking about.

Thanks again!

[spam disintegrator]

bathing

[Toller]

Your salesman is crazy. Electric heat is 100% efficient no matter how you do it. The only loss is through the insulation, and the insulation doesn't care what the elements are.

Consider running the heater on 120v during outages. It will only product

1375w, so your recovery time will be terrible, but it will work and doesn't cost anything. It would be better if you could get both elements to run at the same time, but I don't think that are designed that way.

[larryc]

There is no problem swapping out the elements to lower power. Recovery will be slower, but that is the only downside. I have a 3700 watt Sears 35 gallon unit, and my 4400 watt generator runs it fine. I heat a tank of water, turn the tank off and start the well pump. My wife had the flu during our last outage, and being able to take a hot shower did a lot to make her feel more comfortable. With 2 gpm shower heads, a 35 gallon tank translates to a really long shower.

Swapping elements is not something you want to do in the middle of a power outage. Yes, you have to drain the whole tank.

[Joseph Meehan]

Personally I would use a hot plate. Can't you get by a few days without a hot shower? Trying to heat water with a generator is likely going to put a lot of wear on the generator. Those are going to be real expensive baths.

[nicksanspam]

Which probably makes about 20 kW of "waste heat" :-)

Nick

[HeyBub]

Oh. Well, you could go French.

[hallerb]

I suggest you TRY your generator on the tank. Its very possible it might run ok, although it will; be full load...........

Most enerators understate capacity and it may heat a bit slower while still heating acceptably.I aSKED A FRIEND WHOS OLD HOME RAN ON GENERATOR DURIUNG EMERGENCIES he had no choice being on A WELL

His 5KW generator tolerated his 5500 watt tank ok, although heating was a bit slower

[spam disintegrator]

I don't know about that. That might be "pushing the envelop" a little too much.

We got the generator to run a sump pump when the power goes off. That is the primary use if the pump needs to run a lot. If the pump isn't running hard, we can turn it off and run the water heater, well pump, etc.

I'd hate to fry our generator and then have to buy a new one or end up with a few inches of water in our basement.

[trader4]

I take it a gas fired water heater is not an option? I'm not sure I'd run a generator just to heat hot water. With power out and a tank of hot water, it's going to last a day or so if you use it sparingly. But if you want to use lower wattage elements, that is certainly an option. And you;re right, the bozo at HD doesn't know what he's talking about. It's going to take the same amount of energy with the lower wattage elements to heat the water, just over a longer time.

Even at 3500 watts or so, it still going to be sucking up most of the generator capacity for a long period of time. And I sure wouldn't try running a 5KW generator on a 5500KW water heater, as it will already be overloaded and then what about the rest of the house load for the next bunch of hours while it;s heating? Don't know about you, but I'd rather have the furnace, frig and lights going instead of the WH. You can just heat a pan of water occasionally as needed. People lived without showers for 1000's of years.

[spam disintegrator]

yeah, gas fired water heater not an option. i'm not above going without a shower for a day or two- on the weekend. However, I wear a shirt and tie during the week. If it's summer time, I sure don't want to show up for work smelling ripe. And yes, we have a propane camp stove to heat water and cook with in an emergency in the summer time, as well as a wood burner and fireplace if it's winter time.

I would just like to have the hot water tank available if we would be down for a week etc.

anyone heard of the dual power option I mentioned a few posts back from Sears? Is this typical with any water heater you buy or just Sears?

I called and talked to another person at Sears. She tells me that the upper element is 3800 watts and the lower is 5500 watt. There is a "bus bar" that you can convert the lower element to only run at 3800 watts. Of course she promised she would email me a copy of the owner's manual- 12 hours ago (no email, big surprise).

[trader4]

Did you look at Sears support online? Many times the manuals and documentation are there to download.

[nicksanspam]

Then again, you generator makes about 20 kW of "waste heat" :-)

Nick

[hallerb]

Then swich off lower 5500 heater during outages and take quick showers

[Ashton Crusher]

You will not want to mess with swapping out elements when an emergency hits. First off the water will be hot so you'll have to do more then just stuff a towel in the opening if you don't want to get burned. One of the other posters said put a switch on or just run one element. What about a compromise, change out just one of the 5500 elements to a lower wattage element and put a switch in to disconnect the other 5500 element so it won't go on. Be sure and check the logic of the system, mine has two elements but only one can run at a time, first it heats up the water in (I can't recall if its the top or bottom element) then it shuts it off and the other element is then able to turn on. For several months, as it turned out, one of my elements was burned out and so only one was working, we never even knew it till we had company and discovered we were running out of hot water too soon.

Having said all that, elements are cheap, the simplest thing to do would be as the sales guy suggested and just change the two elements to 3000 watt ones. It will take longer to heat water but you'll have a full tank of hot water once it's hot. Make sure it only runs one element at a time, I'm pretty sure all of them are like that now days as both elements would draw way too much current if run at the same time.