Should I switch to Electric for Hot Water?

Post in 'DIY and General non-hearth advice' started by daveswoodhauler, Apr 28, 2010.

  1. daveswoodhauler

    daveswoodhauler
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    Ok, here is the deal... I have been monitoring oil useage since December of 2006, and then in 2008 we got our insert. (Did a search on this, but came up empty...I know I saw a similar post a while back)

    I currently have an oil fired boiler, with one of those tankless units above the boiler.

    I have seen a great decrease in oil usage during the winter months due to the insert....gallons per day were appx 3.4 prior to the insert, and we now use about 1.8/day during the same winter months....not 24/7 burners.

    If I look at my oil useage during the non winter months....say early May through the end of Oct, I am using about 1 gallon per day...so at $2.80 a gallon I am spending about $84/month for just hot water when the heat is off....maybe thats not that much/month? Just seems like a lot to me.

    Current electricity costs are 15.1cents/kwh...so I guess I am asking those folks that heat water with electric what their normal useage would be?

    Current household is a party of 5..2 adults, 3 kids....all boys....no one takes a long shower....wash all clothing in cold water.

    Does it make sense to just go to a decent Electric Hot Water Heater? (Assuming oil prices increase at the same rate as electricity)

    Never owned/used electric hot water before, so I have no idea on what a typical monthly useage might be.

    Mods, feel free to post in the green room if it belongs there.
     
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  2. begreen

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    Is solar hot water an option for you? If you have the sun and the roof, it can have a pretty nice payback.
     
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  3. daveswoodhauler

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    I was looking at the solar option as well, so thanks for bringing that up. Roof faces south east, so I think the set up would be pretty good for solar. Have a few large pines in the front yard that would hamper the suns rays from October through March or so, but for the summer it would be great.
    So these type systems work on a electric type backup? (i.e. cloudy for 4 days in a row...what is the backup for the heat)
     
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  4. SolarAndWood

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    I go through this same analysis with our older propane water heater every time I go to get the 3 grill tanks filled. We spend 40 to 50 bucks/mo but also use propane for cooking and grilling. The problem I have with solar dhw is that the same money puts a good dent in a wood boiler/storage and my pile of wood is a lot more reliable than the sun.
     
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  5. ewdudley

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    I used to run the oil boiler all year for hot water when oil was less that $1.50 or so. During the summer the two of us only used a half gallon a day, so what the hell, it kept the boiler warm and dry and maintained. As oil went up that seemed less and less like a great idea so we put in an electric heater. This is for a household of two with no dishwasher, but laundry is washed with warm water.

    On paper a half gallon a day at say 50% efficiency would be 35000 btu / day, or about 10 kW hr, which is enough energy to heat about 50 gallons a day 80F. So switching over I would have expected our electric usage to have gone up about 10 kW hr per day. But in actuality it only went up less than 3.5 kW hr per day.

    My only explanation is that my boiler is a whole lot less than 50% efficient at heating domestic hot water, plus I suspect it took a fair amount of electricity just to run the boiler fan, oil pump, and igniter, not to mention boiler standby and flue heat losses.

    Various rules of thumb for hot water usage for a household of five would run from 40 to 90 gallon per day. At 80 degF deltaT per gallon that would equate to 26500btu/7.8kWhr to 60000btu/17.5kWhr, or $35 to $78 a month assuming high efficiency for the heater.

    So one of the 'nice' things about $3 oil is that $0.15 per kW hr electricity can be economical for hot water heating compared to an oil boiler hot water heater.

    Nicer still would be to take advantage of some solar in the summer at least, but the two of us are using less than $20 per month of hot water so it's hard to work up the ambition to tackle that opportunity.

    --ewd
     
  6. begreen

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    I'd keep it simple with the existing boiler is the backup system.
     
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  7. kenny chaos

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    In my neighborhood, it's mostly electric water heaters and since we went on town water,
    we no longer have issues with burning out elements though that was never a
    real problem, just an occasional problem.
    I don't like my electric bill going up but when weighing all options,
    there is nothing cheaper, steadier and more dependable.
     
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  8. daveswoodhauler

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    Kenny, You bring up a good point, as I have well water and I hadn't thought about that.
    We do have a water softener, but I am guessing that folks with well water tend to have more problems with corroding the elements than with city water?
     
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  9. kenny chaos

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    Corroded hot water heaters, faucets, other plumbing, and coffee makers. But don't let that stop you from considering it.
    Just keep an extra element on hand.
     
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  10. daveswoodhauler

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    Thanks for the tip Kenny.
     
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  11. vvvv

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    Theres a sacrificial rod in the e-water heater tank which should be replaced periodically depending on the mineral content of the water so to save other components. Instant water heaters get plugged up easiest by well water minerals & have no sacrificial rods.
     
  12. firefighterjake

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    I used to heat my domestic hot water with my oil . . . but got rid of it and bought a propane-fueled hot water heater. 1) I hated the idea of having the oil running in middle of the summer and 2) I was always having issues with it (maybe due to the well water.) Since going with the propane I've been pretty happy . . . it seems to run less the oil boiler did . . . but I have considered switching to tankless propane (ie. Rinai).
     
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  13. semipro

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    I think water heating uses a greater percentage of a home's energy than most realize.

    I believe EPA has a spreadsheet available that will let you put in the your local prices for your power source whether propane, electricity, wood, whatever and then compares costs based on heat output whether BTU, therms, whatever.

    Heat pump based water heaters are becoming more common and prices may be coming down. These might be of interest to you.
     
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  14. WES999

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    I posted some info on this subject that may be of interest.
    http://www.hearth.com/econtent/index.php/forums/viewthread/39434/
    You number of $84/ mo just to heat hot water is very close to what I was spending.
    I bought a used electric water from CL for $50 and installed it myself.
    I estimate I am spending about $20 to $25 now for electric.
    I have a heat exchanger on my Fisher stove in the basement to preheat the water in the winter.
    I am in the process of setting up a solar hot water heater for summer, preheating/heating. See (builditsolar.com)
    I am just pitting the finishing touches on a 4' X 8' homemade collector. A home made solar system is not all that difficult to make and
    much cheaper than commercial system.
     
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  15. daveswoodhauler

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    Thanks WES, this is the exact post I was looking for. Thanks much!
     
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  16. gpcollen1

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    This means nothing without knowing what the well water is like. That is false as a blanket statement.
     
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  17. kenny chaos

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    No it's not.
     
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  18. billb3

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    I have well water and it used to supply 5 houses and a bunch of chicken barns until town water came up the street.
    No mineral problems with water heaters.
    Not since 1935 anyway. :)

    I currently have oil-fired hot water. I've had natural gas, propane and electric . Electric can be the slowest to recover from a cold tank.
    I'm pretty close to going solar with electric back up, too, though I'll probably go with a modular rather than a DIY system.
    Be nice to turn the furnace off completely in Summer.
     
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  19. woodsmaster

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    + 1 I have well water and never had a problem with my 13 year old elec. water heater.
     
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  20. jebatty

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    Look at my post in the thread cited above:
    http://www.hearth.com/econtent/index.php/forums/viewthread/39434/

    Note particularly reduction of 50% in electric usage after insulating and heat traps. Also, we have well water and have had no problem at all with corrosion, etc. issues. Well water is not well water in all places. If you have now have no mineral build-up, little or no rust streaks in the sinks and toilets, and your water is naturally quite soft, should be fine. Water softeners do a lot to "clean up" mineral well water; iron removers also available if really needed.
     
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  21. BucksCoBernie

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    I have well water and it definitely corrodes what Kenny listed. I wish I could go tankless but its not an option with my well water.
     
  22. begreen

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    There can be a big difference in mineral content and ph in well water from one region vs another. I remember the well water my sister had in Palm Bay, FL. It stunk of rotten eggs (sulfur) and was acidic. On the other coast of FL, where my FIL lived, the water came up through limestone aquifers. It was sweet and basic.
     
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  23. LLigetfa

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    People that filter and condition their water could see more corrosion. I have in iron filter that aerates the water, adding oxygen to it. I also have a softener that adds salt to the water. Salt and oxygen together corrodes. My water heater only lasted 11 years and I have had to replace many of my fixtures.

    People with whole house RO filters have reported that RO conditioned water will eat copper pipes.
     
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  24. fbelec

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    it all depends where you are. my friend is a plumber. he has a customer in the next town over that goes thru a water heater every 2 to 2.5 years and so did everyone on the same street and area. the ones that had reverse osmosis water filtration systems went from 2 to 2.5 years to 5 years on thier 5 year nat gas fired heaters. the only problem with that filter system is cost. around here some where about 10 to 15 grand.

    dave do you have nat gas?
    we run our boiler for hot water. nat gas 90% eff. aluminum block with a stainless steel superstore tank wired in as a zone of heat.
    it recovers from dead cold in 10 to 15 minutes. so normal run times to heat half a tank is 5 minutes. our gas bill in the summer for gas dryer, grill and hot water are about 35 dollars give or take 5 dollars. and that's with national grid.
     
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  25. fbelec

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    for got to say that our water tank is a 45 gallon tank. to heat a electric 40 gallon tank from dead cold can take 45 minutes give or take 5 minutes.
     
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