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DHW -- Oil vs Electric, getting closer to real numbers.

Post in 'DIY and General non-hearth advice' started by BradH70, Nov 20, 2012.

  1. maple1

    maple1 Minister of Fire

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    You might have leaks appear, or might not. If so, they're more likely to come from places like fitting joints & circulator pump gasket surfaces. Not sure about 'sections'? Most boilers are all one piece - might depend on what you've got for a boiler & how old it is too. Mine would weep from some fittings & circ pump flanges. Only one way to find out - that's turn it off for a while & let it cool down & see what happens.

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  2. maple1

    maple1 Minister of Fire

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    I don't know why it would be required that a HP water heater be in its own room, or don't think I've read of requirements I'd call crazy. Can you elaborate?
  3. JDenyer236

    JDenyer236 New Member

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    Hybrids do not require there own seperate room. They do require about 700cuft of unobstructed space to allow for free air circulation, garages in the warmer climates are ideal, basements are good in the cooler climates as they are below grade and some heat comes from the earth that is below grade. Most won't run the heat pumps below a certain ambient temp, mine runs down to 45F, after that it uses standard elements just like a regular electric water heater. In Maine I get about 8 months of heating just off the heat pump, runs me about $20 per month. With just the elements it runs $50-60 per month. Hybrids make perfect sense in certain situations. They do produce some noise, and they exhaust cold air into the room that they are in. One needs to take into account for these "features" before buying one.
  4. velvetfoot

    velvetfoot Minister of Fire

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    I guess if you thought of a basement located heat pump water heater as a dehumidifer, maybe you could turn the heat pump part off in the winter so it doesn't get so cold down there. You'd still be ahead of straight resistance on a year-round basis.
  5. maple1

    maple1 Minister of Fire

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    If I was in a situation that I was needing to run a dehumidifier in the summer, I would waste no time in buying a HP water heater and getting rid of the dehumidifier. You would even gain some air conditioning from it - that maybe even could be ducted to where it would be most appreciated.
  6. Harvey Schneider

    Harvey Schneider Minister of Fire

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    Don't forget to add in the non recoverable cost of the water heater. If a tank heater is good for only ten years and costs $600 you have an additional $60/yr expense. I don't think that will tip the scales, but it should be included.
  7. JDenyer236

    JDenyer236 New Member

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    We run a dehumidifier year round in the basement, seems the HP water heater does a great job of removing sensible heat, but not latent heat. I get at most a quart of water per day from the water heater, but at least 50pints per day from my dehumidifier, and this is in the summer when it is humid. I wouldn't install a HP water heater with the hopes of replacing my dehumidifier.
  8. JDenyer236

    JDenyer236 New Member

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    Exactly, you need to include equipment and any maintenance costs to figure out your return on investment. Here is my quick example. I was using 100gals/year of oil just in the 3 summer months for DHW productions. This was at $3.49/gal. So my oil cost was $116/mo. New water heater was $1000, and I use $20/mo for electric. Assuming a 10 year life span my costs including equipment are $29 per month. This is an $87/mo savings, or $1044 per year, essentially making it a 1 year payback on my investment. Even if I ran straight electric and not the heat pump my monthy cost would be $69/mo for a savings of $47/mo or a 2.5 year payback period. My electric rates are $0.14/kwh. As you can see with oil at such a high cost even a cheap straight electric water heater can save you some $$$ with a fairly quick payback. DHW generated by a tankless coil which is most common in the northeast is highly inefficient, that boiler stays hot year round just in case someone needs hot water, most of that heat goes up the chimney in the form of standby losses.
  9. maple1

    maple1 Minister of Fire

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    6.5 gallons of water a day from the dehumidifier? At least? Year round?

    Holy crap. That's a pile of water from the air. The odd time I use one, it's after putting damp wood in and the humidity is very high - I think then the absolute most I ever got was maybe 4 gallons a day. That was at first, then it would decrease as things got drier. Are you sure there aren't bigger issues? Is that typical? I really don't know, our basement is usually quite dry so don't use a dehumidifier much at all - not at all this year.
  10. kofkorn

    kofkorn Feeling the Heat

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    We have it in our basement, so space isn't a concern. With the pellet stove and solar panels on the roof, I hate using two tanks of oil each year just for DHW. I figure that this should save us some big money and with the cost of the heater covered by the rebate, the payback is nearly immediate.

    --Kofkorn
  11. MarkF48

    MarkF48 Burning Hunk

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    I installed a 40 gallon Marathon electric water heater in December 2009 to replace a failed 25 year old oil fired Carlin water heater (this was a separate water heater as I have an oil fired forced hot air furnace). Back in 2008 I had started an "electric bill" spreadsheet to track electric usage. It's just myself and my wife. We live in Central Massachusetts and get our juice from NationalGrid. Back in 2008 the "real" cost of a kwh was about $0.16/kwh. In 2011 it was about $0.138. The replacement cost of the oil fired water heater would have been about $2500-3000 per the estimate from our oil service. The Marathon electric was about $800 and I did the install. The oil water heater also had a yearly cleaning and maintenance which ran about $70. Overall very happy with the Marathon and due to it's construction I don't believe I'll ever need to replace it.
    Depending on where you live some utilities/COOPs were offering rebates on Marathon's.

    http://www.marathonheaters.com/consumers.html

    Electric-Bill.jpg
  12. saladdin

    saladdin Feeling the Heat

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    Thanks.

    How loud is the thing?
  13. saladdin

    saladdin Feeling the Heat

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    This is the one I looked at:

    Where can a GeoSpring hybrid electric heat pump water heater be installed?
    [​IMG]
    The GeoSpring water heater should be installed in a clean, dry area as near as practical to the area of greatest hot water demand to prevent long un-insulated hot water lines from wasting energy and water. It is designed to go into any common indoor installation area including basements, attics, closets, and utility rooms. If the room is smaller than 700 cubic feet, the room should have a louvered door or a door which has vents installed near the top and bottom of the door. Each of these vents should have an area of 240 square inches.


    My water heater is in the kitchen (basements are not common here). With electric WH you can just throw it in the corner no concern for clearance for fans, heat ( it is a heat pump of course). etc...
  14. kofkorn

    kofkorn Feeling the Heat

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    I honestly haven't fired it up yet. I installed the vacuum break on the wrong side of the system, and I need to correct that before filling it up. I'll finish that this weekend.

    --Kofkorn
  15. JDenyer236

    JDenyer236 New Member

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    No this is not year round, mostly spring and summer, I have a typical Maine basement that is always damp, and it does leak when it rains heavily. Fortunatly this is not a finished basement:) Without the dehumidifier the basement would smell moldy and it's not good for the wooden parts of the houses structure.
  16. BradH70

    BradH70 Feeling the Heat

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    I spoke with a local HVAC contractor and he said that he has been installing a lot of electric water heaters lately. I asked him about the electric bill and he believes about a $40/month increase is what people are seeing.

    As for leaving the boiler inactive, it is not a problem because I don't have the on demand tank and coil. He recommended just giving it a throughout cleaning before shutting it down so that when it is turned on again, it will actual work without any issues.

    Install would be about $500 including a 50 gallon metal tank.
  17. saladdin

    saladdin Feeling the Heat

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    Does that include running the electric to it? If so, that's not horrible because a 50 gallon tank is around 300-350ish.
  18. BradH70

    BradH70 Feeling the Heat

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    No, that does not include the electric. I will do that myself.

    Your right, it is not a bad quote. If I did it myself I would have to go out and buy all the necessary plumbing tools and supplies and would probably end up saving $200 at most. I have no experience doing plumbing so if I have a plumber do it I get the piece of mind that it was done right.
  19. lecomte38

    lecomte38 Feeling the Heat

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    The break even point is $.105 per kw at 100% efficiency vs $3.65 per gal at 85% efficiency. I have the highest electric rates by far at .195 per kw. (OUCH) I have both electric and oil. I run the electric in summer and oil in winter. I believe the heat loss of having to heat 14 Gallons of boiler water to pump it thru the Super Store water heater justifies using the electric. ( a good comparison calculator for all fuels can be found at : http://nepacrossroads.com/fuel-comparison-calculator.php
  20. kofkorn

    kofkorn Feeling the Heat

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    The thing about the heat pump water heaters is that they are actually able to get better than 100% efficiency. By drawing heat from the air, they can actually add more heat to the water than if just the electricity was used. I think a typical air source heat pump can achieve about 150% efficiency. Ground source pumps can get around 300%.
  21. TheMightyMoe

    TheMightyMoe Minister of Fire

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    In regards to interior heat pump water heaters.

    They are great, except you use your warm house air to heat your water. A lot of the efficiency you gain, could have been gained with a tempering tank at room temperature.
    This has been one of the bigger arguments VS the government forcing the use of heat pump electric water heaters on us northern climates. We want the heat to stay in our house!



    Also Brad the sweating in of a water heater is one of the easier home projects, that a lot of plumbers you pay will do very quickly, but not do a lot of simple things.

    1. Install the water heater on 2-4 inches of insulated foam. (15$) Cold ground sucks away heat, this also raises your water heater which is preferred.
    2. Use di-electric nipple with plastic lining when connecting pipes to water heater. Also ground your hot water side to the cold side. (5-20$?)
    3. Plumb in heat traps (5-10$?) Supposedly these save 10-20$ a year, so they can almost pay for the water heater.

    I would demand these 3 things. The reason you are switching is to save money, and these will maximize your savings, and ensure a longer water heater life. Electrolytic corrosion is usually what kills water heaters, and the plumbing around it.

    I would also buy a replacement anode rod (40-60 usually$), and tie it to the water heater with a change date @ 4-5 years from install. If you pull old one, and it looks fine, wait a couple years.

    It's funny how simple things, can get complicated when you care.
    briansol likes this.
  22. StihlHead

    StihlHead Guest

    Its the same here in the PNW; the gov't built tons of hydroelectroc dams for refining aluminum. So we have cheap electricity which has been cheaper lately as the rains have been very heavy in the past few years.

    My monthly bill for electric everything exept heat (100% wood stove heat here) is less than the OP for hot water alone. I have a simple electric 40 gallon hot water heater from HD. I think it cost about $300. The spendy electric water heaters there are the same as the cheap ones; its only a waranty that you are paying more money for. Adding 220v wiring and a circuit breaker at the service panel would add more to the install costs, as would a permit (here a permit for adding a DHW is about $150). Romex wiring now is really expensive with the high cost of copper. Oil heat is really steep these days, with the price of gasoline and oil being through the roof. It is by far the most expensive heating in this area. NG and wood are the cheapest. Switching to electric DHW from oil would likely return the cost of converting in the first year though, if you are paying/using that much in fuel oil.

    As for figuring the cost of electricity, you already have electricity and hence an electric bill, so adding the monthy service charge to figure the cost of adding hot water to the electirc rate per KWhr is pretty silly. Just add the costs per KWhr when figuring the cost of electric DHW. Here the cost per KWhr is: 6.8 cents for energy use, 0.2 cents for transmission, and 3.1 cents for distribution for a total of 10.1 cents per KWhr. Then there are about 10 different adjustments that come out to about 1 cent per KWhr credit, and taxes that suck back about 1 cent KWhr (funny how that works) so overall I pay 10 cents a KWhr here. Basic service charge here is $9 a month, but I would pay that anyway, regardless of the DHW fuel. I would stay away from heat pump DHW myself. Gimmiks and rebates and lots of fly-by-night companies there. Heat pumps can be very efficient, but they can also be installed wrong and they cost a lot more, and often times they only pay for themselves through rebates, tax incentives or very long term use.

    I believe in KISS... keep it simple, stupid!
  23. maple1

    maple1 Minister of Fire

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    Grounding the hot water side to the cold water side? Never heard of it - what does that do?
  24. TheMightyMoe

    TheMightyMoe Minister of Fire

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    I only know the basics, but your pipes are generally grounded to get rid of any stray current/safety, but sometimes your hot side is missed / not grounded.

    By making sure the hot side is grounded, you give any electrical current a place to go, which lowers corrosion. Usually you just run a piece of #6 / #8 copper wire between the hot/cold above the water heater.

    Someone else can probably explain it better.

    Water heater.jpg

    Also if I remember right, most of the western world does not use electric grounding like the USA does.
  25. StihlHead

    StihlHead Guest

    Using di-electrics at the DHW will electrically isolate the hot and cold water lines, and thus bonding is required to 're-'connect them. Grounding the hot water pipes stops any potential voltage from forming on the hot water side of the plumbing. The di-electrics stop bi-metal corrosion from happening between the copper pipes and steel water tank.

    Heat traps can be plumbed in for 'free'. Basically all you do is put an up and down 'bell curve' in flexible copper plumbing (hot and cold lines) from the top of the hot water tank. The curve acts as a heat trap and stops convection heat from circulating water (and heat) from your water heater when the hot water is not running. Convection heat rises, but will not fall naturally, which makes these types of simple heat traps work. BTW: Felxible copper water pipes are required for plumbing DHW in many western states for earthquake codes so they can flex during an earthquake without bursting.
    TheMightyMoe likes this.

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