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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. save$

    save$ Minister of Fire

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    I have an oil fired hot water heater. Not hot water baseboard heat. This has its own burner and only sips oil. My oil tank gage barely moves at all during the non heating season. Last year we used less than 150 gallons for the year and that includes heat oil used to fire the forced hot air furnace to come on when the outside temps drop into the teens. It has been this way for years. Had to replace the water tank after 20 years. Cost me about 1300 for the tank alone.

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  2. maple1

    maple1 Minister of Fire

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    The grounding thing I've never seen or heard of. Huh.

    I do have a ground on my cold water pipe just after the T to the hot water tank feed.

    That exact thing (at top of tank) won't work on mine since there's new pex in the way - but I could do it further away where the pex goes back to copper on its way to the taps.
  3. BradH70

    BradH70 Feeling the Heat

    Joined:
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    South West NH
    Well, I finally took the plunge and installed an electric water heater. I was in need of oil and at $3.80 a gallon it was going to be just about the same cost to install the new water tank -- $475 for the 125 gallon min. I made up a spread sheet with all the supplies needed including plumbing tools and bought every thing in one shot. The price was $536.70. I took this past Friday off from work and did the install myself, both plumbing (first time) and electrical connections. It took me most of the day to do it, but this included cleaning up the space were the tank was to be placed, draining the water lines and the existing tank and then installing the new tank. I had only one issue and that was with the Teflon tape that I used at the NPT couplings on the tank. For whatever reason, the Teflon tape did not seal the threads and I had drips at both the hot and cold connections. I ended up having to go back to the store to get Teflon paste and new NPT couplings to redo that section. Because I had put a ball valve on both cold and hot lines into the new tank, replacing the NPT couplings was not that big of deal and with the Teflon paste, no leaks!

    I also kept the Boiler Mate connected and add a ball valve on the Hot water line coming from it. This allows me to completely isolate the boiler mate from the DW lines and drain the boiler mate, yet still have the ability to use it for DHW if ever needed it in an emergency. I now have the oil furnace shut down! No more oil consumption!

    Next step is to insulate the pipes and get the boiler serviced so that it will be ready to run next time I need to use it.

    One observation so far is that the water coming from the electric tank is much hotter then the water that was coming from the boiler mate. Both are set to 120 so I'm not sure why there was such a difference in water temperature.

    Once I get some electric bills accumulated with the new tank, I will post the additional electric usage that I'm seeing. I hope that it is close to the rated usage of $520/year. This would be a significant savings over the cost of the oil.

    HW_Tank2.JPG
    moey likes this.
  4. moey

    moey Minister of Fire

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    Nice work, you work fast or I work slow took me several weekends. Although I had to put in a subpanel as well, my panel was very full. I also just put in a 80 gallon tank GE/Rheem turned on two days ago. Works great my water is hotter as well I think my boiler water was not 120 despite the settings. I put a mixing valve in as well I have not tried it though yet.

    Electric and oil are pretty close to even in terms of btu cost around me my electric is 13.3kw hr. For hot water though its far far cheaper if your not using your boiler for anything else.

    You should add insulation to your two heat traps it will save you a little bit in the long run. If not it will make it look like you really know what your doing. :)
  5. BradH70

    BradH70 Feeling the Heat

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    Thanks moey. I'm defiantly going to insulate the pipes. I did not do it right away because I wanted to make sure there wasn't going to be any leaks.

    I'm pretty sure I will see some savings. The only reason the boiler was staying hot was for for the DHW since the pellet stoves heat the house entirely.

    I'm also considering switching to a different electric provider (ENH Power). They are charging $0.0728/kwh versus $0.0954/kwh. Sounds like a good savings.
  6. AddictiveStew

    AddictiveStew Member

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    I'm so happy to have read this! I'm planning to do this myself very soon. I'm contemplating just taking the dive now and charging it since I'll be seeing the savings immediately. I have a very old boiler that is only 65% efficient at generating heat for the house. I can only imagine how inefficient it is heating hot water!
  7. moey

    moey Minister of Fire

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    I have a cast iron boiler from the mid 80s. Maintains temp, inactive coil, large mass you get the idea. My estimate was that I was going through about 1-1.5 gallons a day just to make hot water. Go big (80 gallons) if you have a family electric tanks don't recover fast.
    AddictiveStew likes this.
  8. AddictiveStew

    AddictiveStew Member

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    I can only imagine what I'm paying. I just bought this house last year but it came with a VERY old boiler (circa 1930's or 40's I believe?) which is an old coal boiler converted to oil. I don't doubt I'm using at least that much.
  9. BradH70

    BradH70 Feeling the Heat

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    My boiler is a 10 year old Burnham and the efficiency label states 82.5%. I'm guessing it is no longer that efficient. We are a family of 4 (very young kids though) and I was using 20-25 gallons of oil per month for hot water. In my area oil has been fluctuating between $3.60 and $3.80 per gallon. After months of number crunching and being on the fence, the empty oil tank and oil at $3.80/gallon made the decision for me.

    I've talked to lots of people that have installed an electric water tank, some with small families and some with large families. Most everyone guessed at a $40-$50 dollar increase in the electric bill after the tank was installed. Are rates here in NH with PSNH are $0.16/kwh (that includes all fees).
  10. MarkF48

    MarkF48 Burning Hunk

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  11. BradH70

    BradH70 Feeling the Heat

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    Hi Mark, nope, no drain pan. Not sure if I will pay for that later in the future or not, I guess time will tell. I have the tank sitting on a few bricks then a 2" think piece of rigid foam insulation to isolate the bottom of the tank from the cold concrete and bricks.

    My basement is already cold in the winter since the furnace was running only to heat the DHW. So far, it does not seem to be any colder then before the electric tank.
  12. velvetfoot

    velvetfoot Minister of Fire

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    Brad, what do you mean when you say 120 gallon min? Is it a 120 gallon tank?
  13. BradH70

    BradH70 Feeling the Heat

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    Actually it is 125 gallons and this is the minimum gallons per delivery that my oil company will deliver if I'm not on an auto delivery plan.
  14. velvetfoot

    velvetfoot Minister of Fire

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    Thanks, I was thinking the new water heater was 125 gallons; it didn't look it.
  15. AddictiveStew

    AddictiveStew Member

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    I was looking at electric boilers and just ripping out the old oil beast altogether. What has your experience been? I'm hoping with the pellet stove that the boiler will just be backup heat and that's it. I was looking at this one: http://c326988.r88.cf1.rackcdn.com/EB-4.pdf
  16. BradH70

    BradH70 Feeling the Heat

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    Before you make any decisions on a "back up" furnace or heat source, you should consider how long you will be living in the house and that the next person coming in may not want to use a pellet stove. Your best bet is to replace your old furnace with a "back up" furnace that would be considered a standard heating unit for your area.

    In my area the standard heat source/furnace is oil or propane, so I would not consider taking out the oil furnace as this would make selling the house difficult. Not everyone wants to heat with pellets or wood and considering the electric rates in my area, heating the house with only an electric boiler would be very expensive.

    Also consider that if you lost power and your pellet stove went down, it would take a serious generator to run that electric boiler! Even the small one.
  17. AddictiveStew

    AddictiveStew Member

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    I was just looking at the electric usage. WOW. I'll stick with your advice. I just loathe oil... I should post a pic of my old beast, she's HUGE and terribly inefficient.
  18. moey

    moey Minister of Fire

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    Many electric boilers modulate you could in fact run them with a regular generator 5000w size and up, they have circuit breakers you can flip inside the unit. It would be a pain though. Oil/Propane is pretty standard around me too, but electric is getting really close to being equal in cost in my opinion when you consider the real efficiencies of systems. For a small house I would prefer electric now.
  19. velvetfoot

    velvetfoot Minister of Fire

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    I'm not certain about my own electric tariff, but could there be demand charges if consumption goes past a certain point?
  20. ScotL

    ScotL Feeling the Heat

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    The rates in Maine for demand charges are beyond extreme. That's all I have to say about that.
  21. moey

    moey Minister of Fire

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    Business?? How do you end up with demand charges on a residential service?
  22. MasterMech

    MasterMech Guest

    You guys don't want to see the electric bill for my job.

    The building I'm in is currently pulling 1800 amps @ 480V. We do that 24/7. _g

    864Kw for 24 hours = 20,736 KwH every day

    How many KwH do you pay for every month? >>
  23. Mr A

    Mr A Minister of Fire

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    Just about everyone has a electric heat pump in my area. I haven't turned mine on since I put in the wood burner. I kept the thermostat at 65 last winter. I was cold. This winter I kept it off, I was warm. The difference in the bill was $50-$70 a month. The heat pump is only efficient atr +/ -20 degrees the outside temperature. It is OK in my climate most of the year. It the few months of 100+ heat and the month of freeze that really makes it work overtime. I have a 5 yr old electric water heater, well insulated but the bill still goes up $10 a month in a cold month.
  24. woodgeek

    woodgeek Minister of Fire

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    One guy's cheap heat is another guys expensive heat. Where I am, near Philly, it gets cold enough, and a HP is cheap in the sense of costing about half what oil or propane costs, or expensive in the sense of costing a little more than natural gas would. But out east, there are a lot of oil burners without gas access who would be happy to switch to a heat pump, and save a bundle. Without some airsealing and the HP, I would be paying ~$4000/yr for space heat, as many of my neighbors do! _g

    I think the earlier mention of heat pumps was re heat pump water heaters, HPWHs, discussed in many threads around here.
    SmokeyTheBear likes this.
  25. SmokeyTheBear

    SmokeyTheBear Minister of Fire

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    There are something like 29 published tariff schedules for electricity delivery from CMP as long as your use meets the conditions and requirements you can enter into an agreement with CMP using any of the tariffs that apply. Some of those tariffs have demand considerations.

    ScotL definitely knows what the prices are for those tariffs, he is running an operating pellet mill, Maine Woods Pellet to name it.

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