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For non oil burners - how to get hot water

Post in 'The Green Room' started by wannabegreener, Jan 5, 2012.

  1. woodgeek

    woodgeek Minister of Fire

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    Um. If 2/3rds of your usage is standby, how much does preheating the water using a solar system really help? Do you shut down the boiler unless the solar tank is hot?

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  2. Seasoned Oak

    Seasoned Oak Minister of Fire

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    I have a different approach to teenager hour long showers. I have a small electric water heater (30 Gal) set on 120. You can get a nice 15 minute shower but then the water starts getting cold. Nothing limits teen showers like cold water. My dish washer and clothes washer have their own builtin water heaters so they are not affected. The result ,my electric bill barely budges in spring when i convert from HW from my coal boiler to electric for the summer.
  3. woodgeek

    woodgeek Minister of Fire

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    The one I got is like this one--I googled around awhile and found one for $20-30.
    http://enmco.thomasnet.com/item/enm...meters/t18-ac-powered-hour-meter/t18bh52bc09?
    Wired it across the pump/blower motor, it counts when it sees 120V. Multiply by 1.1 gph nozzle to get oil burned, figure out when to buy more.

    If you figure out how many minutes a day you run your shower, and gpm on the shower head, you can ballpark that 80-100 gallons of fuel oil (at 80% eff) should provide the BTUs required for a year of DHW. I confirmed this with my timer, by getting my background reading when I went out of town for a weekend, etc.

    On solar, read the fine print. You still have to pay backup, usually electric. In most cases, the backup will be at least 30%, up to 50% if the system is not properly sized/installed, or your local resource struggles in the winter (as it would in NE). So, solar DHW is not 'free', it costs 30-50% as much as electric DHW. I decided that at that price, the HP water heaters looked a lot more appealing, and had shorter payback (relative to oil or conventional electric).
  4. woodsmaster

    woodsmaster Minister of Fire

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    I have a famly of 5 (3 girls lots of baths ) We used to use elec. WH to the tune of $75.00 / month. I now use
    a wood boiler and the money save on hot water would buy 2/3 of my total wood heating home shop and dhw.
    It was a large investment, so It will be a few years before I see a return.
  5. WES999

    WES999 Minister of Fire

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    I was in the same boat you are in. I was using about 1gl/day in summer for DHW. About $100 mo.
    I found a nice 80gl electric water heater on CL for $50.

    I have an hour meter on the water heater. Over the last year it ran for 180 hr. If I did the numbers right that comes out to $11/mo.

    Now I do have a solar pre-heater so you need to account for that. But when I estimated the cost for electric hot water by itself I came up with $25-$30/mo. (A lot less than $100/mo for oil)

    The $77 dollar figure seems high.

    I think electric can be cheaper than oil.

    BTW the oil man is FIRED. :lol:
  6. otsegony

    otsegony Member

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    This is an interesting discussion for me as I made the move to a GE Geospring heat pump hot water heater. I did this because I was trying to accomplish as much space heating with my basement located wood stove and I found that with a family of four that includes two teenagers providing our DHW through the oil-fired boiler wasn't giving us much savings. Previous to this I had tried various things, including turning the hot water thermostat all the way down or running it at a minimal temperature. All of them saved oil consumption but were vetoed by the family.
    Some facts: total annual oil consumption to heat my 2000' sq.ft. well insulated house in a cold climate and provide hot water was about 700 -750 gallons without the woodstove. I calculated that the DHW took about 250- 300 gallons of that. When I started heating with wood, my oil consumption dropped by at least 50%, but it was hard to get further savings because once the boiler is running for the hot water, why not turn the thermostat up in one of the upstairs rooms and get that comfortable? It was a bit sloppy, but when you are outnumbered by the family it is hard to say no.
    This October I installed the GE Geospring ($1,000 on sale at Lowes) and turned off the power to the boiler. So far electric consumption in Nov and Dec are within 2kw hours of last years (I think the heat pump and the oil boiler with zone pumps have a similar current draw) and our oil consumption in this very mild winter is down to 0. I think that might change if it ever gets below 15 degrees for a sustained period and I have to heat the upstairs bedrooms a bit, but I am still very happy with it. Also, my wood consumption has gone up (not surprisingly) a good amount. I won't know how much until the end of the season when I can calculate total use, but I'm thinking it is going to be in the range of 30 - 40%.
  7. begreen

    begreen Mooderator Staff Member

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    I am looking at the GeoSpring system. For those who what installed one, do you notice the heat loss in the basement? If so, by how much? How difficult was the install? Did you put in a new storage tank or did you use your old electric(?) tank?
  8. woodgeek

    woodgeek Minister of Fire

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    The Geospring is an integrated unit, HP + tank. You might be thinking of the 'AirTap' retrofit system... The all in ones have a significantly better COP than the retrofit approach.
  9. otsegony

    otsegony Member

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    As Woodgeek noted, the Geospring is an integrated unit so it has its own tank. Both Sears and Lowes sells them and you can see them on-one the pages also have comments and downloads like the owners and installation manuals you can look at for your information. As to installing the unit my plumber/electrician hooked it up and said that it was essentially the same as connecting a conventional electric hot water heater, the power needs are the same (a 220v circuit) and the plumbing hook-up was identical. Anyone with any experience with regular hot water heaters would have no difficulty hooking up the Geospring. The unit does seem to cool the basement a little bit, maybe 4 or 5 degrees, but that may also be because I am no longer running the oil-fired boiler with the radiant heat tubes that run through the space. When it is running it puts out a flow of cool air from the heat pump unit. The only thing that I can think of to compare it to would be the air conditioning vents in the center of the dashboard of the car run at a low to moderate setting.
    A couple of other things to keep in mind is the unit is not silent. When the heat pump is running it makes a sound kind of like a dehumidifier running at a high speed, only higher pitched. There are a couple of videos of the unit in operation on Youtube that you might want to check out. Also, if your basement is damp you will need to deal with the condensation that comes off of it. There is a tube that can be directed towards a floor drain or condensate pump. I haven't had any to deal with so far, but my plan in the summer is to just have it run into a bucket and then periodically empty that.
  10. maple1

    maple1 Minister of Fire

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    Have you guys checked out a Geyser?
  11. wannabegreener

    wannabegreener Member

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    Woodmaster, what are you using in the summer. I can't imagine you are using your wood boiler in the summer.
  12. maple1

    maple1 Minister of Fire

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    A wood boiler with well insulated storage is great for DHW in the summer. Fire it once a week and forget about electric or oil heat.

    So nobody's checked out the Geyser?
  13. mrfjsf

    mrfjsf Member

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    As others have said...Go electric. Expensive in comparison to NG or wood but still cheaper than .9 g/day of oil just to heat water. My oil cost is $3.95/gal. My electric bill is $4.25 average cost per day. That is with a 40 gal electric HWH set at approx 140 degs, electric stove, 7 lamp posts going down my driveway, and a wife that doesnt know the meaning of shutting off the lights when you're not in the room.

    You do the math...
  14. wannabegreener

    wannabegreener Member

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    My electric company reports that a 20 gal tank will cost $77 per month to run. Electricity is expensive in NH. I would expect that I would need a larger tank to run than that. Someone saud that a larger tank would cost the same to run, tbut not necessarily. If a 20 gal yap tank is large enoug for a 2 person household (just guessing here) then that means two showers, laundry for two, etc. Tpif the household has 4, then you would almost double youndhw needs. So, I would guess a cost of more than $77.

    I have contacted a company that installs solar to see what they will quote me. I also want to contact a company that installs heat pumps. I currently run a dehumidifier all summer to keep the basement drier, so if the heat pump will do that at the same time as heating water, I might be able to shut the dehumidifier off use the same or maybe a little more electricity for the heat pump.

    I contacted the boiler company 'energy kinetics' and they claim that my boiler should be able to heat dhw with .2 gal of oil per day. This seems a little impossible unless you use almost no water, and the cold water temp is a lot warmer than mine. They claim that their water tank, which I don't have, is a lot more efficient than my superstor. they have some sort of stratifying tank that can suck all of the heat out of the boiler when the dhw stops asking for heat.

    Here are the numbers they also claim.

    They can heat 195 gal in 1 hr with a heat differential of 77 degrees.

    My calculations for this are

    195 gal * 77 deg * 8.34 btu/ deg gal = 125,225 btus
    Their largest nozzle on the boiler they claim this on is 1 gal/hr and they claim an 86.2 % efficiency.

    1 gal * 140,000 *.862 = 120,680 btus.

    With no heat loss in the pipes between the boiler and tank and assuming HW tank could remove all heat from the boiler, they are already almost 4% too low on the btus.

    I'm new at this so if any experts can see an error In my math or equation, I would appreciate it.

    Thanks
  15. wannabegreener

    wannabegreener Member

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    If anyone has first hand knowledge on this unit, I would appreciate your feedback/review of this product.

    Thanks
  16. maple1

    maple1 Minister of Fire

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    There are bits & pieces on it in other older threads here - try some searching. I am also on the lookout for more feedback.
  17. hemlock

    hemlock Feeling the Heat

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    I enquired about one in the spring. There is some guy in New Brunswick that sells them. I can't recall the price, but I remember thinking it seemed a bit expensive compared to prices I had seen in the US (typical for Canada I guess).
  18. hemlock

    hemlock Feeling the Heat

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    I had indirect oil for DHW, and it cost a fortune. Removed the "Triangle Tube" tank and coil, and installed an electric Marathon DHW heater, and have notice substantial savings. I would estimate about $60 per month savings over oil at roughly $4.50 per gallon.
  19. maple1

    maple1 Minister of Fire

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    I did a bunch of net searching this fall - must have found the same fellow that you did. Around Miramichi I think, and around $1200. My current DHW is a coil in an oil boiler that I need to keep hot all year round - so I'm needing to make a change. Still not sure what to though - still leaning to a cold start oil boiler for DHW & heat backup with indirect hot water tank, along with a new wood unit. Decisions decisions...
  20. velvetfoot

    velvetfoot Minister of Fire

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    Can a heat pump be used for heating water for building heat? I haven't seen one. It'd be a way to move heat around when one doesn't have air ducts. If you had a stove in the basement, you could also extract heat with the heat pump and move it to the second floor. :)
    Oil is just too expensive.
  21. Highbeam

    Highbeam Minister of Fire

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    Here's your problem, you're hung up on this.

    A 20 gallon tank costs nothing to run if you don't use it. It can certainly cost more than 77$ if you overuse it. The cost to heat X gallons of water is the same nomatter how big the tank is. A btu is a btu, a watt is a watt.

    When you say heat pump are you considering a heat pump water heater? Those are actually pretty attractive for basement installs where you also need humidity control.
  22. velvetfoot

    velvetfoot Minister of Fire

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    Me? I was talking air to water heat pump for building heat as well as dhw.
  23. woodgeek

    woodgeek Minister of Fire

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    I poo-poo'ed this in another thread....and subsequently heard that Daikin makes the unit you want. Sorry about the OT, but the Daikin
    product has an outdoor coil with defrost controls, etc, and dumps the heat into a hydronic loop. I think the loop should be 'low temp',
    i.e. radiant floor or oversized radiation, etc. I could see it only if you had a not-super cold climate, no need for A/C, low temp hydronic
    radiation AND no ductwork!

    The OP def needs to get a HP water heater....his boiler will tolerate summer long shutdown, which is the only contraindication otherwise.
    An indirect system still has parasitic losses, is expensive, and even if the boiler goes cold between firing the tank, I can't believe all the
    heat gets scavenged out of it at the end of every cycle.
  24. wannabegreener

    wannabegreener Member

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    Highbeam

    I know I'm hung up on this. Mostly because nh has high electric costs. People I known that have electric HW tanks, want to change them because of costs. I understand that if you don't use water, it will be fairly cheap, but I'm assuming I'm using water.

    If I'm using .87 gal of oil a day with an 86% efficient boiler, I'm putting 105,000 btus into heating water. Granted that some of these btus are left over in the boiler and lines leading to the HW tank, I just don't know ho to figure this amount out.

    .87 * 30 days * $3.50 = 91.35 per month for oil

    1 watt-hr is 3.41 btus

    105,000 / 3.41 = 31kwh

    31 khw * $.17/kwh * 30 days = $158.00

    My left over heat would have to be 43% of the total used. I can't imagine it is that high. I have a low mass boiler that tries to dump all extra heat into the last zone asking for heat.

    If my numbers are wrong, please let me know.

    Thanks
  25. wannabegreener

    wannabegreener Member

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    Highbeam

    Yes, I was thinking heat pump for dhw. I currently run a dehumidifier during the summer, so I was thinking/hoping the heat pump would kill 2 birds with 1 stone. Heat my dhw and dehumidify my basement at the same time The heat pump would increase my electric usage/costs, but I wouldn't be running the dehumidifier so maybe somewhere near a wash???

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