water heater - what type best match for geo system?

Discussion in 'General Discussions' started by sunnyflies, Aug 30, 2009.

  1. sunnyflies

    sunnyflies Member Forum Leader

    I am looking for the most efficient way to heat our hot water once we put in a geo system and am having trouble understanding what would work best with whatever seasonal heat boost I will get from a desuperheater. I believe I will need a storage tank for the desuperheater's water, then a conventional water heater to raise the temp of the stored hot water to a useable level. So, two insulated tanks in a series with the second one set up to heat the water to a usable level.

    Both my plumber and two propane gas companies have told me I should get an on demand water heater. Yet, I think I have read that they are not the best way to go. One thread referred to a poll on this site a while back of professionals who were against them, however I was not able to find the thread with the poll and discussion, so couldn't read the reasons why. I think it may be because the stored water from the desuperheater might be a high enough temperatue at times that the
    on demand won't work as well/turn on. Is that it? None of the three men who suggested it have experience with geo systems. They just sell water heaters and like the instant, on demand types.

    I am taking out our buried oil tank, so unless I put an oil tank in my basement (which I don't want to do) I can't use our current water heater. Natural gas is not an option, it would cost $18,000 just to bring it to my house. So, it seems the options are electric or propane. But, which is better? Propane would run between $3.49 and $2.79 a gallon depending on my usage. Electric rates in my area run about 19.48 cents per Kwh, among the highest in the nation.

    Recently, I have been reading about heatpump waterheaters, and that they are more efficent than standard water heaters. Is that so? Do they work well? And, are they reliable?

    I would appreciate any advice about water heaters to use with a geo system. Thanks.
  2. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Sunny, thats a tough one.

    Across the sound from you I have two air to water units, both with desuperheating loops feeding an eighty gallon electric hot water tank. The HWG circuits are plumbed in with check valves so each can contribute to the hot water tank. I did wire the elements in this system so the tank could be powered if needed. The water is then finished to a temperature high enough to prevent legionella by a propane fired tankless hot water maker. The tankless responds to water flow and does not seem to mind the reduced delta T when finishing the tank water to a usable temperature.

    Engineer is going on about his water heater/heat pump on another thread. I have not used them yet but they are of interest to me.

    I suppose you could determine how much hot water you use then do the math. Tankless units can qualify for a tax credit.
  3. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    A conventional storage electric water heater, assuming space is available should be a cheap, reliable, economical and efficient solution. The desuperheater should knock 1/2 or more off your hot water energy needs, so the electric elements won't run as much.

    Joe Ami did a straw poll here or at GreenBuildingTalk, and the consensus among pros was that, other than in certain limited circumstances, tankless is more costly and potentially troublesome.
  4. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    I haven't looked, by I think the thread title was "straw poll" which may be why your topigraphical search yielded no results.
    Our unscientific research showed that most contractors preferred simplicity. It is worth noting that the sample was small (maybe 1/2 dozen or so pro's) and at least 2 (who's opinions I respect)had or would have on demand heaters (obviously Mark was one of them).
    I'm an Amana dealer for my fossil fuel line and fortunately didn't install any of their HTMs (95% efficient furnace that made hot water as well) but serviced many of them. With that history I developed a KISS philosophy where hot water is concerned, believing
    that simplicity is it's own economy. I am also an ROIcentric salesman in an area with electricity as low as .07centsKW and natural gas is often available.
    I think my tune might change in areas with higher energy costs.
    Good Luck,
    (when is the big day on ur geo installation.....have we picked a year yet?:)
  5. sunnyflies

    sunnyflies Member Forum Leader

    Actually, within the next four weeks.

    I checked with my town to be sure I don't need a permit for a geo system or its wells - I don't, so can start anytime. I am just waiting for a few esimates on the addition I am going to be putting on my house to decide whether I can afford to go with two stories or only one - a last minute inspiration that would solve a mulitude of problems. I am contracting everything myself to make it do-able, so it takes time as I am not a pro. Lots of learning here.

    I have decided to go with closed loops as my water is quite acidy, plus has lots of iron, manganese and calcium. It's more expensive, but I think is necessary. Ground water is about 30' below in sandy, rock free soil. I've been told I will need three 300' loops, but the driller says 4 @ 220", which is pretty similar. Cost is about $18,000.

    After meeting with about a dozen installers over the last six months, I believe only two of them truly know what they are doing with geo. Many, while probably great with fossil fuels, knew very little about geo, even though they were happily putting them in all over Long Island. A few even were recommended by our power company as geo installers. I can assure you that it's a scary world for consumers out there. I was given proposals that ranged from 3 to 6 tons for the same space, a manual J clearly done for someone elses' house and a lot of song and dance routines that didn't make sense based on what I had learned at forums like this one.

    My 170 yr old house is 2400 sq ft and I will be adding 1025 more. I may be adding another 500 or 600 to that if I put on a second story. So, in all, probably 3425 sq ft, - 4000 max. (That seems so big!) I am being told I need 4 tons for the 3425. I don't know if that would have to be increased if I do add the extra sq footage. My basement is insulated, there's blown in rockwool insulation in the walls and fiberglass bats in the attic where I plan on adding more.

    I am leaning towards a 4 ton WaterFurnace envision, but also looking at a Hydron unit that would provide hydronic heat as well as hot air, or so I have been told. I have a price on the first but not the second. I should have it soon. I have a feeling having both radiant and air will be more expensive than I can afford. My estimates look as if the WF plus the closed loops will run me about $45,000. Gulp.

    Which would be a better way to go, if the costs were the same? Which is more relable, which is quieter? There's so much I'd like to know.

    Plus, I still don't know what sort of waterheater would be best, electric or propane. (Natural gas is not an option) I will look up the straw poll and read through it. I thought I remembered that there was a possible problem with legionella. I asked the gas guys and the plumber about it and all said they didn't know of any, but I wasn't reassured.
  6. geome

    geome Member Forum Leader

    If you plan to be in the house a LONG time and don't want to be bothered replacing a steel tank due to corrosion (as was the case with us), you may want to consider a Marathon water heater (electric). The company is owned by Rheem. The tank is a plastic (no corrosion, no anode) and it has a lifetime warranty from the manufacturer. The manufacturer also claims an excellent 5 degree heat loss for a 24 hour period. The bad news is high price. One 85 gallon tank can go for $1,100 or so. The smaller tanks don't seem to be much cheaper.
  7. sunnyflies

    sunnyflies Member Forum Leader

    Thanks, that's good advice as this is our forever house. Everything I am going to be doing to it is for the long haul, so we can age in place now that our youngest is going off to college. I want things to be good quality, or as good as I can afford. (Tiffany's is not in my budget.) Our water being as acidy as it is, corrosion is a problem. We just replaced the anodes in our current water heater and there was virtually nothing left of them.
  8. sunnyflies

    sunnyflies Member Forum Leader

    Question: Can I use my current hot water heater as the holding tank for the desuper heater's water? And have it plumbed in series with a new water heater, like a Marathon? That way I would not have to buy an extra holding tank just now which would save me a bit. Or, would that be false economy?

    Actually, first, I guess I am going to need to determine what size water heater I am going to need for my expanding house. I may need a larger unit than I have, so I probably can not use it. I've been living with one bathroom and a tiny kitchen for so long that it's hard to think outside of that box. It would be nice not to have to wait for the water to heat up between people using it. Plus, I am finally putting in several new bathrooms. It would have been helpful if the plumber had given me an indication in his esimate for plumbing them, but he didn't. I'll ask tomorrow.

    Should the holding tank be the same size as the tank that actually heats the water? I am guessing that is the case.
  9. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    I second the motion for Marathon - excellent product but pricey, and ROI over standard tanks may exceed your life expectancy.

    I have twin 80 gallon GEs (made by Rheem). Sometimes I wish I'd gone with Marathon for the lower standby loss and expected lifetime, but the differential cost probably would have exceeded $1k.

    I missed your comments about water quality - if your water is hard on steel heaters then Marathon may be more worth the cost.

    There is no ironclad requirement that both tanks be the same size. I would certainly size the main tank for the worst hour of hot water use, and err a bit on the high side. For a forever house keep in mind that todays toddlers will become tomorrow's shower-hogging teens. Having or planning to have a big soaking tub is a factor as well. No point in building a dream house and have it run short of hot water. However, oversizing a water heater increases standby loss, first cost, and space needed.

    My thinking is that the ideal buffer tank size is a day's hot water use. This arises from the fact that hot water generation by recovery from a heat pump occurs gradually over hours and at times of day often quite removed from periods of high hot water use.
  10. sunnyflies

    sunnyflies Member Forum Leader

    My water is indeed hard on steel - and copper pipes. I have a Culligan system, but over the years have learned that it sometimes fails without our noticing it until the iron taste becomes pronounced. When the tank that should even out the PH fails, we don't notice a change, but our pipes do. I have several times discovered pinholes spraying. :(

    If "ROI over standard tanks may exceed your life expectancy", then I think Marathon is the way to go. Mom's almost 90 and her mother lived to 99. Think they might last 40 years?

    While my biggest water users will only be here on weekends from now on, I don't want to undersize. I will talk to a couple of plumbers about sizing as I get estimates for the addition. I think what we have may be too small.
  11. geome

    geome Member Forum Leader

    Don't know if the Marathon will last 40 years, but if not, and if the company is still around, and if they still make them, then you get a new unit. Granted, there are four "if"s in the previous sentence. :lol: I don't remember if you have to pay for the shipping on a replacement unit. Also, it's just the tank that has the lifetime warranty. Thermostat, heaters, etc., are 6 years from what I remember, but check to be sure. I they also make an accessory that might interest you:

    "Titanium Elements: Also available from your Marathon dealer, these can replace both upper and lower elements for applications with harsh water conditions (hard, corrosive, etc). They have proven themselves to hold up even in extremely demanding applications."
  12. sunnyflies

    sunnyflies Member Forum Leader

    Thank you. I will look into them. I think my water might qualify as demanding. I had it tested and am awaiting the final results from the county. I noticed rust in the sink this evening which means the trusty old Culligan system is on the blink again. I guess I had better look into a newer water treatment system.
  13. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    Look into buying a Marathon through an electric cooperative, especially if you are served by one. Mine (Clay Electric) has them available at well below other internet prices.

    If you aren't served by a rural electric cooperative maybe there is one near enough to make the trip worthwhile. You might find a list through Touchstone which I think is an association of cooperatives.
  14. geome

    geome Member Forum Leader

    I agree with engineer on electric cooperatives generally having good pricing on these water heaters. There is a good list of authorized dealers on their web site. We bought ours at a good price and shipped to us from a cooperative about 150 miles away.

    If you are fortunate, and live in an area where your electricity supplier offers them, it is possible that you may be able to get a unit at a $200 to $500 discount. I assume these cooperatives are either selling these units at a deep discount (or possibly even subsidizing them) for their customers to help reduce electricity load due to the lower heat loss of these units. In any event, I found that these cooperatives were only willing to pass on this deep discount to customers of the cooperative. But, as I said earlier, you can still get good pricing if you don't live in an area where your cooperative offers this discount, just not as good. :)
  15. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    A subtlety of the Marathons I noticed lately is that they come with slightly lower wattage heating elements than similarly sized conventional metal tank storage units. This makes them attractive to utilities as it results in lower peak demands on their grids.

    Though lower wattage elements slightly lower the units' first hour ratings and lengthen recovery times, benefits to the owner include less hard water sedimentation and a lower standby generator power requirement.

    The Smart Grid touted and funded by Obama may eventually result in residences facing the same time of day and peak demand charges now only levied on larger commercial and industrial customers. Marathon owners will benefit when that happens.
  16. sunnyflies

    sunnyflies Member Forum Leader

    Unfortunately, there are no co-ops where I live. I will start my search for a marathon heater in the morning. I'm convinced it would be the right one to get. Thanks everyone.

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