Ideas for saving energy

Discussion in 'Water Heater Forum, Tanks' started by franck@geneseo.net, Apr 13, 2009.

  1. franck@geneseo.net

    franck@geneseo.net New Member

    Messages:
    15
    I recently purchased a Marathon water heater for my new home, which is currently under construction here in northwestern Illinois. When making my decision on purchasing a water heater I considered several factors, none the least of was the fact that my power company offered me a $125.00 rebate on the purchase of an electric water heater. In addition to the rebate I liked the idea of a rust free, wound fiberglass tank. We live in the country and our well water is a bit harsh. Also, by going electric I don't have to worry about the installation and expense of a flue, the safety issues of a malfunctioning gas burner, the energy loss of an always open flue or replacing the combustion air.

    Our new home is 2,200 sq. ft. with a standard kitchen, laundry room, two full baths with an optional third bathroom once the basement is finished (in a few years.) Currently, it's just the wife and I (unless one of the kids moves back in.) I opted for the 85 gallon model. It should meet all our needs.

    Here are some thoughts I'm tossing around to reduce my energy useage.

    I'm considering running a few hundred feet of 3/4" PEX water line through the attic space in an effort to "temper" the cold water supply going into the heater. In the warmer months I'm hoping to raise the ground water temperature 30 degrees or more. I am also considering placing an insulated storage tank in series with the water heater to hold this "tempered" water. I just hate to see all that heat generated in the attic going to waste. To add a bit of complexity to this set up I'm thinking also of adding a thermostatically controlled recirculating pump into the loop. Not being a CPA I haven't crunched any numbers so I don't know if the cost of running the pump outweights any energy savings of pre-heating the water going to the heater.
    To prevent damage in the colder months I would plumb the loop so that I could isolate the attic lines. This would allow me the ability to drain and flush the lines using compressed air.

    During the heating season we intend to supplement our heating requirements with an outdoor wood-fired boiler. As those lines feed into the house they would pass through a heat exchanger in the furnace plenum, then through a coil wrapped around the afore-mentioned tempered water storage tank and finally through a series of heating coils under the kitchen and bathroom floors, then back to the outdoor boilder, all as one, continuous loop. I would include the ability to isolate the floor heating coils in the event that it's too much warmth. We don't want to cook Mama's feet with too much heat radiating up through the flooring!

    One last item I would like to install, and this is more creature comfort than energy savings, but it would be a gravity flow, hot water re-circulating system plumbed to the bathrooms. At this point, what's one more line and a bit of insulation?

    I can see a potential for cost savings with a very minor expenditure. I guess this all falls into the catagory "experimantal plumbing = research and development."

    So, for all you good and gracious professional plumbers, what do you think of my ideas? I know it's a lot of tinkering, but I am retired and enjoy that sort of thing. I look forward to you input. After all, you're the pros! :)
  2. franck@geneseo.net

    franck@geneseo.net New Member

    Messages:
    15
  3. chris8796

    chris8796 New Member

    Messages:
    100
    Location:
    Illinois
    I wouldn't run PEX through the attic, too many potential risks for such a small reward. You could do a DIY solar setup for a little more money and have very little risk.

    I don't have a lot of experience with boiler systems, but I'd want the sub-systems to be controlled individually. They all have different preferred temperature ranges and heat loads. Most of the wood boilers I've seen are coupled with a large heat storage tank (~1000 gals). This gives you alot more flexibility and makes it easier to use wood in the spring and fall, even in the summer for DHW. It also helps in preventing smoke, since you can burn at a constant high rate. Rather than constantly going into idle mode, which tends to produce alot of smoke. In general, wood boilers are only for those deeply commited to burning wood. The biggest complaints I've seen is, the smoke, the volume of wood and the labor to move it, daily monitoring, must constantly feed it and protect it from freezing (you can't take a day off). I think this makes these a poor choice for most people. This a way of life rather than a method of heating.
  4. franck@geneseo.net

    franck@geneseo.net New Member

    Messages:
    15
    I do understand the drawbacks of operating an outdoor wood boiler. We have used a home built airtight wood stove exclusively for the past 30 years to heat our home. There is a like new, 30 year old Heil gas fired furnace sitting in the basemant of the old house. We turned the pilot light off 29 years ago and haven't re-lit it since. And yes, I keeps you married to the woodstove 24/7. I'm assuming the outdoor wood boiler will require more wood to heat our new home than our trusty airtight, but it will allow us the flexibility to go on vacation from time to time, provided we don't have an electrical outage. The circulating pump on the wood boiler runs 24/7. Should the fire go out, the gas fired furnace kicks in and keeps the boiler loop warmed through the heat exchanger. In theory it shouldn't freeze.

    Chris, what drawbacks to the attic loop are you concerned with? Leaks? Installation? Cost? Weight? Using PEX? Please elaborate. I'm here for the education.

    I haven't yet ruled out the solar collector idea, I just need to research it more. Any links would be appreciated.
    Last edited: Apr 14, 2009
  5. chris8796

    chris8796 New Member

    Messages:
    100
    Location:
    Illinois
    I think energy costs will need to go up quite a bit to consider wood. I'm just north of Peoria and have a 2600 sqft house. I checked our gas bills for 10/29-4/1, I used 600 therms at a cost of $658, which provided heat, HW and cooking. We average about 30 therms a month in the summer for HW and cooking (family of 4). That would mean we used about 450 therms (~$500) for heating this winter. There is no way it would be worth the capital costs, labor and wood costs for me to consider it. The coldest month we averaged less than 20K btu/hr with the thermostat set to 70 during awake hours.

    On the PEX, the leak potential is the biggest problem. But you also have to consider the potential for condensation, physical stability (150 degree seasonal temperature swings). If you average 50 gals a day at 30 F temp rise, thats 13200 btu or about 4 kwh. You'll save 40 cents a day and $12 month minus capital costs (PEX, pump, storage tank, heat exchanger, lost interest income) and electricity to have a time bomb over your head. Then you only get these savings in summer. Solar has the potential for more savings, but its still really tight if you look at the numbers.

    In my experience conservation and insulation has the biggest payback.
  6. Insualte the hell out of things

    Last edited: Apr 14, 2009
  7. franck@geneseo.net

    franck@geneseo.net New Member

    Messages:
    15
    Hummm, how about pumping all that heat into an indoor pool, then drawing off that? Seriously though, it's an interesting concept. Are you thinking of a focused parabolic mirror to heat the water? How big of a collector are we talking about?
  8. just plain old solar panels

    all you need is an array of solar panels
    sitting out in the yard faceing south right above that
    tank... the actual amount of panels would have to be calculated to the amount of water you want to boil

    my best guess would be 4

    The roof is good too, but if you have the room and they dont stand out too badly in the yard, I would perfer to have them on the ground..

    also for that matter you could use that wood shed boiler to heat the water tank in the yard.....


    this is actually a very simple system to maintain...

    much easier than chopping wood for the rest of yourlife....

    .unless you like the exercise







  9. chris8796

    chris8796 New Member

    Messages:
    100
    Location:
    Illinois
    A massive storage tank is important if you hope to provide the majority of your heat with solar or similar. I also like the idea of keeping the panels off the house and in a place with easy access. In the midwest, we get about 3 kwh per m^2 per day in the middle of winter and 5-6 in the summer. Its important to minimize your heat use/loss as much as possible. I would also consider a radiant system, just because it can utilize lower temperature water than FA. This increases the usable storage capacity of your tank.
  10. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego

    You need to rethink some of your ideas, and get some professional design help.
  11. 300 feet of pex in the solar tank

    Perhaps you are right about losing some pressure on
    the hot side of the system,

    it depends on how much pressure you have to start with, and how much you are willing to give up to
    passively heat your hot water tank...

    I would have to try it to see , I doubt it would be all that noticeable....


    hell, if the fellow wanted to run that much in the attic, I dont see how it could be any worse


    we got to go green, green, green
  12. franck@geneseo.net

    franck@geneseo.net New Member

    Messages:
    15
    OK, You've talked me away from the attic heat recovery theory. I can see the problems of potential leaks, condensation and the meager returns for the effort invested. I will investigate further the benefits of passive and active solar heating.
    This leads me to another question, radiant heat. I have yet to pour the basement floor. Would it be prudent to embed a radiant heat system for future use? Initially, we will incorporate a forced air furnace (I already have it) to heat the house. As mentioned earlier there is approximately 2400 sq. feet of floor space on the main level with a near equal amount of space in the basement. How long should I expect the investment in a solar collection, storage, and radiant system to pay for itself (roughly).
    If I can find a workable solar solution I would gladly give up the idea of an outdoor wood boiler and it's associated drawbacks.
  13. Gary Swart

    Gary Swart In the Trades

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    7,349
    Location:
    Yakima WA
    Sorry in advance for a negative attitude. I know that "Going Green" is the hip thing to do nowadays, but I can help noting that the old adage of "Penny wise and Pound Foolish" applies to many of the attempts to conserve resources and money. The best return on your dollar is additional insulation and otherwise slowing heat loss.
  14. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,006
    Location:
    New England
    I'd seriously consider embedding a suitable pex tubing (requires an O2 barrier) in your slab. Depending on the size, you may need multiple zones (loops) to keep the heat even. As is true with any slab, prep is crucial, especially if you ever want to heat it. You need to keep both moisture out and provide insulation to the slab, as wet insulation will draw off the heat.
  15. unknown variables....for payback

    to figure out how long it will take to break even on
    the solar systems out there it all depends on who you ask...

    ask a solar salesman and he will have some figures for you.... take whatever he says the payback will be and add probably %30

    understand that at best, you are only going to
    cut your heating bill down by probably half,, maybe more,
    but you will never be totally free of your dependencey on the grid ,

    unless you want to cut that wood all winter long....

    ------------------------------------------------------------


    another very feasable option that would work great in a home with a basement would be a large wood burning stove in the basement.....centrally located......

    you would be suprised how well that works...

    I have just 2 plain old fireplaces and I can keep my home pretty warm on the nasty days.......







  16. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
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    Location:
    Cave Creek, Arizona
    energy

    That electric heater could "use up" the $120.00 rebate in increased energy costs in a matter of a few months. A coil wrapped around a tank will have such a small contact area that it would not even be worth the cost of the material to do it. A recirculation pump is NEVER energy efficient, it is a comfort item and will also add to the energy costs. A thermostat controlled one, if done in the conventional way will measure the temperature of the returned water at the water heater, not at the faucet where the water is used, so the water will not necessarily always be "instant hot water".
  17. Scuba_Dave

    Scuba_Dave Extreme DIY Homeowner

    Messages:
    885
    Location:
    South of Boston, MA
    I just finished a greenhouse, 7x10 x ~6' high - less then $30 cost
    With a sunny 70 degree day it was up to 107 at one point
    I'm going to build a solar air heating system to go in the greenhouse & hook it up to recycle & heat house air
  18. SewerRatz

    SewerRatz Illinois Licensed Plumber

    Messages:
    1,705
    Location:
    Chicago, IL
    Check your local codes

    I now I am a bit late in responding to your post. But I would check with your city or county codes about Pex. Illinois does allow for it but most of the northern counties do not allow pex or CPVC to be used.

    About the radiant heat, if you are considering it, also look into a snow melt system for your walkways and driveway. I have helped install a radiant heat and snow melt system for the Ray Graham Center for the blind in Burr Ridge a few years back. I am really surprised with Northern Illinois cold wet winters that radiant heat and snow melt systems are not more wide spread.
  19. franck@geneseo.net

    franck@geneseo.net New Member

    Messages:
    15
    Yes, I assumed that from the start, but the price of propane has gone up so rapidly here and I don't see that situation improving any time soon. That's why I'm here, throwing all these ideas around and weighing my options. After 30 years of lugging wood around I'm ready to search out alternatives. Copious amounts of insulation, controlling air infiltration, natural lighting and solar collecting appear to be my better options with the least impact on the environment.

    I think I will use a secondary tank to temper the incoming cold water going into the water heater. Even raising the temperature to the room's ambiant temprature should provide a measurable amount of electrical energy savings. Perhaps an older, discarded water heater tank, stripped of it's outer shell and it's insulation would be an inexpensive solution to finding a cheap secondary tank. (Pressure tested first, of course!)

    As for using radiant heat under the sidewalks and the driveway to melt snow, I'm all ears. My garage enterance faces North and I know from experience that that location is the worst for snow and ice removal as it get no natural warming from the sun. My initial questions would be how to set the system up and what type of PEX to use. Someone mentioned an O2 barrier? Where do I purchase the correct PEX and the appropriate components?

    Frankly, the current administration's ideas of "Cap and Trade" scare the daylights out of me. I only see increased costs which ultimately land on the consumer's shoulders. I think we all need to put our thinking caps on and find ways, free from government interferences, to save energy and find workable alternative sources. We, the people, are good at that sort of thing.
  20. SewerRatz

    SewerRatz Illinois Licensed Plumber

    Messages:
    1,705
    Location:
    Chicago, IL
    What city are you in, I can point you to a boiler supply company that can help you design a radiant heat / snow melt system and be able to help you with the proper materials.
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