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Thread: Ideas for saving energy

  1. #1

    Default Ideas for saving energy

    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. #2

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    I did some looking around and found another tread that speaks to some of my ideas.
    http://www.terrylove.com/forums/showthread.php?t=26627

    If I did use a re-circulating pump, what make and model might I be looking for?

  3. #3
    DIY Senior Member chris8796's Avatar
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    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. #4

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    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 by franck@geneseo.net; 04-14-2009 at 11:59 AM. Reason: Added more to topic

  5. #5
    DIY Senior Member chris8796's Avatar
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    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. #6
    Master Plumber master plumber mark's Avatar
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    Talking Insualte the hell out of things

    [quote=chris8796

    In my experience conservation and insulation has the biggest payback.[/quote]



    No offence meant...but Marathon water heaters are not all that great


    I would also insualte heavily

    I got a guy who blew 6 inches of foam
    insulation into all his outside walls while building his new home....

    did something similar in the attic too

    I am now wondering how well his winter went.....
    -------------------------------------------------------------

    I would not put the pex in the attic becasue of
    the condensation problems that would happen......forget about it...

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



    Now here is my dream solar system.....tell me what you think of it.....



    If I had a the time and money, I would dig a hole somewhere in the yard and near the house, then install a large septic tank and insualte the sides of it with about 6 inches of styrofoam insuation, also you need to get it near where the panels would need to go..


    this tank would hold about 2000 --3000 gallons of extremely hot water that some solar panels would be constantly heating, ...... this should give you a huge reserve to get through perhaps a few days without the sun...


    this extremely hot water in the tank would be pumped into your forced air hvac system when ever the furnace would come on and pump through a heat exchanger in the phlenum. This basically can and will heat your home... very well indeed...


    also you can put 600 foot of 3/4 pex down in that hot tank and use it to pre-heat the water heater.... no pump required


    these solar panels work with glycol with a
    100 foot copper coil for a heat exchanger sunk deep down in that water tank.... this can and will literally heat that tank as hot as hell during the day
    I have literlaly seen one steaming hot before when I worked on one...



    this system would work with just 2 simple pumps,
    one for the soalr system, and one for when the furance comes on and
    pumps the heat into the house.through the heat exchanger.
    .... and just a small solar controller box..for the heat sensors....



    I think this system is soooo sweet......




    I myself would prefer doing this any day over cutting wood and keeping a wood shack constantly burning all winter long...
    remember if you have neighbors, they can get
    very tired of looking at that shack throwing smoke into the air all winter long.






    just another idea ...

  7. #7

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    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. #8
    Master Plumber master plumber mark's Avatar
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    Talking 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. #9
    DIY Senior Member chris8796's Avatar
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    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. #10
    Plumber jimbo's Avatar
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    Quote Originally Posted by franck@geneseo.net View Post
    .

    .......a few hundred feet of 3/4" PEX water line.....
    That will drop your water pressure by about 2/3. You won't waste much water in the shower, because it will only dribble.



    ...... outdoor wood-fired boiler.
    Now there's a concept which will set the entire clean air effort back to the dark ages.

    You need to rethink some of your ideas, and get some professional design help.

  11. #11
    Master Plumber master plumber mark's Avatar
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    Talking 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. #12

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    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. #13
    In the Trades Gary Swart's Avatar
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    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. #14
    Retired Defense Industry Engineer jadnashua's Avatar
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    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.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  15. #15
    Master Plumber master plumber mark's Avatar
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    Talking unknown variables....for payback

    Quote Originally Posted by franck@geneseo.net View Post
    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.
    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.......








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