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gray water heat exchanger

I sent you a diagram Andrew, I can't seem to post pic here, I just get a white screen? You can post it here if you can. One drain comes off the bottom to drain and flush the tank, but that drain is normally shutoff, and on the tank side of the shutoff I have a TY that goes up about 30" then dumps into the sewer, like a trap. This works good because it also drains the coolest water, while trapping the warmer shower water in the top of the tank. They are supposed to show the install on American Builder on the Comcast Network on March 27th. If you have comcast. Thanks, Bob Gagnon

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  • bob eck
    bob eck Member Posts: 930
    gray water heat exchanger

    has anyone used and installed gray water heat exchangersin residential applications to raise the incoming water temp before it goes into the water heater? if so how successful were they in raising the water temp? thanks bob
  • bob eck
    bob eck Member Posts: 930
    gray water heat exchanger

    has anyone used and installed gray water heat exchangers in residential applications to raise the incoming water temp before it goes into the water heater? if so how successful were they in raising the water temp? thanks bob
  • kpc_14
    kpc_14 Member Posts: 38
    I have one...

    in my home. It dooes raise the water temp to the water heater....I do wish I could get more than one shower going into it though.
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  • My grey water system

    I installed a grey water recycling system where I pipe my shower drains to a 150 gallon tank in the basement, I filter, add enzymes and chlorine tablets to the water and use it to flush my toilets, it works great. I wrapped the outside of the tank with 200' of 1" pex, and I inserted a large custom made tankless coil with 1" tappings into the greywater tank. My incoming cold water, which gets as cold as 36 degrees, goes through the pex first then into the tankless coil before going into the hot water tank. I get about a 30 temp rise when the shower is running, and the 105 degree shower water is pouring over the coils, and I get about a 25 degree temp rise when the shower is not running. I get a lot of heat transfer when the water is sitting there, the cold water gets about as hot as the tank. I also get my water bill cut in half because I use the grey water to flush my toilets. I am very happy with the way it has worked out. Water savings alone should pay for the materials in about 6 years.
    Thanks, Bob Gagnon

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  • Larry Weingarten
    Larry Weingarten Member Posts: 3,233
    Yup

    I put in a GFX shower heat exchanger. It collects about 60% of the waste heat. It's piped to put that heat directly into the cold side of the shower, rather than the water heater. I doubt it collects nearly as many BTUs as Bob's system, but it is quite simple, buried in a wall.

    I like and use solar, but measuring BTU's per dollar, efficiency usually beats new energy by three to five fold.

    Yours, Larry
  • ALH_4
    ALH_4 Member Posts: 1,790
    Conservation

    And a low-flow showerhead is the best investment of all. I have always found it interesting how conservation makes alternative energy investment appear worse, yet the two go hand-in-hand.

    Conservation is absolutely the best investment we can make in energy independence.
  • But.....

    You can take longer showers if your going to use the water again to flush the toilets, and if you heat the water you are using for the shower with alternative sources. Thanks, Bob Gagnon

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  • Larry Weingarten
    Larry Weingarten Member Posts: 3,233
    It's interesting...

    ... that calling the beast conservation implies "freezing in the dark" as Reagan put it and calling it efficiency stirs up only positive images. These days, I'm trying to learn to be efficient. Forget about conservation ;~) I'll admit though that I'm having a tough time accepting how green nearly everything claims to be :~P

    That ole "what's in it for me?" that Dan's been telling us about all these years can be used to make efficiency a desirable thing. When efficiency translates to increased comfort, it won't need to be sold, folks will line up!

    Yours, Larry
  • Your right Larry

    If we make green more comfortable people are going to come on board a lot quicker. Let's take it one step further, how about a recycling shower. Fill a tank under the shower, maybe 5 or 10 gallons, with clean water from the shower valve. you recirculate that water in the shower over and over, with maybe a small electric heater, but you would only need to bump it up a few degrees. The tank could have a good sediment filter and a UV filter to kill all bacteria. You could take a shower as long as you wanted to, and you could have as many body sprays as you wanted. Then you dump that water after you are done showering and backwash the filter. The next person starts off with new clean water, and you only use a few gallons of water and a small amount of energy to keep that water up to temp. Now people are going to say they won't shower with water over and over, it might be dirty, but a good filter and UV would make it clean water. It would be a lot cleaner than siting in a hot tub, you are recycling that water over and over, with no filter at all. Any thoughts? Bob Gagnon

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  • ALH_4
    ALH_4 Member Posts: 1,790
    Water Re-use

    I like the ideas of low water use, and water re-use. Your re-use of gray water for toilet flushing is a great idea. Although, I have a feeling the idea of showering in your own gray water will be a tough sell. Do you have a separate pump and pressure tank for the gray water system? I assume you have more gray water than you would flush in the toilets. How did you handle the bypass? What happens if the gray water tank goes dry? Just curious as to the specifics of your system. Is there much maintenance?

    As Larry said, there is no glamour to conservation. "Green" means so many different things to different people that it really means nothing. Check out the "green" mansions in Green Builder magazine. Apparently they are green because they have reduced VOC's? Is a 5,000sf low VOC home for two people green? It might be healthier, but I don't think it's green.
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  • ALH_4
    ALH_4 Member Posts: 1,790
    Gray Water Heat Recovery System

    Thanks for the diagram, Bob. Have you had any issues with scum buildup or anything growing in the tank? Did you size the tank based on anticipated flush volume or for heat recovery?
  • I sized the tank

    for one that I could get in my basement. Brac Grey water systems made and 80 gallon, without heat recovery, and I wanted to do heat recovery so I went with a 150 gallon tank. Brac makes a larger tank now. I figured the larger tank would lessen the likelihood that I would run out of grey water and have to swap back over to potable. I didn't want to tie the grey water directly into the potable. I had a problem with smell in the beginning, in the toilets. I was putting chlorine tablets in the grey water tank and the toilet tank. The good people at Brac told me I had to deliver the chlorine more evenly, they put theirs in the grey water supply near the pump, so I took out the sediment filter and put a couple chlorine tablets in there to deliver it evenly onto the grey water supply pipe, it worked great, no smell. I tried it without chlorine for about a month and it got real stinky and slime built up on the inside on the piping and toilets, but I put enzymes down the shower drain and it ate up all the slime in no time. I add a little enzymes every few days or so. It works out good because you can smell the water a little when the chlorine runs down, but that's the warning to add chlorine, long before slime builds up. I recently ordered a chlorine despenser that slowly despenses the chlorine by using the small flexible hose leading to your overflow pipe that fills the bowl. When you drop a chlorine tab in the toilet tank, you get high contentrations of chlorine when no one flushes for a while, like overnight, and that can harm the workings. Most people think of water as a renewable resource, and it is, but much of the cost of water is electricity, and a lot of our electricity comes from burning coal in the Midwest. So when you save water you are saving electricity, even for those of us that don't have water shortages this makes sense. This is easy, there is no reason to be afraid of grey water use, it's still not approved most places and that is something we have to work on. Thanks, Bob Gagnon

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  • Scott Secor
    Scott Secor Member Posts: 15
    Pump Control

    Bob, how is the pump for the grey water controlled?
  • ALH_4
    ALH_4 Member Posts: 1,790
    Pump control

    Seems to me like you would need a small pressure tank and switch?
  • scott markle_2
    scott markle_2 Member Posts: 611
    grey water

    I use a GFX recovery unit. The copper is apparently effective in resisting scum colonization. This is a very low maintenance device. Even if recovery is less than the manufactures claims I feel this was an good investment.

    Bob, the only thing I don't like about your system is the reliance on chlorine. Perhaps I make more of it's environmental impact than deserved, but it would seem to me that in a region with plentiful water supply the impact of the chlorine may undo much of the "conservation benefit"

    The water flush toilet is in of it's self an environmentally questionable means of handling human waste. It's not really waste after all. Dosing grey water with chlorine so we can send our crap into unhealthy anaerobic tanks, that drain into subterranean fields with less than ideal micro-flora is not all that progressive in my opinion.

    The heat recovery benefit is undeniable, and the fact that your system is effective for non-simultaneous uses (tubs, washers etc.) does give it a leg up on the gfx. Why is your water so cold?

    For a more extreme take on this have a look at this guy's setup:
    http://www.youtube.com/watch?v=F9XC7UoHQiE&amp;NR=1
  • Pumps, Chlorine, and Coooold Water

    The pump I used was recommended by the Grundfos rep, and it is a good fit for Grey Water Systems. It's workings are plastic, it is resistant to chlorine, it shuts off if the grey water tank runs out of water, and it's pretty quiet. The pressure switch is built in and it doesn't need a tank. The pump is a MQ3-35B and the model #96515512. Chlorine might not be a problem and Brac has a link on their website, to a clean water website that says adding chlorine to waste water before discharging into a river or stream is benificial because it kills harmful bacteria. The people that have septic or wells might not use this system If it hurts your septic. Or they might use UV to filter the greywater. The link is http://www.waterandhealth.org/wastewater/chlorination.php3 People are concerned about soap scum and bacteria in the tiolets, but I think toilets might be safer flushing with grey water. We know there is bacteria in the toilet already, I had one toilet that always got mold before I used grey water, if I didn't clean it often enough. With the added chlorine and or enzymes, the toilet is now mold free, and probably safer? I purposely haven't cleaned it for a while, and there is no sign of mold. It is a gray toilet and you can see a little white soap residue but I haven't cleaned the toilet for a couple of months. The white soap residue doesn't show on my white or almond colored toilets. Grey water systems are like any other renewable energy system, they should be used where they are most efficient and where they will do the most good with the shortest payback. Windmills work better in certain areas like up on a hill, you shouldn't put solar in if you have a lot of shade, and grey water systems should be used where there are water shortages, or high water and sewer bills, or for people with limited water in their wells. Grey water is the one system that works better in the winter, when solar give you the least hot water. My water is so cold because it comes from the Merrimack river which is fed by melting snow from further up north. I just checked it again and it is 37 degrees. It won't give me much of a pre heat in the summer the insoming cold water is about 70 degrees, I would be lucky to gain 10 of 15 degree pre heat, but I don't need it in the summer, the solar is cranking then. While the Grey Water System will pay back quicker in some areas, it could work virtually anywhere, except France.

    Thanks, Bob Gagnon

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  • Paul B_5
    Paul B_5 Member Posts: 60


    I'm somewhat interested in Brac as there is good potential there but all I want to say is babysitting this bacterial issue would probably get to me. Since I have 8 people in this house , my GFX has been performing very well for the past 8 years sight unseen with real good performance. Paul
  • Harold
    Harold Member Posts: 249


    As an alternative to chlorine injection, you could bubble ozone through the tank. This would sterilize without the residual chlorine smell. And treat even the gray water that overflows.

    This would be safer for septic systems. Ozone tends not to be persistent. An outside vent would probably be a good idea for this.
  • There is no babysitting

    Paul, even in my system I add chlorine only every month or two. The toilet water will smell a little when you flush, and tell you when to add chlorine, there is nothing to check. The chlorine tabs I use are from the pool store and about the size of a checker, they last a month or two. I imagine a slow dissolve chlorine tablet about the size of a hockey puck, might last 6 months or a year. But BRAC has a better system. I haven't seen it, but their web site says they have a Programmable Electronic Chlorination System. Maybe your water bills are not that high, but I pay $500 a year and people in surrounding towns, in the MWRA water district, pay $2000 plus yearly for water and sewer fees. For these people, and the people down in Florida and Georgia, with their water shortages, adding chlorine once in a while will probably be no big deal. You have to remember the GFX System only has heat recovery, the Grey Water System will also save around 40% of your water bill, that's huge. It's all about the water. Thanks, Bob Gagnon

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  • scott markle_2
    scott markle_2 Member Posts: 611
    water use

    Bob, how does toilet flushing account for 40% of water use? Correct me if I'm missing something. I can't imagine how 4 liters or so per person used to flush toilets could be 40% of consumption.

    The "if it's yellow let it mellow" policy could save considerable water, with no plumbing modifications. Small subset of people that will tolerate this though. One interesting thing about urine; it has more free nitrogen (plant nutrient) than feces and leaves the body essentially microbe free (sterile). I try to direct this waste "stream" to my compost pile when convenient.

  • Water use pie charts

    Every pie chart I see on water use in a home has toilet flushing at between 35% to 50% of total water use. The higher % might be for older houses that have toilets that use more water, not many houses have toilets that use 4 liters of water. I used to pratice the "yellow is mellow" method, but I think we will find flushing with clean grey water will be acceptable to a lot more people. Did you ever forget to flush a bowl full of urine overnight? It smells pretty bad. And it doesn't have any added chlorine.
    Thanks, Bob Gagnon

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  • bob eck
    bob eck Member Posts: 930


    Hi Bob Gagnon

    I have been following this tred does Brac Grey water systems make a unit for older homes that you can not separate the grey water from regular waste water?

  • No

    Not if you mean sewage. Couldn't you separate a bathtub, shower, or washing machine drain? You would have to. Sewage is too dirty and too expensive to clean up to reuse standards. Thanks, Bob Gagnon

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