DIY Grey Water Heat Recycling...
 

There is an interesting entry in Wikipedia on Water Heat Recycling.

This photo is shown:


The article states:

It seems to me that someone could duplicate such a device for much less than $500 to $1000, and the payback would be much shorter.

I also found that there is a company called GFX Technology that makes such a device. They have a PDF of performance curves located here.

There's even a Bob Villa video Bob Villa video available here.

Here are other companies in the same business:

http://www.renewability.com/powerpipe.htm

http://www.retherm.com/

http://www.ecodrain.ca/

The important features I can see are:
* counter-flow - drain water goes in one direction, incoming cold water goes in the opposite direction (larger 'delta-T', makes the efficiency higher.)
* drain water flows in a thin film inside the heat exchanger - this assures maximum exposure of the hot drain water to the cold incoming water, making the efficiency higher. (question: is a special structure required for this to happen?)
*copper construction assures good heat transfer. (question: is the coil soldered to the drain water pipe?
* it also seems to me that encasing the whole assembly in insulating foam would improve the efficiency even more.

I have seen projects where plastic 55 gallon barrels and long pieces of PEX are coiled inside to make such a system, but this compact copper unit seems to be elegant, compact efficient and highly buildable.

Here are more photos of the GFX units:


With domestic water heating being the second biggest energy use for homeowners, this seems to be a natural target for our efforts.

Claims of efficiency seem to run as high as 50%, this would hold for fossil fuel use, and also for wood water heating, as well as for the size of a solar Domestic Hot Water (AKA: DHW) array required to supply DHW to a home or business.

Best of all, no moving parts.

Build It Solar has a relevant link here.

Here is a link to a Grey Water Heat Recovery Calculator.

Are the wheels turning?

Regards,

-AC_Hacker

One would think the coils should be insulated, if the basement air temp is low.
Today, the air temp in my basement isn't much warmer than the incoming city water.

But, if your basement was heated, that coil is going to be warmed up to room temp after a while. So, insulation wouldn't be so good.

Nope, this the natural way water flows through a vertical pipe.


Definitely.



I'm a huge fan of these devices and think everyone should have one. The bad news for me is my sewer drain is over half way up my basement wall. So, I don't have much vertical drop to splice one in...

The bad news for me is my sewer drain is over half way up my basement wall. So, I don't have much vertical drop to splice one in...

I have the same problem. Plus, the area where we make the hot water
is half way across and on the other side of the basement.

However, I think this idea might be workable by using a short unit
fed from the tub drain which is about a yard above the lowest input
to the sewer plumbing.

My tub is Very close to being right on top of the main sewer exit pipe.

If I could install a short (fat?) 24" unit in the shower drain line, and reroute
the cold water going to the tub, I could take the chill out of the cold water,
making it possible to use less hot water from the boiler.. :D

I would insulate the exchanger, fer sure..

Edit: Saw this..
Trimline Design Centre: Watercycles HX-3030
That HX-3030 looks petty simple to make.

According to what my old moonshiner Grandpa from NC told me, one could make
a copper tube coil by filling the tubing with sand. Use wood plugs in each end
and the hard-packed sand would allow the tube to bend without kinks..

So, maybe using a dowel that was a bit smaller than the large copper drain pipe,
I could make a nice tight coil around it, then force the coil onto the drain pipe.?.
Insulate the whole thing and plug-n-play!

This is really starting to sound like a good DIY project! :D

Hello Ben, (If you are around)
I'm thinking of stealing your design and hacking it!
http://farm3.static.flickr.com/2667/...4da7968be2.jpg
I'm daydreaming of a horizontally mounted Shower Waste Water Heat Recovery heat exchanger.
(On the ceiling of the laundry room).

Since the waste water is at near zero PSI, and I want keep the heat inside,
and make it cheap.. How about using 2" or 3" PVC for the water-jacket?

I would attach a 2" PVC flex hose to my tub drain, connect it to the SWWHR
input and drop the waste output with another flex hose into the washing machine drain pipe.

The trick would be sealing the 1/2 copper cold water pipe (L type) in the center of the end caps.
Since the gray water has such low pressure, it might not be a big problem.
Perhaps the copper supply pipe need not be in the center.?.
Maybe it can be positioned near the bottom of the PVC, to insure it's completely covered by the flowing waste water..

The PVC tube would be about 4 or 5 feet long and not quite level,
so it will fill up with gray water, before pouring out the higher end.
Insulate it well and start using less oil to heat my shower water!

Edit:
Someone invented the PVC version. Saw it on Ebay.

Waste water Heat exchanger Water Heater Green Energy - eBay (item 170390818624 end time Apr-02-10 19:06:03 PDT)

Xringer's Daydream...
 

This sounds like a great idea. I have the same problem with the waste line being too high to use the GTX configuration.

Some possible problems I can think of...

* Expansion differences between copper pipe & PVC could prove difficult to seal. Do you know what the thermal expansion index is of PVC & copper?

* A very good feature of the GTX configuration is that the waste water falls straight down and 'scours' the surface of the exchanger pipe. So, on a more horizontal configuration, you may want to allow for clean-out ports as are built into many ABS elbows & sink traps.

Overall, the PVC/copper combo could be a real cost-effective plan.

Regards,

-AC_Hacker

You can do this set up right at the shower drain, or at the dishwasher drain, and get a little more heat than at the waste invert.

Also, you if can do a heat pump exchange in the sewerpipe:
http://img.photobucket.com/albums/v7...werHeat-01.png
then you can heat a home with as little as 5' of sewer pipe.

thermal expansion? dang!
 

http://www.homedepot.com/catalog/pro...b80f9c_300.jpg

DBHL No. HD7983c, 1-1/2 In. x 3/4 In. Flexible Rubber Coupling
Model # HD7983C Store SKU # 316954 $3.39/EA-Each

Maybe a couple of these boots on some PVC reduced down to a 1.5" OD,
and use a 3/4" copper pipe down the center? (I have 3/4 'L' in stock).


It's kinda funny looking up at the 'temporary' drain I installed on the
bottom of our pretty new FG tub back in the late 70s..
My wife demanded we replace the old iron tub. It was the wrong color. Pink!
The tiles around the tub had been leaking since,, maybe 1956? When the house was built.
A blue three section FG wrap-around wall with matching tub was her choice.

The new tub drain was in the wrong place and I needed an off-set drain connection..
I went down to the nearby auto-supply store and got some radiator hose and SS clamps.

The hose and clamps still look dang good. :D

http://i46.photobucket.com/albums/f1...Solar/r051.jpg

I'll bet you guys have never seen polybutylene pipes and fittings that lasted over 25 years! :eek:

The only one that dissolved was on the hot water side, where water leaked
out of the tub faucet and ran down the outside of the screw-in fitting.
It seems to be the mix of air and water on the outside that eats them.

I just changed out the old tub faucets last week. The new ones look great.
I had to get rid of the upper pipe to the shower head (all polybutylene),
because I broke it while screwing in the new shower head!
Replaced it with PEX and quick-PEX fittings. Not knowing they can't hack
very high temperatures.. Read the specs after installation.. :eek:

You do want the tube to crush up against the main drainage line. This provides more contact surface area and thus better efficiency.

New guy wading in
 

Been lurking for a bit, time to get in. You guys have some really good stuff here, especially for the "think outside the box" type of DIY.

These are 'thin film/falling film' exchangers, we use these types(plate/fin) in cryogenics, they are the most efficient design. Although to be such it needs to have 'intimate'(ha-ha)contact on the same wall.

I want to do a modded version, cu drain thru the middle, supply thru next larger cu pipe outside, pressurized, providing 'intimate' contact for best transfer. This would also work pretty well horizontal, which I need 1 of.
Just like Xringer/Ben's pic, only 2/3'' pipe.

I just need to get it done, and have some faith in my sweat abilities. I shouldn't 'sweat' it, I plumbed my whole house with no leaks. Yet!

Ya'll have a good day, I got to get to the grind. I'll check in time to time.

Tim

Welcome aboard Tim..
It sounds like you have been on the DIY boat for a while.
I don't like doing plumbing, but the alternative is what motivates me to keep trying.
I've had 'expert' plumbers really drop the ball and what they charged me (high priced),
was nothing compared to the cost of hiring a welder to come in and repair my
poorly installed boiler.

So, my hats off to you for your 'no leaks' record. May it always stand!

About 20 minutes ago, my wife yelled from the kitchen, 'You've got water in here'!
I was in a panic! Was it the new food disposal, or the new sink faucets??
For an old guy, I got into the kitchen pretty fast. Where's the water??
She pointed and said, "it's in the microwave"!
I was dumbfounded for a couple of seconds, wondering HOW this could have happened!
Then, I realized she was referring to coffee cup of water I had just warmed up in the micro!!
It was done.. It was starting to cool off.. LOL!!
She was yelling because I've recently had a sudden-hearing-loss problem..

It sinks getting old!

Cheers,
Rich

I think my city sewer pipe is about 20 feet under the street..
But, I'm wondering if there is warm air inside that long downhill run
of PVC going to the street??
I have a 90 degree turn inside a man-hole beside the house in the back yard.
I could dig up the cover and scan it for heat!
It might not be too hard to drop a folded back line down into that PVC..
Haha! digging down to a BTU mine..

I can just picture a couple of 80 foot PEX lines with an exchanger payload
on the end, slowly descending downwards towards that warm city sewerage.. :p

I wonder if one of those Ebay flat plate exchanger would work for a shower drain (warming the cold input side).

50 Plate Outdoor Wood Furnace Heat Exchanger 1-1/4"Port - eBay (item 250586847892 end time Mar-26-10 22:34:19 PDT)

Might be a little tight in there..
http://flatplateheatexchanger.com/im...at_plate_1.jpg
Have to build in a back-flush valve to clean it out.. :(

Yeah, I don't think that would work well at all. The clearance between plates is very small on those. It would get clogged rather quickly I think.

I was picturing hair-balls and how to filter them before they got to the filter.. :eek:

A screen filter on the gray input and a back-flow valve might be advisable on any kind of exchanger..

EBay Crazy
 

Domestic Hot Water Heat Exchanger/Recover Green! $ave! - eBay (item 270311034829 end time Mar-25-10 18:03:33 PDT)


http://www.frost-farms.com/h-exch%20enter.jpg

Those Ebay guys might be getting into the DIY mode..?.


http://www.frost-farms.com/h-exch1.png

Not a horrible idea (horribly overpriced though!). But not nearly as efficient as the vertical versions.

Yeah, the price is NOT right..

But the 'idea' looks like someone has been surfing these postings! :thumbup:

I have to admit, my vision of the PVC unit had the gray water in the outer jacket.
Since it's at such low pressure, there would be minimal risk of a flooded basement.

I just believe in keeping the 70 PSI (plus Hammer peaks) city water inside of some good old copper.. :D

As to price, it's really not so bad, even with shipping. Now, that's not to say we can't build it cheaper.

I rather like the idea of having the copper for the waste line, the larger diameter and straight-through design would be less likely to foul and if clean-out were called for, it would be easier to do.

As Xringer intimated, I'm wondering if the pressure couplings on the water jacket would hold up to city water + hammer pressure.

Although I think it's overkill, many states will not accept a heat exchanger that carries domestic water unless it's double-wall construction, which this device is not. The GTX device is.

And I think this guy is missing the boat, in that if he oriented it vertically, it would equal or beat the efficiency of the vertical tube & coil heat exchangers, since ALL the surface of the waste line would be heat-passing area... EAGRAHAM, are you listening?

But I think it is a very good sign that someone, whether they mined the idea from Ecorenovator or not, is actually doing it... He actually put the idea into action and is offering it for sale at a reasonable price.

An aside to eagraham:
But, all-in-all, he has shown us how to build it.

Regards,

-AC_Hacker

On a larger scale, in Sweden heat is recovered from waste treatment plants and used for district heating. The temperature of water leaving the sewage treatment plant is between 7-22*C, large heat pumps extract heat, cooling it to 1*C before it is dumped into the sea. This can cover as much as 10% of a city's heating needs.

See the links at the bottom of my post Sweden - Oil independance through conservation and efficiency

Today, (April 10, 2010) I got a reply about this Ebay item..


I apologize for the late response but our home burned down. The unit is designed for shower / tub drains, it is 18" long 1.5" drain in and out and 3/4 lines for inlets and outlets. The units is assembles from copper and is soldered. Unit is sealed in PVC and filled with foam to retain the heat. I have tested the units to 80 psi for city water pressure but not higher, I do believe they would hold 100 psi. The flow rate at 60 psi is 4.5 gpm.

- davee4089

Making a Copper Coil...
 

Here is a scan from a book that is no longer in print:


...the picture tells the story.

The coil shown in the photo is meant to go into a chimney pipe for heat recovery, so the precise internal and external dimensions are not so critical. If the coil was intended to wrap around a waste pipe for heat recovery, the internal diameter of the coil would be critical. When wrapping such a coil, a certain amount of "spring-back" will occur, so some experimentation would be required to make a mandrel (a log in the picture) of such a diameter so that contact between the formed coil and the copper waste water pipe would happen. Then, soldering would really improve the situation.


Regards,

-AC_Hacker

I have a good commercial unit, and on inspection can see the copper water pipe was soldered to the copper drain pipe before starting the coil. It was wound so tight, the 1/2" copper looks pressed - with squared edges for extremely tight contact.

Another embodiment
sdinfo.ru/waste-water-heat-recovery

necro-ing, because 1/2 copper tubing was on clearance at my local Lowe's for $1.79. Just need to find some cheap copper DWV now.

Don't have enough posts for the link, search for "1/2-in dia x 20-ft L Copper L Coil" to check yours. Was only that price at one store, so ymmv.

Here was my take on it.
http://ecorenovator.org/forum/conser...exchanger.html