drain water heat recovery

Daox · 09-22-08, 03:20 PM

Has anyone used or know about drain water heat recovery? I am incredibly interested and am most likely going to try this out.

http://gfxtechnology.com/

bennelson · 09-22-08, 03:39 PM

Hmmm - right on that web page, it shows a couple of installations and says where they are. Including one at a Dartmouth College Dorm.

Too bad we don't know anyone on this forum who is a Dartmouth student who could go take a look at it!

(And by this, I mean SVOboy. I did get the right school, didn't I?)

-Ben

Tony Raine · 09-22-08, 03:58 PM

huh, so its basically running your cold water through some copper pipe wrapped around a copper drain pipe from your shower?

good idea, and it sounds easy enough to build yourself........

Daox · 09-22-08, 04:55 PM

Quote:

Originally Posted by Tony Raine

good idea, and it sounds easy enough to build yourself........

Thats exactly my thought on it!

Since they install them vertically, the water going down the drain clings to the sides of the pipe creating a thin film and thus a great amount of surface area to sap the heat out of it.

Yeah, it would be nice if SVOboy could get us some actual info. He just moved back the other day.

dremd · 09-22-08, 08:09 PM

a buddy of mine has been talking about doing that forevor, must help . . . .

I bet it would be killer for a kitchen with a big dishwasher, or someplace like a dorm where there is heavy use per shower.

SVOboy · 09-23-08, 10:06 AM

I'll send out some emails to "the right people" and see if they can either tell me or connect me with someone in the sustainability office or facilities, operations, and management to talk about the heat recovery.

mopo3 · 09-27-08, 05:25 PM

I'm a chemical engineering student at georgia tech, and this is basically a simple energy balance. I have an excel sheet that you can use to calculate the economics.

spreadsheet (for calculations)
http://sites.google.com/site/showerh...attredirects=0

Diagram
http://sites.google.com/site/showerh...attredirects=0

Description (open in openoffice)
http://sites.google.com/site/showerh...attredirects=0

AC_Hacker · 10-10-09, 11:43 AM

Quote:

Originally Posted by mopo3

spreadsheet (for calculations)
http://sites.google.com/site/showerh...attredirects=0

Diagram
http://sites.google.com/site/showerh...attredirects=0

Description (open in openoffice)
http://sites.google.com/site/showerh...attredirects=0

Hey Mopo3,

Could you edit the open office 'description' link to contain a *.rtf, or a *.pdf, or a *.txt?

Regards,

-AC_Hacker

AC_Hacker · 10-10-09, 12:44 PM

I saw an interesting and stunningly simple shower heat recovery unit...

It used a coil of copper tubing which lay flat on the bottom of the shower, under a wooden grate.

Incoming cold water would run into the copper tube, get warmed by the shower water, then out to be mixed with hot water and on to the shower head.

I expect that there would be a brief period of temperature adjustment, until things stabilized, but, no massive drain replumbing, no serious problem with the heat recovery unit being fouled with shower mung. Just lift the grate and brush it off from time to time.

Using direct heat exchange has its limits because heat can only flow down hill, and the less the slope of the hill, the lower the rate of heat transfer. Things can be improved by using a vapor-compression device to, in effect, change the slope of the hill.

So, another direction for this discussion might be the use of a small re-purposed vapor-compression unit, such as those found in air conditioners, de-humidifiers, tiny refrigerators, etc, to extract heat from the drain water (COP > 4) and store it in an auxilliary water pre-heat tank, or a large super-insulated water tank, which would be a "thermal battery", or to send the heat into the ground via a polyethylene loop field, where it would, over time also act as a thermal battery.

There are companies in the USA making super-insulated water tanks, but their performance is well behind that of some of the European countries, where energy is 2x what it is here, and the expense of perpetual war is not draining the national economy.

I did some hasty calcs regarding how much water would be required in a water type thermal battery, to make a difference toward helping the heating of my small home (< 900 sq. ft.) and I figured it should be in the 500 to 1000 gallon size.

Once built, a thermal battery could store waste heat from a refrigerator/freezer, solar heat collector, recycled heat from domestic hot water, etc.

There was some work done on thermal water storage tanks at build it solar at this link and also at this link. And of course, there has been work done on building your own in-ground loop field for heat extraction and injection at this link.

Best Regards,

-AC_Hacker

%%%%%%%%%%%%%%%%%%%%%

Daox · 10-15-08, 09:55 AM

I just checked out your spreadsheet for calculations. What efficiency does the sheet use for the heat exchanger? There is a pretty large variance between the different models avaliable.

Here are also two more companies that make them.

RenewABILITY Energy, Inc.

ReTherm™ - Drain Water Heat Recovery Solutions

09-22-08, 03:20 PM	#1
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	drain water heat recovery Has anyone used or know about drain water heat recovery? I am incredibly interested and am most likely going to try this out. http://gfxtechnology.com/ __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

09-22-08, 03:39 PM	#2
bennelson Home-Wrecker Join Date: Sep 2008 Location: SE Wisconsin Posts: 546 Thanks: 3 Thanked 165 Times in 96 Posts	Hmmm - right on that web page, it shows a couple of installations and says where they are. Including one at a Dartmouth College Dorm. Too bad we don't know anyone on this forum who is a Dartmouth student who could go take a look at it! (And by this, I mean SVOboy. I did get the right school, didn't I?) -Ben __________________ To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

09-27-08, 05:25 PM	#7
mopo3 Oil Tycoon Join Date: Sep 2008 Location: Houston Posts: 1 Thanks: 0 Thanked 0 Times in 0 Posts	I'm a chemical engineering student at georgia tech, and this is basically a simple energy balance. I have an excel sheet that you can use to calculate the economics. spreadsheet (for calculations) http://sites.google.com/site/showerh...attredirects=0 Diagram http://sites.google.com/site/showerh...attredirects=0 Description (open in openoffice) http://sites.google.com/site/showerh...attredirects=0 __________________ ecomodder.com

10-10-09, 12:44 PM	#9
AC_Hacker Supreme EcoRenovator Join Date: Mar 2009 Location: Portland, OR Posts: 4,004 Thanks: 303 Thanked 723 Times in 534 Posts	Domestic Water Heat Recovery... I saw an interesting and stunningly simple shower heat recovery unit... It used a coil of copper tubing which lay flat on the bottom of the shower, under a wooden grate. Incoming cold water would run into the copper tube, get warmed by the shower water, then out to be mixed with hot water and on to the shower head. I expect that there would be a brief period of temperature adjustment, until things stabilized, but, no massive drain replumbing, no serious problem with the heat recovery unit being fouled with shower mung. Just lift the grate and brush it off from time to time. Using direct heat exchange has its limits because heat can only flow down hill, and the less the slope of the hill, the lower the rate of heat transfer. Things can be improved by using a vapor-compression device to, in effect, change the slope of the hill. So, another direction for this discussion might be the use of a small re-purposed vapor-compression unit, such as those found in air conditioners, de-humidifiers, tiny refrigerators, etc, to extract heat from the drain water (COP > 4) and store it in an auxilliary water pre-heat tank, or a large super-insulated water tank, which would be a "thermal battery", or to send the heat into the ground via a polyethylene loop field, where it would, over time also act as a thermal battery. There are companies in the USA making super-insulated water tanks, but their performance is well behind that of some of the European countries, where energy is 2x what it is here, and the expense of perpetual war is not draining the national economy. I did some hasty calcs regarding how much water would be required in a water type thermal battery, to make a difference toward helping the heating of my small home (< 900 sq. ft.) and I figured it should be in the 500 to 1000 gallon size. Once built, a thermal battery could store waste heat from a refrigerator/freezer, solar heat collector, recycled heat from domestic hot water, etc. There was some work done on thermal water storage tanks at build it solar at this link and also at this link. And of course, there has been work done on building your own in-ground loop field for heat extraction and injection at this link. Best Regards, -AC_Hacker %%%%%%%%%%%%%%%%%%%%%

10-15-08, 09:55 AM	#10
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	I just checked out your spreadsheet for calculations. What efficiency does the sheet use for the heat exchanger? There is a pretty large variance between the different models avaliable. Here are also two more companies that make them. RenewABILITY Energy, Inc. ReTherm™ - Drain Water Heat Recovery Solutions __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

09-22-08, 03:58 PM	#3
Tony Raine Helper EcoRenovator Join Date: Sep 2008 Posts: 57 Thanks: 0 Thanked 0 Times in 0 Posts	huh, so its basically running your cold water through some copper pipe wrapped around a copper drain pipe from your shower? good idea, and it sounds easy enough to build yourself........

09-22-08, 08:09 PM	#5
dremd Need More Eco Join Date: Sep 2008 Location: Scott, La Posts: 172 Thanks: 2 Thanked 6 Times in 6 Posts	a buddy of mine has been talking about doing that forevor, must help . . . . I bet it would be killer for a kitchen with a big dishwasher, or someplace like a dorm where there is heavy use per shower.

09-23-08, 10:06 AM	#6
SVOboy Administrator Join Date: Aug 2008 Posts: 291 Thanks: 3 Thanked 4 Times in 4 Posts	I'll send out some emails to "the right people" and see if they can either tell me or connect me with someone in the sustainability office or facilities, operations, and management to talk about the heat recovery.