|03-01-10, 11:49 AM||#1|
Join Date: Mar 2009
Location: Portland, OR
Thanked 707 Times in 529 Posts
DIY Grey Water Heat Recycling...
There is an interesting entry in Wikipedia on Water Heat Recycling.
This photo is shown:
The article states:
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
Here are other companies in the same business:
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?
Last edited by AC_Hacker; 03-01-10 at 11:51 AM..