wrote:
Solar Flare wrote:


Well the efficiency of heat exchange factor is not the only
efficiency. A purchased and installed product at 5% efficiency is much
more economical than a well designed, thought out, project that will
be implemented sometime after getting a 'Round Tuit


Le mieux est l'ennemi du bien. I'm better at thinking up things
than getting round tuits.


Efficiency of installation ease.
Efficiency of installation time.
Efficiency of product parts and pieces aquisition


I can relate to that, having spent about 40 hours in the last 2 weeks
visiting various plumbing supply stores. It's been fun learning names
of fittings, like "bullnose T" and "Dismukes crampon lifter."


Efficiency of marriage after the home space displacement.


Spouses care a lot more about what's on the lawn
or in the living room than what's in the basement.


Your spouse maybe, lots of others may diagree.
Efficiency of trial and error costs.


It might be nice to build more than one, with careful directions at
http://BuildItSolar.com


Efficiency of maintenance.


And only empty the crud once a year, using a hose instead of a toothbrush.


GFX need NO cleaning EVER, even when hooked to WHOLE house SEWER.

If you wanted to clean a GFX, its simple to remove and HOSE it down
also, but there is no need to do so.

Yours WILL need interior cleaning
Efficiency of computer time arguing about imaginary issues.


Some issues are more important than others, eg daestrom's.


Efficiency of home resale after the newfangled frankenstein
paraphenalia is seen.


This leads me to make things easy to remove.


"Robert Gammon" wrote:


Solar Flare wrote:

GFX nick
efficiency 6 7
price 5 3
convenience 9 1
wife likes 6 0
----------------------
total score 26 11


GREAT scoring system.


Nah. Efficiency should be 8 vs 7, a lower price should give me more
vs fewer points, convenience is TBD, and wives may like saving more
money, or having more to spend in other directions.

20 UPIPE=78.5'U-value of 10' section of pipe (Btu/h-F)
30 CFRESH=1.25*8.33'thermal capacitance of 10' of fresh water (Btu/F)
40 VGREY=10*3.14159*(2/12)^2'volume of 10' of greywater (ft^3)
50 CGREY=VGREY*62.33-CFRESH'thermal capacitance of 10' of greywater (Btu/F)
60 FOR SHOWER = 1 TO 1000'simulate showers
70 FOR M=0 TO 359'simulate 10 min shower + 350 min rest
80 IF M9 GOTO 200'rest vs shower
90 IF SHOWER 1000 GOTO 120
100 RHEAT=RHEAT+1.25*8.33*(100-TF(0))'reheat energy
105 GLOSS=GLOSS+1.25*8.33*(TG(9)-55)'greywater heat loss
110 PRINT 300+M;"'";M,TF(0),RHEAT,TG(9),GLOSS
120 TF(0)=TF(1)'move fresh water up
130 TG(0)=(100*CFRESH+TG(0)*(CGREY-CFRESH))/CGREY'move greywater in at the top
140 FOR S=1 TO 8'pipe section (9-fresh water in and greywater out)
150 TF(S)=TF(S+1)'move fresh water up
160 TG(S)=(TG(S-1)*CFRESH+TG(S)*(CGREY-CFRESH))/CGREY'move greywater down
170 NEXT S
180 TF(9)=55'move cold water in at the bottom
190 TG(9)=(TG(8)*CFRESH+TG(9)*(CGREY-CFRESH))/CGREY'move greywater down
200 FOR S=0 TO 9'rest
210 HEATFLOW=(TG(S)-TF(S))*UPIPE/60'heatflow into fresh water (Btu)
220 TF(S)=TF(S)+HEATFLOW/CFRESH'new fresh temp (F)
230 TG(S)=TG(S)-HEATFLOW/CGREY'new grey temp (F)
240 NEXT S
250 NEXT M
260 NEXT SHOWER
280 SHOWERGY=1.25*10*8.33*(100-55)
290 PRINT RHEAT,SHOWERGY,1-RHEAT/SHOWERGY

0 94.56091 56.6345 71.68895 173.7736
1 92.93514 130.1973 72.0242 351.0381
2 91.38136 219.9389 72.44145 532.6472
3 89.96538 324.4244 72.83433 718.3472
4 88.72086 441.8685 73.20448 907.9012
5 87.6472 570.492 73.55341 1101.089
6 86.72784 708.6885 73.88255 1297.703
7 85.94302 855.0568 74.19321 1497.553
8 85.27464 1008.385 74.4866 1700.457
9 84.70704 1167.623 74.76389 1906.248

1167.623 4685.625 .7508075

This is confusing. The greywater output seems to warm during the course of
a shower, but I wouldn't expect that in a real system with 100' of 4" pipe.



This stands to reason that greywater output will rise in temp inyour
heat exchanger as the time required to recapture the heat exceeds the
amount of time that the greywater remains in the heat exchanger. Need
higher surface area (i.e. longer, or larger diameter tubes).