Hybrid Car – More Fun with Less Gas

Re: Recuperate some of the heat from a group of showers - Page 4

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Posted by daestrom on September 3, 2007, 3:46 pm

Why not just a 1" external pipe cap with a hole for the 3/4 pipe to extend
out from?  ISTM that it would be easier to seal around the 3/4 pipe in the 1
inch cap than to build up with tape.  With the 3/4 pipe extending out a
short way, you can then do all sorts of things to attach the garden-hose

P.S.  Sorry, my ASCII-art skills are no where up to yours, you'll have to
try and picture what I mean :-)

Posted by nicksanspam on September 3, 2007, 4:08 pm

This may be a matter of taste. To me, the tape (less than 1/16") seems easier,
(maybe something instead of electrical tape?) even with low-pressure greywater,
and I've never seen a PE (black water pipe) cap, except the ones on the ends
of new rolls to keep them clean.

Neon and I like vi. My Berkeley friend Dave says "We're all unix out here."


Posted by daestrom on September 3, 2007, 8:11 pm

vi??? BAH!!! a poor second to emacs.

(text editors are like politics, best not discussed at the dinner table :-)


Posted by nicksanspam on September 4, 2007, 7:24 pm
Well, 3/4" pipe turned out to be a very tight fit, so I decided to use
1/2" PE pipe inside 1" PE pipe, with a 1/2" fpt to 3/4" mpt PVC bushing.


Posted by nicksanspam on September 3, 2007, 3:45 pm
 A garden hose connection might backflush the outer tubing and upper drum
automatically, with a solenoid valve from a dead washing machine and a $
hose bibb vacuum breaker that closes the tubing outlet and opens the hose
connection behind it for 10 minutes when the upper drum is full too often,
eg when an upper-drum float switch has been open a long time.

If the basement is 70 F and the switch heats a 1-quart water bottle with
12V 82 and 91 ohm 1 W resistors glued to the bottom, inside a 6"x6"x1' R20
box with conductance G = 2.5ft^2/R20 = 0.125 Btu/h-F, the final temp will
be 161 F. With the upper drum always full and RC = 2/0.125 = 16 hours,
the bottle will reach 140 F in -16ln((140-161)/(70-161)) = 23 hours.

An $ Grainger 2E248 snap disk thermostat on the other side of a 6"x6"
R5 wall between the thermostat and the bottle could open the backflush
solenoid when it reaches 140 F and close it when it the thermostat reaches
120 F. A 33K 1/2 W hysteresis resistor could keep the thermostat closed
with 3.412x120^2/33K = 1.49 Btu/h of heat until the bottle temp drops to
120-1.49R5/0.25ft^2 = 90 F.

A rubber stopper with 2 tubes in the bottleneck might move P pounds of 60 F
backflush water into the 140 F water, so the bottle temp reachs 90 F when
(60P+(140(2-P)/2 = 90, ie P = 0.8. If this takes 10 minutes, 0.8/(10x8.33)
= 0.0096 gpm would flow through the tubes.


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