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post #516 of (permalink) Old 10-16-2011, 08:32 PM Thread Starter
Wannabe Guru
DKShrimporium's Avatar
Join Date: Nov 2004
Location: PA/MD/DE tristate area
Posts: 1,413
Heat exchanger is IN and LIVE inline!

...And... DK is pretty tired. (See pictures this post and the next post.)

The goal of the project is to knock the chill off the incoming winter well water, which can enter the system in the 50s temp-wise. This is not a maximized system by any means, but hopefully will alleviate super-cold water entering the tanks and causing all the heaters to actuate at once.

Basic scheme is input water for the Water Factory enters a coil at the bottom of the waste water barrel. The coil spirals up toward the top of the barrel, then continues into the Water Factory.

Waste water from the tanks (warm) enters the BOTTOM of the barrel (it is routed through the blue discharge hose you see here), fills up the coil space, overflows into the central bucket, fills central bucket until sump is triggered. The coils are always under water, and always get the warmest water, in theory.

The large PVC rings under the central bucket provide some dead space and residual water at the bottom of the coil barrel.

The hepex tubing (red) is coiled around with clothesline for spacer, so there is water space between loops of the hepex coil. Not elegant, but it was cheap, easy, and got the job done. If you've ever worked with pex tubing, you know it has a mind of its own, so you end up fighting it, and hepex is even worse - more rigid and stiff, and with more memory than regular pex tubing. I had to fight every **** level of coil into the barrel. I gave myself a break, though, and splurged on the $10 pex tubing cutter with ratchet... so glad I did. Much trickier than it looks to wrap this hepex with clothesline and coil it into the barrel, believe me. I knew it was going to be a fight, so rested up between projects to do it.

Hepex tubing is not nearly as efficient at heat transfer as standard heat exchanger coils, which are typically super-heat-conducting copper. We cannot use copper, or metals! Hepex is better at heat transfer than pex, which is basically an insulator. Hepex was designed for use in radiant heat flooring, driveway melters, etc. The big advantages are cost and inert composition.

By the way, I found the hepex on clearance online, got it about half price, so that made DK happy.


Last edited by DKShrimporium; 02-25-2013 at 03:05 PM.
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