[AC_Hacker]

I have a book here, written by a radiant heating guy that worked in the New England area. As I recall, he is retired now.

His experience went all the way back to the days of iron pipes buried in cement. An he actually had a significant part of a chapter on black sludge. In his view it was an excellent sign, because it indicated that the active elements in the circulatory part of the radiant system were as reacted as they were going to get. In fact he commented on the foolishness of inexperienced workers who wanted to flush and replace all the beautiful black stuff, which set up a situation such that the chemical reactions would re-commence.

I tell you, stories like that give me nightmares.

Please tell me that we have come farther than that.

I have studied some papers that looked at the role that fouling plays in the efficiency of brazed plate heat exchangers, of which I am so very fond. They even had some formulas that calculated the rate of fouling over time and the subsequent loss of efficiency.

Of course, in an open loop system fouling was nearly uncontrollable, save what particulate could be filtered out, but dissolved minerals would get through most filters.

In closed loop systems, the fouling rate was more controllable and could be reduced through PH control, etc.

The most interesting part of the paper was that by using distilled water, fouling could be reduced to a vanishingly small fraction. I mean, most women that I know would never think of putting tap water in their steam irons... Could they be that smart?

So, how about in-line filters? Nobody has mentioned in-line filters. They do exist. Are they just another gizmo?

-AC