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I’ve found 3 recommended ways to run pipes for a
WH-fired radiant system. Radiantec shows the least
convoluted way: incoming cold water is routed
through your heated zone first, then returned to
WH via drain valve. Hot water is supplied first to
general fixtures then to same incoming line, with
a check valve in between. The normal cold water
inlet is apparently just capped. (It seems counter-intuitive
to run cold water through heat line, but it insures you
won’t ever have stagnant water anywhere.)
An article in jlc shows a more convoluted method,
and the manual that came with the WH shows a Rube
Goldberg masterpiece. jlc shows an expansion tank;
neither of the others does. My plumber recommends
a check valve on incoming cold water line; none of
the other three does.
Is there a good discussion, somewhere, of the best
way?
