Working on a previously healthy 4 port manifold radiant system. The
thermostatic part of the system seems to be working... the pump
(Grundfos UP 15-42F) & boiler (shows 140) come on & the motoroized
The mystery is that only 2 zones (closest to the boiler input end of
the manifold) get flow (both input & return tubes heat up)... even when
manual depressing the
actuator valve, there is no discernable heat in either of the other 2
manifold & actuators were new 6 months ago and it is reported that
everything worked fine, until recently.
What could have happened that would cause these 2 zones to not flow????
Any thoughts greatly appreciated.
Thanks for all the responses... the culprit here was a huge amount of
calcium buildup and corrision... the two bad loop's manifold valves
were completely eaten apart, that is, the shaft was no long connected
to the closing seal... so, up or down, nothing was happening as far as
opening or closing the circuit. Should have checked that earlier, but
this was a new manifold installed just 8 months ago.
That solved, the question remains as to why so very much corrosion in
such a short period of time...????
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