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or where the expansion vessel is in close
proximity to the solar collector.
It is particularly important that an
intermediate vessel is installed on systems
where the volume of the collectors exceeds
the volume within the flow and return
pipework. This is because during stagnation
periods, the very hot solar fluid in the
collectors can reach vaporisation point. If this
occurs, the very hot solar fluid is forced out
by the vapour, into the expansion vessel.
Intermediate vessels have inlet/outlet
connections and are installed just before the
main expansion vessel (as shown above). The
heat sink that the intermediate vessel
provides, reduces the working temperature
at the diaphragm, and hence considerably
extends the working life of the expansion
vessel.
