Re: [OT] well, sort of. Central heating radiator plumbing

["James" <james@xxxxxxxxxxxxx>]

My understanding is that it is now "best practice" to
install an automatic
bypass valve in all new installations, particularly with a combi boiler.
Older systems tended to have an "always on" radiator (as already
described)
or a bypass loop.The  bypass loop is typically a 15mm "short
circuit"
between flow and return, with a ball valve to adjust the flow. The
advantage
of an automatic bypass valve over a bypass loop is that it is normally
closed, and progressively opens as the pressure increases when the rads are
turned off, so only shunts the heat as necessary, and doesn't produce any
"shock waves" when water is suddenly diverted through it.



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