No, I haven't seen them for years.



The bi-flow valves had a balancing valve incorporated.
You removed a cap and the was a slot headed screw needle valve to do
the balancing.

I used them in my parents house, must have been the mid/late 60's.
I used copper pipe, the was no plastic back then

There was no screw on my parents'. The whole system was designed to be
balanced by design, hence the multitude of different pipe sizes
available.

SteveW




My house was built in 1988 and used them (Maxitwin). Other houses in the
road had conventional ones so I think I was having left over ones used.
Ihad no probelems but eventually when Thermostatic valves were mandated at
bliler change I had them swopped. One pipe was taken behing the radiator to
the other end.