The one pipe (Figure 3) system utilizes
one main pipe that connects from the boiler
supply to the boiler return. The heat emitter is
connected to the main by two smaller (feed and
return) pipes that are fitted with diverter (aka
Mono-flow, Venturi, Jet, or One pipe) tees that
cause a portion of the water circulating in the
main to be routed through each section of the
attached emitters. Typically, one standard tee
and one diverter tee are used for each emitter
unit. It is important to follow the manufacturer’s
instructions regarding the spacing between
the tees and which pipe (feed or return) to
install the diverter tee on.
Sometimes it is necessary to provide two
mono-flow tees for a single heat emitter to produce
sufficient water flow through that radiation.
For example, if a radiator is lower than
the main pipe, the buoyancy effect of the cold
water at the bottom and hot water at the top
will cause insufficient flow. In this situation,
two diverter tees must be used and the spacing
between them should be the same as the width
of the heat emitter. Figure 4.
Another situation where two diverter tees
may be needed is when a radiator has been removed
and replaced with baseboard heating. In
those situations, the diverter tees can be relocated
to compensate for the additional pressure
drop through the baseboard or an additional
diverter tee can replace the standard tee. Figure
5 on following page.
16 National Oilheat Research Alliance
Figure 4
Figure 3