12
INSTALLATION
Hydraulic Resistance of Fittings, Valves,
and Other Devices
Before the total hydraulic resistance of a piping circuit can
be found, the individual hydraulic resistances of all fittings,
valves, or other such components must be determined.
One approach is to consider each fitting, valve, or other
device as an equivalent length of copper tube of the same
pipe size (see Table 2).
By using the equivalent length of piping for all components
in the circuit, the circuit can be treated as if it were a
single piece of pipe having a length equal to the sum of
the actual pipe length, the total equivalent lengths of all
fittings, valves, or other devices. Refer to Figure 10 and
the calculation of equivalent lengths.
Pipe Sizing Considerations
At water flow velocities of approximately 2 feet per second,
flowing water will carry air bubbles along a vertical pipe.
Average flow velocities of 2 feet per second or higher can
draw along air bubbles in a downward flow. At the above
stated velocities, air bubbles shall be routed to an air
separator where they can be collected and discharged
from the system. Use Taco 4900 series air separator,
Model 49-075, or equivalent (field supplied).
Average flow velocities higher than 4 feet per second could
cause flow noise and should be avoided.
Expansion Tanks
All liquids used in hydronic heating systems expand
when heated. For all practical purposes, liquids are
incompressible. Any container completely filled with a
liquid and sealed from the atmosphere will experience
a rapid increase in pressure as the liquid is heated.
To prevent this from occurring, all closed loop hydronic
systems MUST be equipped with an expansion tank.
Refer to expansion tank manufacture’s instructions for
proper sizing and installation.
R E D Z O N E
T M
D V S S E R I E S A I R H A N D L E R M A N U A L
