Retrotec USACE - Manual (Page 162)

D32 ENERGY & PROCESS ASSESSMENT PROTOCOL
D.2.3.3 Loose Fan Belts (Ineffi ciency)
Figure D53. Fan belts attached to pulley on
fan.
Fan belts are used to connect electric motors with fans to achieve air fl ow in an
HVAC system (Figure D53). They transfer energy from the motor to the fan
and allow the system to operate properly. When the belts become loose, there
is a loss of energy and loss of air fl ow. In addition, loose belts can harm the shaft
on the motor or fan wheel.
D.2.3.4 Duct Air Leaks (Waste)
Figure D54. Section of supple air duct in
mechanical room that has come loose,
creating a large duct leak.
Air leaks in duct systems can occur in the supply and return ducts. Leakage
rates of 10–20% are not uncommon. Duct leaks are especially wasteful when
the leaks occur in ducts passing through unconditioned spaces (Figure D54).
When they are present in the supply duct, energy is wasted, since not all the
air conditioned by the supply air unit is reaching the spaces being served. This
air could be escaping into unconditioned spaces such as attics or into condi-
tioned spaces, which would be overventilated. Leaks in the return duct could
result in excessive unconditioned air being delivered to the air handling unit,
causing more energy use for heating and cooling. A duct leak can also cause an
unbalanced condition between the supply and exhaust from a space. Leaks in
the supply air duct could cause an underpressurization of the space, resulting
in infi ltration of outdoor air.