14
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S
HEET
M
ETAL
/HVAC
P
RO
C
ALC
FAN LAW KEYS
Your calculator also has built-in formulas and keys that calculate Fan
Laws 1, 2 and 3, for air flow calculations. Each of these formulas
requires the entry of three variables in order to solve the fourth.
Ç R
Fan Law 1
— Calculates the missing variable (e.g.,
“a-new” or “b-new” for CFM new or RPM new) for
Fan Law 1, given the three known variables into the
applicable Storage Registers (see below). See
page 75
for examples.
Ç r
Fan Law 2
— Calculates the missing variable (e.g.,
“a-new” or “b-new” for CFM new or SP new) for Fan
Law 2, given the three known variables into the
applicable Storage Registers (see below). See
page 76
for examples.
Ç d
Fan Law 3
— Calculates the missing variable (e.g.,
“a-new” or “b-new” for CFM new or BHP new) for
Fan Law 3, given the three known variables into the
applicable Storage Registers (see below). See
page 77
for examples.
Storage Registers Used For Fan Laws:
Ç 4
Storage Register “a”
— Enters “a-old” or current
“a” value.
Ç 7
Storage Register “a-new”
— Enters “a-new” or
new “a” value.
Ç 5
Storage Register “b”
— Enters “b-old” or current
“b” value.
Ç 8
Storage Register “b-new”
— Enters “b-new” or
new “b” value.
