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Hydronic Formulas

Pump Law #1

=

old

new

old

new

RPM

RPM

GPM

GPM

Formulas for problem solvingRPM is interchangeable for GPM

Note: newis the same as 1 and oldis the same as 2

GPM new = GPM old X

old

new

RPM

RPM RPM new = RPM old X

old

new

GPM

GPM

Pump Law #2

2

old

new

GPM

GPM=

old

new

P

Por

old

new

GPM

GPM=

old

new

P

P

Formulas for problem solving

GPM new = GPM old xold

new

SP

SP SP new =

2

old

new

GPM

GPM

Pump Law #3RPM is interchangeable for GPM

3

old

new

GPM

GPM=

old

new

BHP

BHPor

old

new

GPM

GPM= 3

old

new

BHP

BHP

Formulas for problem solving

GPM new = GPM old X 3old

new

BHP

BHP BHP new = BHP old x

3

old

new

GPM

GPM

Hydronic Thermal Calculation:

)(500 WaterT

BTUHGPM

=

BTUH GPM T = 500

TBTUH

GPM=

500

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2

)()(

=

GPMold

GPMnewxpsiPoldpsiPnew

GPM = Cv x ( )psiP Cv =( )psiP

GPM

2

=

Cv

GPMP

Water: sp.ht. = 1.00.12 gal. = 1lb.

8.33 lbs. = 1 gal.

8.33 lbs. x 60 min. = 500 lbs per hour500 x 1.0 = 500 (1.0 is the specific heat of water)

2005, National Energy Management Institute Committee. All rights reserved.