# How to size chiller capacity?

104 views asked Mar 1, 2015
retagged Mar 1, 2015

Chiller capacity:

C= Q/12000

C= Chiller capacity in Ton
12000= one Ton of refrigeration in Btuh
Q= building block load for cooling at the time of building peak hour (Sensible +Latent) in Btuh

In some instances, the chiller’s capacity is indicated in Kilowatts (kw), (1 ton=3.5kw).

Chilled Water Flow:

F= Q/(500 ∆T)

F= water flow through chiller in gpm
500= conversion facto for lb to gpm for water, 8.34lb/gal X 60 min/hr=500.4
∆T=Temperature difference of chilled water supply and return ℉ (can be 10, 12, 14, 16, 18, 20).

If 50% water and 50% glycol is being used instead of 100% water, the mixture of water and glycol will have a lower density versus using 100% water. Therefore, the flow formula will be:

F= Q/(450 ∆T)

The chilled water flow in chiller varies at different temperature (∆T):

∆T ()

gpm/ton

10

2.4

12

2

14

1.7

16

1.5

18

1.33

20

1.2

Using higher ∆T makes the pipe sizes smaller.