
Installation, Start-Up, Adjustment and Maintenance Manual
24
1
2
3
4
5
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P
P
Legend:
1
2
3
4
5
6
7
Flexible Connection
Pressure/Temperature Tap
Water Filter/Strainer
Regulation Valve
Water Pump
Fill/Drain Valve
Expansion Vessel
Air Handler
OWC-5
Chiller
Figure
10
–
Piping detail with Air Handler
Size the pump for the system shown in Figure 10
. The supply piping is 75’ long PVC. The air handler
has a 5 ton chilled water coil with a pressure drop of 2.9 psi.
Solution:
First you will need to determine the GPM of the system. The Omni OWC-5 has a flow rate of 12.0
GPM and a pressure drop of 13 feet of head. This is the first piece of information that is needed to
size a pump. With this information, the pipe size can be found from Table 4. You will find that 12 GPM
has a recommend size of 1” Plastic Pipe with a friction loss of 3.77 feet of head per 100’ of pipe.
Now you need to find the pressure drop of the system. To get the total system pressure, you will need
to find the following information:
Feet of head from Feet of head from c Feet of head from coils + Feet of head
from fittings
Let’s do them in order. You already know that there is 75’ of PVC pipe for the supply line. This number
needs
to be doubled to include the return piping as well. You have 150’ of 1” PVC pipe with a friction
loss of 3.77 feet of head per 100’ of pipe. Using Equation 2, you get,
150’ x 3.77 = 5.7 feet of head from piping.
100’
.
We know the pressure drop of the OWC-5 is 13 feet of head. The pressure drop of the air handler coil
is 2.9 psi. You will first need to convert this into feet of head using the relationship 1psi = 2.31 feet of
head. Multiply 2.9 by 2.31 and it equals 6.7 feet of head.
The last pressure drop you will need is that of the fittings. You need to look at the system and get the
total number of fittings by type and size. The sizes and pressure drops are all the same in this
example. A listing of the materials and the corresponding equivalent lengths as shown in Table 4 are
as follows:
5 -
1” Tees with through flow
0.9 feet each
4.5 feet total
3 -
1” Ball Valves
0.3 feet each
0.9 feet total
1 -
1” Strainer
5.0 feet each
5.0 feet total
2
– 1” Flexible Connection
Negligible
0.0 feet total