How do I size the water pump for chiller

The two sizing parameters required for a pump are

1- Water Flow : this is the same as the chiller water flow. So if you have a chiller selection it will show water flow in gpm, use it for the pump

2- Head : which is the friction of the piping, fitting, equipment the pump must overcome. This need to be calculated.


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Originally Posted by serwan

how do I size the water pump for chiller

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You need to determine the largest possible demand for chilled water at any given time and size your pump to accommodate that flow. In doing so you need to make sure that the flow is within the min/max requirements of the chiller.

This really goes back to how the chiller is sized. Are you sizing the chiller for the sum of the maximum demand of all zones, or are you sizing it for the maximum load of the building at any given time?

For example the total building load may be at 4:30 PM on August 17th. However at that time the zones on the east side of the building may be greatly reduced and not at their peak.

If you were to sum your zone loads for the chiller selection you might be adding the peaks of all the zones and thereby oversizing your chiller.

HTH

Hi,

We have an installation of chilled water pump in 3rd basement of building has 160 Mtr. Height.

the pump discharge head is 160 ft.

The question : what is the working pressure for pumps to be design?

is the 160 Mtr. (16 Bar) static head will be apllied on pump while pump in stop position?

Is the suction pressure ( 16 Bar) will be 0 while the pump in operation considering that system is closed type ( fully sealed)

I don't believe that we can have completely sealed system, therefore we are using prissurisation unit and therefore pumps while in operation the suction pressure will be Approx. 16 Bar whereas the discharge pressure will 16+4.2 =20.2 bar.

I hope to recive your comments on the above mentiond.

with my best regards,

Hamdi

tim_45, not sure where you came up with the 160 ft for the discharge of your pump but it should have little to do with the height of the system. You SHOULD have a completely sealed (closed loop) system and therefore your pump need not take into account the vertical height of the building. The pump inlet static pressure will equal the highest point of the chilled water system.

However I think you are on the right path ensuring that you do have some positive (static) pressure at the highest point of the system by adding some boost to the system initial fill pressure. A rule of thumb I use is to take the highest point of the building (in feet of head converted to PSI) and add 4 PSI. Once the system is filled there should be no need to continue to add pressure unless there is a leak of the sealed loop.

I hope this helps.