Rule of Thumb for selecting the right chiller cooling capacity according to Fan Coil capacity

[Popcorn64]

Hi all,

I am wondering if there is a rule of thumb to find out the right size of chiller plant according to the total of water fan coil cooling capacity need.

As we know, the chiller plant has to be lower cooling capacity than the real need of the heat load.

I have some rule of thumb such as 2 gpm/ton to 2.5 gpm/ton to find out the flow rate in the water loop and 3 gpm/ton for the seawater condenser.

I am new in the marine industry and I would like to understand how to find it out.

Thank you

 

[pocketengineer]

As far as I know, there is no published or "quoted" rule of thumb to size the chiller plant. For building projects, the engineers/designers will use their experience gained from different type and usage of buildings to apply a "diversity factor" for his design. I won't call 2 gpm/ton - 2.5 gpm/ton as rule of thumb for chilled water flow. It depends on your system delta T design. Conventional 2.4 gpm/ton is based on delta T of 5.5 oC.

 

[willard3]

Rules of thumb will cause you great trouble and are no favor to your client.

Do a good heat gain/loss analysis and that will tell you the cooling load.

 

[Popcorn64]

Thank you guys for reading my post.

pocketengineer I should have been more accurate you are completely right the gpm/ton is according to the delta T. I read an article from ashrae and they called that a rule of thumb but thank you to tell me what you think. I am not a native english speaker.

So, this a bit annoying for me because there is no rulee and I don't have experience in chiller system. Maybe I have to consider how long time the chiller has to tun and the water volume in the water loop.

In same time to reply to willard3, I do a "good" anaysis of each room to cool down (It's for a yacht), so I know the total load required.

I am not use about yacht airconditioning system because I worked before for heating floor and I get used to size the heat pump at the same size of the loss load.

The problem with chiller for this kind of application if I take the same size is going to be oversized and it will start ans stop so often, maybe low pressure problem and then overheat trouble.

To clarify everything, I have been working for no longtime in a firm in Asia but I am really surprised how they worked, they don't really have the skill to do so but they do!

They even don't ask me about it. I work on something else but I would like to understand because the boss is not able to explain me why he does this way. Sounds crazy but to long to explain.

If you are interested I could tell you some crazy thing he says and does about airconditioning system!! By the way, I am not going to stay too much here but air conditioning on marine industry seems interesting.

Thanks all