Chiller flow question

[Reefugee]

I just purchased a 1/3hp Prime chiller. The chiller has a flow rate of 300 to 600GPH.

Why is it that chiller have a minimum and a maximum flow rate? At first, I thought the minimum flow rate is so that that the water does freezes inside the plumbing. But salt water at 35ppm freezes at -1.8C. Can the chiller get cold enough to freeze the saltwater? Second, why a maximum flow? I understand that if you put a bigger pump than is what is really needed, then you are introducing extra heat . Pipe size could be a limiting factor in the maximum flow.

I am wondering if the minimum and maximum flows are more of a recommendation than an absolute. For example, maybe my Prime 1/3hp chiller can actually take a flow of 50gph and as high as 2000gph - but the ideal flow is between 300 and 600 gph.

Any thoughts?

Minh

 

[mcurl98]

too low a flow and it will take too long for your tank temp to drop-chiller will be on a long time. Also, yes, it can freeze. I have worked on my tank (with the pumps off) and have forgotten to unplug the chiller. It froze up. Luckily, it melted before it burst anything when I turned the pumps back on. Too high of flow makes it so the water going through the chiller doesn't have enough contact time to drop the temp.

 

[gabe3d]

I had the same question and did some experimenting myself with my chiller. Too low is not good and takes a lot longer to cool the tank. If I pass higher flow (more than recommended) my tank cools down much faster than hte mid point of what they recommend. Based on the principle of heat exchange you rather have higher flow then lower flow. In essence you are trying to heat up the cold coil in the chiller so you want to pass as much hot water as possible through it, since the bigger the delta in temp the more the temperature will change.

 

[rickh]

It depends on the type and size of the tubing of the heat exchange. You don't want to try to push 2000GPH through 3/4 fittings/tubing on the chiller. R

 

[gabe3d]

I believe that most inline chillers in principle works the same, but you are right about passing too much flow through a small tubing. With more water through a pipe the higher the pressure and i'm not sure if some chiller will be tolerant of the pressure, but i don't see why it would hinder the heat exchange process in concept.

 

[Reefugee]

I understand that there is a limit due to tubing - but higher flow shouldn't really matter as long as the tubing can take it.


Matt - I didn't realize that those chiller get cold enough to freeze salt water.

 

[Chymos45]

I don't think it's the water that one should worry about freezing, but rather the cooling media (think freon or something similar). If the warm water is flowing too slow through the exchanger, then the cooling media would freeze because it is not being warmed faster than the chiller is cooling it.
The max flow is simply an efficiency thing. If the warm water is flying past/through the exchanger too fast, it's temperature is not effectively pulled down. It's not going to hurt anything but your wallet because the chiller will just have to run longer/more frequently.