Trane chilled water reset question

[buckfever]

I have 2 600 ton CVHE machines, no drives. I am looking to do chilled water reset based on return water. I was wondering if someone could explain to me in simple terms what Return reset ratio means, Return start reset means and Return max reset means when my set-point is at 43.

Thanks in advance!!!

[GT Jets]

I have 2 600 ton CVHE machines, no drives. I am looking to do chilled water reset based on return water. I was wondering if someone could explain to me in simple terms what Return reset ratio means, Return start reset means and Return max reset means when my set-point is at 43.

Thanks in advance!!!


This is going to be quick, but might help you out..

First of all, max reset is just that, think about how high you want to allow the leaving temp to go....Just that simple.

Reset ratio is just that also, think about how much you would like to reset the leaving water temp with a decrease in return water temp...

Return reset start, well, think about how low you want the return water temp to be before it starts the reset process..

A good starting point with a leaving temp of 43*F..(if you have a 10*F machine);

Return reset start would be in the range of 50*F (or 7*F delta)
Return reset ratio would be 1:1 (1*F per degree dropped in the return).

Max reset would be say, 5*F..

Gotta go for now, but good luck...

BTW return reset works well for energy savings providing your building can get away with warmer supply water temps when the load is low..However, you have to be careful if the system is variable flow, higher temps mean more flow, it will chase it's tail for eternity...

Does not work for process stuff too well.

GT