Cooling Tower Questions

[realale]

Hey Guys and Gals

Brad @ real ale brewing here

we are about to fire up a new to us chiller that came with a cooling tower in pretty bad shape. We stripped it down, refurbished the interior, replaced the "fill" material and are in the process of hooking it back up. My question is how do these things really work? I know that's a pretty broad question so let me refine my questions:

What controls the fan motor on the chiller ? Is it when the compressor turns on, or does it stay on all the time

What contols the cooling tower pump?

Is there any secondary confirmation circuits to guarantee that the pump is actually pumping to keep the compressor from overheating? We found a johnson control device in the old piping that seemed like it was something like that

We also found a johnson control device that seems like it was tied into the compressor with a probe , is this the thing that turns the fan/pump on based on the temp of the compressor?

Sorry so many questions, but we have never run a cooling tower and after this experience i think we might never choose to run one again

Any help would be greatly appreciated

brad farbstein
real ale brewing co

[jimvgjr]

Hi Brad,

Cooling Towers can be set up a number of ways, here is how we control them:

The Tower Fan is controlled by temperature of the water in the basin, the Johnson control unit you mention on the tower is probably for this purpose. When the tower water temperature goes up, the fan will come on.

Many times there is also an immersion heater that is thermostatically controlled. This prevents freeze up in the basin during extreme cold periods. One of the Johnson Controls T-Stats might be for this too.

We either interlock the tower pump to come on with the compressor, or will even run this pump all the time (if the chiller is under load a majority of the time).

There could be an interlock with the tower pump that would guarantee pump is energized before allowing the compressor to run (usually done with an auxiliary contact on the pump motor starter), or perhaps a flow switch for this- but it wouldn't be too uncommon that there is no interlock. The compressor does have a discharge pressure control that will shut the compressor off in this situation- but generally this requires a manual reset.

www.evapco.com might have some additional information. Feel free to give me a call if you have any other questions. 800.845.7781 ext 203

Good luck,

Jim
Pro Refrigeration Inc.