level controls for towers

JackEnnisMartin

Thank you for the help.The condensers were always connected to city water prior to 2002 and they used a standard water regulating valve ,water in and water to drain. Costly to be sure: but, they worked exremely well. I have not seen in my travels the three port style it is very interesting! The refrigerant pressure to the expansion valves was always in the correct range as these condensers were modulated to maintain optimium curves. I have gone to the BAC website for imformation and the design for this tower is not at all correct when taken in context to their recommendations. I am not trying to "bash" anyone in the engineering field; but, towers and refrigeratin engineering is not taught as a subject in our engineering courses at University. I can see, after the information BAC provides ,how easily you can get into a great amount of trouble using the standard practices for pump sizing etc. I wlll do my best to have some numbers from the condensing units later in the week.
Jack Ennis Martin

JackEnnisMartin

level controls for towers

Hello
We have been using something new for us on cooling towers and evaporative condensers ;rather than the traditional float controls. We have had some trouble with specific jobs retaining the proper levels in the sumps. We happened on a boiler control ,which is proving to be excellent It is a Macdonnell 802 boiler level control. It uses a probe and an electonic interface. The control is avialable in 110 or 24 volts models and we have selected the low voltage model. The company is also selling a model for remote sensing now as well. We use it to control a 3/4 inch ball valve ,with a Honeywell Belimo style acuator. We find this acutator does not cause any water hammer as it is slow close and open. The control holds the water level to a half inch in our experince. It has solved two problems we have had on a BAC tower and an ancient Carrier evap. condenser. I also have a question :I am trying to find out if packaged Trane water cooled condensing units as a rule, were sized for tower or city water . The year of buld is 1959 and 1960 ,the physical size of the condensers to me, indicate city water. I had all the imformation off the units:but,I cannot find it at the moment. My contention is ,if a the time of purchase, the engineers would have indicated in the spec. if the units would be on city water? I have tried Trane and they are no help at all.
Thanks for the help
Jack Ennis Martin

Brad White_84

On a related method, Jack

I recently adopted this practice, similar in concept to yours: I use a conductivity type probe level sensor. Instead of having the fill valve outside with all the attendent heat tracing, insulation and such, the valve is indoors. In fact it is in the mechanical room near the pumps and bleed off valve. The fill and blow-down can easily be interlocked, metered, monitored. I do not have to haul a 2.5" copper pipe up to the roof (at today's prices??) and no freeze issues. Life is good.

To your question: SOME but not all of those units that I have used had different condensers depending on the entering water. The city water one's had charts for EWT in the 40-60 degree range and condenser water units were selected for the 75-90 degree range, sometimes with extended range.

I take it that the condensers are a tad on the small side compared to 85-degree water users in that tonnage range? I can see you answering the question initially the same way I would.

The one's that had no distinction that I could tell probably could work with either. Both were cupro-nickel or red brass for durability and rated for 150 PSI. If you have a nameplate that might tell you something. I can imagine when an 80-degree water user was hooked up to city water, the refrigeration side probably compensated with a 3-way valve or other capacity/head pressure control feature.

Not much to go on, sorry. I do have an old Trane design manual in the office, I may crack it open Monday.

Brad

Techman

Water condensors

Evening! Is it true ,that tower condensors have 3 water connections and city condensors have 2 connections ?

Brad White_84

You know, Techman-

I think you are right at least on some models or at least on to something. I am thinking back to an older (1950-60's) Trane or Carrier water-cooled unit in an office building. Probably 12-15 tons? Maybe as much as 20 tons?

Early in my career (late 1970's) we were trying to figure that out. What we came up with is that there was an in-port, recirculating port and a drain port. The unit would take in city water, recirculate it via a pump internal to the unit and external to the condenser until it's temperature benefit was gone then bleed off the difference to maintain temperature. I imagine it was a 3-way valve.

I suspect that the goal was more steady refrigeration control, not water conservation at the time. But it beats straight-through flow to drain without modulation.

Knowing this was not essential to our work, just satisfying our curiosity much as we all seem to be doing everyday.