Dear RE-Forumers,

Appreciate you advise on the following matter. Where I am the temperatures in winter range from -20 deg C to -40 deg C. I am now trying to optimise the settings for summer/winter operations on our BAC evaporative-condenser, in order not to get too high discharge pressure on our NH3 compressors. We have the condenser outside, with a remote sump (no heating).

There are 2 methods of cooling - using water and air (pump and fan). And also two modes of cooling:
a. summer (water spray first, then fan)
b. winter (fan only)
For summer mode, pressure to turn on fan is 10 bar, while winter mode is 8 bar.

I have currently set the switching from "summer" to winter mode to -28 deg C. I noticed that above -28 deg C, that temperature the evap-cond cannot cope sufficiently to liquify the NH3 gas.

What I'd like to know, learning from your experience:
1. at what lowest temperature can water be used to spray onto the evaporative condenser? Any possibility of condenser or water pipes freezing? Our water pipe diameter is DN80.
2. in extreme winter conditions, -25 deg C, what is the practice of running the evaporative condenser - water spray first, then fan; or fan first, then water if the pressure escalates?

Appreciate any other advice on this subject matter.