Curling Rink Problem

Hi, I'm new to your forum. I'm a retired mechanical engineer with limited refrigeration knowledge. I belong to the Guelph Curling club in Guelph, Ontario, Canada. This morning at our club we encountered a problem with our artificail ice surface which we have never seen before. Let me give you a brief overview of the building and the system to help you understand the problem.
The ice surface is approximately 150 feet by 110 feet. The ice is cooled by brine which flows through pipes layed on a sand floor. The feed and return headers for these pipes are on the 150 foot side next to the compressor room.
One of the requirements of the system is to keep all of the ice surface at the same temperature. This morning when our "ice maker" reported for work he discovered that the ice at either end of the 150 foot length (appoximately 35 feet at each end) was significantly warmer than the ice in the middle of the rink. The ice that is warmer is very slick to walk on, almost to the point where it is not possible to curl (the sport that is played on the ice surface)
The refrigeration system appears to be working normally and the brine system also appears to be operating normally.
Any thoughts? Thanks in advance for your help and tolerance of my limited knowledge.

I haven't worked on Ice Rinks before but my first thoughts are towards the brine circulation pump.

It sounds as though the circulation at the extremeties is suffering leading to a reduced refrigeration effect in these areas, possibly caused by a reduced mass flow rate.

I work in an ice rink as a maintenance tech with also limited refrigertion knowledge and I would agree with Frank about brine circulation. Check the pressure at the circulation pumps and see if the pressure has dropped or increased. A decrease would normally indicate loss of brine (possibly a leak) whereas an increase would normally indicate a possible blockage in the brine piping system. Hopefully you have daily log sheets to refer to previous readings and also pressure gauges connected at the pump or at the chiller barrel. I would also check the leaving and entering brine temperature at the chiller and see if those numbers have changed or have a large seperation. Normally there should be a 3-5 degree "F" seperation and check to see if the chiller is meeting its chilled water setpoint. Also check the site glass on the expansion tank for the brine and see if it has dropped since it was last checked which would indicate a possible leak. Check the pump itself. If you have a backup pump in a switching system (providing it is the same pump as the one currently running) switch to it and see if the pressure gauge increases at the pump or at the chiller barrel whick would indicate a faulty pump Hope this was helpful.