Our service technicians make up a large part of our work force at Smart Family of Cooling Products. Each service tech (tech = short for technician) runs across a myriad of new installations, unit repairs, and standard P&M (parts and maintenance) work. They travel all over the country helping keep our equipment (and, in some cases, even our competitor’s equipment) running at peak performance. With all the plants they visit, we thought it might be interesting to hear about some of the experiences that one of our techs has run across over his years in the field.
Let us introduce you to one of our refrigeration and air conditioning service technicians. His name is James. He has been working with prestigious accounts like British Petroleum, Marathon, INEOS, Union Carbide, Dow Chemical, and BASF. James is going on 15 years experience in the industry. We formulated a list of questions and we have included James’ responses.
1. What is the most puzzling job you have encountered during your field work?
James: The most puzzling job I’ve seen had to be at a Dow facility. It was at the chlorine block where we have two 300 ton chillers that condition a large switch-gear room. We kept having intermittent “Freeze” alarms. We looked at the run history to see if we noticed anything odd. It seemed the temperature would fall drastically right before the alarm. So we test the pump start/stop with operations and found no problems. Then we restarted and it would run fine for days or even weeks. After several occurrences, we discovered the issue to be a loose wire on the start/stop pump relay for pump #3 in the Siemens control cabinet that was located inside the switch-gear room. It wasn’t even on our skid. Sometimes you feel like you’re chasing a ghost.
2. What was the oddest service job you’ve run across?
James: In my 14+ years of work in the HVAC world, I have seen some strange things. Here is a picture of one such job (bottom right). This is the header after the TXV used to distribute the refrigerant to the evaporator coil. Talk about a Medusa header!
3. On a standard PPM (Predictive Preventative Maintenance) inspection, what items do you typically focus on?
James: With our standard PPM inspections, I focus on the following items:
- First, I run the machine and complete a performance log. I wanted to mention that I have worked for other companies, and in my opinion, the CRR performance log is one of the most detailed log sheets in the industry. This provides us with an excellent overview of how your equipment is running. If it is not at optimal performance, we are going to fix it. That is, after all, what we are there to do.
- Moving on to the preventative maintenance, we rinse the condenser coil and check overall condition of condenser fins.
- Check all the condenser fans for bearing noise or vibration.
- Check all electrical components in control cabinet for any failures (Failed relays on boards, carbon build-up on contactors, burnt or darkened terminals, etc…)
- Leak check the entire chiller with electronic leak detector and also visually inspect for oil seepage.
- Calibrate all pressure transducers and temperature transmitters with accurate gauges and calibrated thermometer.
- Run compressors to 100%. Check the slipper seal and log temperatures and pressures to check superheat, subcooling, and discharge superheat.
- On all water cooled chillers, we also check our condenser and evaporator approach on our exchangers to see if they are fouled.
- Clean up the job site and relay all written findings to the customer via our inspection log sheet. Provide our customer with all the documentation including a deficiency form stating any items that could lead to downtime or LOPC (Loss of Primary Containment).
4. What is the recommended time limit between inspections?
James: It really would be a case by case basis but I would recommend a minimum of quarterly inspections for all chillers, water cooled and air cooled. This keeps your chiller running like it was designed to operate. It also catches an failures before they get worse. Things like leaks, dirty coils, fouled exchangers can be prevented. As units increase in age, we strongly recommend moving to monthly inspections. It becomes much more difficult to keep older equipment running at optimum performance. Having the regular monthly inspections & adjustments can help to achieve that.
Thanks for your time today James and thanks to our readers. We know that all of our readers and our Service Technicians have busy schedules. We only hope that this information is both insightful and helps you, the customer, figure out what necessary steps are needed to keep your refrigeration equipment running in tip top shape. Thank you again for reading.