Process chillers are the most important (and most costly) item in any plant. In an ideal world, a chiller would hold up forever, but the reality is that bad tubes, leaky refrigerant, and many other factors can quickly cost your company money. Operating chillers at their peak performance saves energy and maintenance costs.
Thanks to new developments in centrifugal chillers with magnetic bearing chillers, and new remote monitoring technologies, chiller maintenance has significantly advanced over the past few years. The chiller industry has been moving toward demand maintenance programs and away from pre-determined scheduled maintenance.
Here are 10 of the best maintenance tips to help maintain high efficiency of your chiller.
1. Keep a Daily Log
The daily log should always be the first step in maintaining an efficiently run chiller. Having a daily log will allow you to have a documented history of operating conditions including temperatures, pressures, fluid levels, and flow rates. With the help of remote monitoring technologies, you can inspect machines daily rather than every month. A daily log also allows you to generate daily reports that can catch any maintenance needs before they become a big issue.
2. Keep Tubes Clean for Efficient Heat Transfer
Heat transfer efficiency is very important when it comes to chiller performance. Clean heat transfer is a must to maintaining high chiller efficiency. Minerals, scale, mud, algae and other elements can increase resistance and reduce overall performance. Higher approach temperatures are prime indicators that heat transfer efficiency is decreasing. Condenser tubes should be cleaned annually, or per your maintenance schedule to keep them free of contaminating elements.
3. Treat Condenser Water
All condenser water loops that use open cooling sources require water treatment of some sort to eliminate scale and corrosion. These factors can decrease tube and piping effectiveness. It is a good idea to inspect chilled water loops at least once a year or with remote monitoring.
4. Lower Water Temperature
Lowering the temperature of water entering the condenser will improve your chiller’s efficiency. In some process chillers, the operator will automatically lower the water to overcome issues such as dirty coils. Unfortunately, this will only cure the symptom and not the entire problem. This will also make the chiller work harder for the same cooling effect.
5. Keep Water Flow Rate 3 to 12 Ft Per Second
Changing the chilled water flow rate will affect a chiller’s performance. Too low a flow rate can lower the chiller’s efficiency and possibly cause to laminar flow. The minimum flow rate should typically around 3 ft. per second (FPS). Too high of a flow rate can lead to tube erosion. A chiller’s flow rate should typically be around 12 FPS.
6. Maintain Refrigerant Charge
The amount of cooling a chiller provides will depend on how much refrigerant it moves through the compressor. It is very important to maintain the proper level of refrigerant for the conditions desired. Refrigerant leaks will decrease efficiency and the reliability of the system. A low refrigerant charge will cause the compressor to work harder for less cooling power.
7. Prevent Problems Caused by Air and Moisture
Air and moisture usually will leak into low pressure chillers because their evaporators operate in a vacuum. This can lower the efficiency of the chiller by as much as 4% at 60% load and 7% at 100% load. Purge units will help minimize this from happening.
8. Analyze Compressor Oil
It’s a good idea to collect a sample of the oil from your chiller about once a year and send off to a laboratory for chemical analysis. The oil should only be replaced if needed. High moisture indicates a problem with the purge unit. Low pressure chillers should have their oil analyzed more frequently. It’s also very important to check the oil filters for pressure drop and replace them if needed.
9. Check Starters and Motors
To keep starters and motors working efficiently, check the safety and sensor calibrations on the microprocessor controls. Electrical connections, wiring, and switchgear related to the chiller need to be checked for hot spots and worn contacts. To prevent insulation issues, you can test the electrical motor windings for resistance to ground.
10. Install Variable Speed Drives
A chiller motor is typically the largest single electrical load in a building. With the right operating conditions, variable speed drives can offer significant energy savings. Varying motor speed matches motor efficiency to load and wastes less energy. Variable speed drives also act as a soft starter to lower the current for the motor to almost that of the full load running amps. This is an important factor for chillers operating on emergency power generators.
All of these factors will help increase the life and reliability of your chiller, saving your company time and money. For more information on chiller maintenance or information about chiller rentals, visit our website at chillerservicenw.com.