Maximus Chillers is renowned in Saudi Arabia and around the world as a chiller repair company because we can do anything. Read on to see the repairs that were carried out for a customer of ours in Riyadh…
Evaporator Chiller Repair Company
This site had issues with the quality of the chilled water which is used to cool the process. Therefore, we had recommended that a plate heat exchanger be fitted to the water system to separate the process water from the water supplied to the chillers. This was because the process water was becoming contaminated with plastic particles from the extrusion of pipes which are manufactured on site. We also recommended to fit cleanable Boll filters with a 200 micron filter size. There are strainers available on the inlet to each chiller, but these only catch the larger particles.
Evaporator Tube Cleaning
This visit was before the above repairs were carried out, so we decided to clean the evaporator tubes. We valved off and drained down each evaporator, in turn, and removed the end plates. We have state of the art chiller tube cleaning equipment which we keep in the stores on site. This equipment is used for our customers around the Middle East. We have another tube cleaner at Head Office for use in the UK, offshore and for The Spanish Office.
Decontamination
We set up our equipment next to each chiller and carried out the decontamination process. A lot of contaminants were removed which were causing thermal insulation…
Thermal Insulation
This is the condition where contaminants prevent heat exchange from occurring between the chilled water and the refrigerant in the evaporator. The system therefore runs inefficiently- it stays on longer and uses more electricity. Eventually, the system deteriorates into a safety shut down.
Chemical Clean and Rinse Out
After the decontamination process, we used a chemical which removed any scaling which had occurred. After this had been carried out, we thoroughly rinsed out all of the evaporators.
0161 237 3727
service@maximuschillers.com
Controls Retrofit by Chiller Repair Company
One of the chillers had controls that were defunct and problematic. We sourced a new controller in the UK along with the associated sensors and transducers.
Compressors
This controller was selected because it is capable of running two systems with a Bitzer screw compressor on each. These compressors operate a slide valve which has 4 stages of loading.
Electronic Expansion Valves
The expansion valves are electronic and stand alone. This was convenient as they did not need to be integrated into the controls of the chiller. They work out the superheat by making a calculation between the pressure and temperature of the refrigerant in the evaporator. This is exactly the way our engineers make the calculation when they use an app on their phone.
Fan Speed Controllers
Another convenience found was that the fan speed controllers fitted were also stand alone- again removing the need to integrate them into the controls. A high pressure transducer is fitted to the condenser which senses the refrigerant pressure. A program in the fan speed controller then speeds up or slows down the fans according to demand. This maintains the correct saturation point, therefore giving the required amount of subcooling.
Rip Out by Chiller Repair Company
It is not in the mindset of a chiller engineer to rip the wiring out of a panel. He spends most of his time, painstakingly repairing complicated electrical faults. However, going at a panel with a pair of snips and some screwdrivers can be quite good fun when he gets into it. Not all of the wiring is ripped out anyway: the three phase wiring can be left in place along with the common neutral.
Wire In
The controller was fitted onto the DIN (Deutsches Institut für Normung) rail and then each of the wires was connected from the controller to the terminal strip. From there, the wires were connected to the contractors, the relays, the transformer and other components in the panel. The external wiring around the chiller was also connected and tested for earth leaks.
Commissioning
A parameter list came with the controller, so our engineer spent a day programming each setting. The following morning, after a cup of coffee, he powered up the chiller, a timer counted down and the first compressor started up. After another timer counted down, the second compressor started up too. Minor adjustments were made during the day, then the chiller went into seamless operation.
0161 237 3727
service@maximuschillers.com
Compressor Swap Out by Chiller Repair Company
One of the compressor motors had burned out which had been identified on a previous visit. The oil had also been analysed and was found to be contaminated. On this visit, our engineer valved off the compressor and removed it from the chiller using specialist lifting equipment. The new compressor having been sent to site prior to the visit. Then, he lifted the new compressor into position. The wiring was connected, the mounting bolts were tightened, the pipework was bolted on and a leak test was carried out.
Oil Changes
A new compressor sump comes with a full charge of fresh oil. However, the oil migrates around the system meaning that contaminated oil will return to the new compressor. For this reason, several oil changes were carried out during the visit until a satisfactory oil test was achieved.
Monitoring
The oil was found to be at the correct level according to standard industry guidelines. The discharge and suction pipe temperatures were recorded during varying load conditions and were found to be nominal. Finally, a vibration monitor was fitted to the compressor to show up any imbalances. This was an important last step as excessive vibrations would reduce the new compressor’s lifespan.
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Chiller Tube Cleaning Service
Screw Chiller Compressor Maintenance
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Read more about a DIN rail on Wikipedia.