A water chiller repair visit to rectify the non condensables which were discovered in a refrigerant system. This condition happens when a system is purged through with refrigerant. Carrying out this procedure does not remove the air from the complicated internal pipework. Read on to find out how this condition was diagnosed and then repaired...
Because we sorted out various other problems on the first day of the contract, this customer is really happy with Maximus Chillers. We have a 3 year Maintenance Contract with them too. We know that we are expanding in a recession because we always put the customer first. It is easy to win a contract, but to keep one means that we have to provide a service that is second to none. With a full complement of specialist equipment in each mobile workshop and engineers with years of industry experience- Maximus Chillers completes the picture.
Dalton’s Law of Partial Pressures
That all gasses in a vessel will act as if they are on their own. The air in the system works its way round to the condenser where it sits on top of the liquid refrigerant and won’t condense. This is where the term non condensable comes from. Let’s say the condenser pressure should be 8 bar on a system running with R134a refrigerant. The air, acting as if it is on its own, in this instance, was raising the condenser pressure to 15 bar. This was 1 bar below the high pressure trip out. The higher pressure also causes an increase in electricity consumption.
False Reading of Subcooling
A 30°C false reading of subcooling was recorded due to the air in the refrigerant system.
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Water Chiller Repair Procedure
When one of our engineers arrived on site to resolve the issue, he started by decanting the refrigerant from the system. Because the refrigerant was contaminated, he sent it back to the suppliers for recycling.
No refrigerant leak was suspected, but our engineer carried out a nitrogen pressure test as a matter of course. This was passed, so now on to the next phase of the job…
This part of the job rectifies the previous poor repairs. A vacuum was pulled overnight of 2 Torr. This process removed the non condensables and also dehydrated the system.
Switch it On
Half of the new refrigerant was charged into the system, then the remaining refrigerant was charged into the liquid side of the evaporator during operation. This process was carried out until the superheat and subcooling values came to within standard industry guidelines.
Now that a professional repair had been carried out, the condenser pressure was found to be running at 8 bar. The running amps on the compressor had lowered too.
Energy Monitoring during Water Chiller Repair
The power consumption of the various plant around the building is monitored on the customer’s computer in his facilities office. This is to help identify where electricity is being wasted. He has auditors who assess the efficiency of the building and he has targets to meet. He had already noticed the more efficient running of the chiller subsequent to the repairs. The end user also monitors the energy consumption and worked out the cost saving of the repair over time. The repair would soon pay for itself and then start to save the building money.
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Condenser Cleaning during Water Chiller Repair
The condenser on the other system of the same chiller had recently blocked due to grass pollen. Our engineer brushed it down and chemical cleaned it while on site at no extra cost to the customer.
Pressurisation Unit during Water Chiller Repair
The water system pressure was found to be lower than usual due to a fault that had been reported by the customer. The internal pumps of the pressurisation unit had failed. Therefore, our engineer made a manual top up of the water system to the same pressure as had been recorded on the previous maintenance Tick Sheets. The water system readings were then monitored and were found to be nominal.
The chillers are fed by a pump set comprising of two pumps. The second pump is a redundant system (N+1) Both pumps are fed from inverter drives which lower the electricity consumption of the pumps. There had been an issue reported with the building management system (BMS) so Pump 1 was running in Hand. Our engineer changed the running pump over to Pump 2 which he also left running in Hand. This was to even out the running hours between the two pumps.
At the end of the job, our engineer completed a full report on his phone which was uploaded to Head Office in Droylsden, Manchester. He also filled out a Job Sheet with his findings which was duly signed by the customer.
Any Chiller- Any Problem- Any Part- Any Refrigerant- Anywhere- The MAXIMUS ADVANTAGE™
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