Category Archives: Overseas Customers

Two engineers in Marbella stood next to a chiller under repair in a plant room

Marbella Chiller Repair

Our overseas engineer carried out technical support for a Marbella chiller repair recently. The trip was arranged for him to carry out training for our engineer from The Spanish Office. The site was an exclusive gated community with a fitness suite and a social club…

Marbella Chiller Repair- Plunge Pool

Part of this facility comprises a sauna and a cold water plunge pool. This plunge pool is kept at 8°C with the use of a chiller. The chiller was found to be in fault by the onsite maintenance engineer, so he arranged a Call Out…

Sensor Failure during Marbella Chiller Repair

The fault message was reported to be E1 which suggests the failure of the Water In sensor. The chiller, in the picture, is bespoke with the chilled water pump being located behind the chiller.

Dusty Connection

Pedro, our Spanish engineer is looking pleased with himself in the picture because he noticed a dusty connection. He used our in house chemical, formulated in our laboratory at Head Office, to clear out the dust. This is because our chemical can be used with electrical wiring and terminals. Our overseas engineer is pointing at him in approval as he is pleased that he notices things like this.

Misdiagnosis

A lower skilled engineer would just have changed the sensor. This may have therefore required another visit to site because of the same issue. Customers do not like extra visits and neither do we as we can’t charge for a mis diagnosed fault. We have a high customer retention rate at Maximus Chillers because we have very diligent and thorough engineers. This is just part of what we call the MAXIMUS ADVANTAGE™ Any Chiller- Any Problem- Any Part- Any Refrigerant- Anywhere.

Tighten Wiring during Marbella Chiller Repair

As a matter of course, all of the wiring on the chiller and the compressor terminals were tightened. Some terminals could be tightened a little, but none of them were found to be loose.

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NTC Sensor

The sensors on this chiller are the NTC (Negative Temperature Coefficient) type. That is to say that when the sensors are warmed, the resistance drops. The resistance at the plant room temperature of 25°C was referenced against our chart for that particular sensor. The reading checked out okay, but it could have been that the sensor had an intermittent fault…

Possible Intermittent Fault

An example of this would be a broken wire in the sensor that intermittently disconnects. Should this happen, the sensor would read off the scale and so generate the E1 fault. Therefore, the sensor was changed using our car stock…

Mobile Workshop for Marbella Chiller Repair

This car stock of a range of commonly used parts and materials can often remove the need for a return visit. This saves you- the customer money!

Test Operation

The new sensor resistance checked out against our chart. Also, the temperature reading on the screen of the controller checked out against our calibrated digital thermometer. With the chiller running, the chilled water started coming down to temperature and so it was time to move onto the next phase of the visit…

Chiller repair at a top market residential complex with white buildings on a hillside in Marbella
Bottom right building is the five floor fitness suite

Site Survey during Marbella Chiller Repair

The rest of the plant is located behind the curved wall at the top of the building in the photo. This plant comprises of…

Swimming Pool Heat Pump

This is a chiller with an air-cooling evaporator and a water cooled condenser. The condenser is the part of the plant being used to heat the pool. The heat energy absorbed from the ambient air and the heat energy added to the refrigerant system from the compressor, warms the water passing through the condenser from the pool. This is a very efficient use of electricity and is becoming more and more popular due to environmental concerns.

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DX Units

All 5 floors of the building are heated and cooled by 2 large DX units which are also located on the roof. The onsite engineer cleans the filters of the fan coil units at periodic intervals and also checks for faults.

Run Testing

These units can be run tested at 100% for 15 minutes to see if there is a refrigerant shortage, or if any of the valves are stuck. This is done by programming the main PCB with push button service settings. The correct setting can be selected by pressing the button, in service mode, a pre determined amount of times.

Check Valves

There are check valves in the DX units which are used for the reverse cycling of the machine. These can become stuck which causes a malfunction to occur.

Reversing Valve

This valve is also known as a 4-way valve and reverses the flow of refrigerant, changing the mode from heating to cooling. This valve can also stick, again causing a malfunction to occur. When this fault occurs, the refrigerant partly goes in the desired direction and also back feeds in the wrong direction. This causes the complete malfunction of the plant. The repair requires the valving off of the system and the swap out of the valve.

EEVs

Each fan coil has an expansion valve which can shut down completely. This removes the need for a separate solenoid valve to stop the refrigerant passing through during an off cycle.

Heat Mode

In this mode, the expansion valve is wide open and so does not restrict the flow of the refrigerant. This is because the heat exchanger in the fan coil is condensing a high pressure, hot, discharge gas into a subcooled liquid.

Cool Mode

In this mode, the expansion valve uses a sensor on the inlet and a sensor on the outlet of the evaporator to regulate the superheat. A low pressure, cold, liquid/ vapour mix is being boiled off in the evaporator and so absorbing the latent heat from the building.

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Read more about Calorex swimming pool heat pumps on Dantherm.


Technician in Saudi working on a chiller evaporator during the repair

Saudi Chiller Evaporator Repair

On a recent visit to Saudi, our overseas chiller engineer carried out an evaporator repair. This customer flew us out because of on going issues with their evaporators. Various recommendations were made to improve reliability….

Water Treatment

A full analysis of the chilled water quality was carried out including samples being sent to our laboratory at Head Office.

Bacterial Growth

There had been a bacteria problem which had occurred 4 years ago. The water temperature and conditions can be just right for a particular type of bacteria to thrive. The bacterial growth spreads around the water system, the plate heat exchangers and the evaporators until it completely coats all surfaces.

Thermal Insulation

This bacterial layer can be 2mm thick and acts as insulation between the heat exchanging water and refrigerant. This dramatically reduces the capacity of the chillers. The chillers achieve set point due to not sensing heat. The factory gets warmer due to not being able to reject heat.

Saudi Chiller Evaporator Repair using Biocide

The customer had brought in a chemical treatment company who started using a biocide to control the bacteria. This had worked effectively, but it had a knock on effect…

Corrosion

The evaporator tubes had been corroded away with the over use of the biocide. When our overseas engineer inspected the MSDS (Material Safety Data Sheet) for this particular chemical, he found it to be corrosive. When he analysed the dosing rate, he found that it had been significantly over dosed. This over dosing had corroded and rotted through the copper evaporator tubes which was causing re occurring refrigerant to water leaks.

Solution

The solution was to recommend a full drain down of the water system when the factory was in shut down. A list was provided to the customer detailing which chemicals should be used and their dosage. This list included a biocide, an inhibitor, PH control chemicals and chloride control chemicals.

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Water System Components

The water system components were found to be installed in the wrong position, or not installed at all. This was found to be another major contributing factor to the frequent evaporator failures. A previous design company had sent our customer the plans of how to build the water system, but these plans had been mis interpreted by the local industrial pipework company.

Incorrect Flow Rate

The onsite chiller engineer has all of the necessary charts and tables along with the design specifications supplied by the evaporator manufacturer. However, because of the above, he had found it impossible to regulate the correct flow rate through the evaporators. This incorrect flow rate had caused various evaporators to weaken and then burst.

Strainer

Most of the evaporators were found to be in use without a strainer fitted. This meant that foreign objects from around the water system were rattling through the evaporators and then causing damage.

Re Installation

After a report was forwarded to the onsite repair manager, a local consultant was brought in to oversee the re installation of the chiller pipework. Each chiller’s water system pipework was scheduled to be repaired one at a time, this was so that minimal disruption was caused to the factory process.

Test Points for Saudi Chiller Evaporator Repair

Pressure and temperature gauges were fitted at the same time that the chiller pipework was re installed. This was to allow the onsite chiller engineer to carry out the necessary adjustments to the water system flow rates.

Rebuild during Saudi Chiller Evaporator Repair

The photo shows one of the chiller evaporators with the end plate removed during repairs. The onsite chiller technician in the photo was carrying out an inspection to the tubes to identify which ones were leaking.

Tube Repairs

The leaking tubes were then taken out of use. Standard industry guidelines were used to pressure test the rest of the evaporator to ensure the integrity of the system.

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Dehydration Process during Saudi Chiller Evaporator Repair

Next, the water that had got into the refrigerant system needed to be removed. This was a difficult process as the compressor had sucked the water through and discharged it into the condenser. Luckily, the amount of water going through the compressor had not damaged it. This was because the compressor is a high quality Bitzer which is very robust. The vacuum pump was fitted to the system and the moisture removal process was carried out over a period of weeks.

Refrigerant Recharge

Having successfully carried out the dehydration process, the refrigerant system was charged with R407c refrigerant. The refrigerant quantity on the data plate was used a guideline. However, system sanding pressure was achieved as the pressure equalised between the refrigerant cylinder and the refrigerant system.

Low Pressure Trips during Saudi Chiller Evaporator Repair

The chiller was started up and then tripped on low pressure shortly afterwards. This was because there was still a shortage of refrigerant in the system. Therefore, more liquid refrigerant was charged into the system until the chiller ran without tripping out.

Superheat and Subcooling

The superheat and subcooling values were found to be outside standard industry guidelines. Therefore, refrigerant was continued to be charged into the system under full load conditions. The onsite chiller technician continually monitored the readings on his test equipment and the program readings of the chiller. After an hour of trimming the refrigerant charge and monitoring the readings, he got the superheat and subcooling values to be within standard industry guidelines.

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Read more about why a chilled water system needs treatment on Kimpton Energy Solutions.


Engineer wearing Saudi headgear during chiller repair

Saudi Chiller Repair

A Saudi chiller repair has just been carried out by our overseas engineer Dave Thompson. There are 17 air cooled industrial process chillers across 5 factories in Jeddah, each with a capacity of 900 kW. This visit was mainly concerned with a controls issue…

Saudi Chiller Repair of SCADA Controls

In each factory, a Supervisory Control And Data Acquisition system controls plastic extrusion moulding and plastic injection moulding processes. Each SCADA system gathers real time information about the chillers, the pumps, water temperatures and flow rates. The system allows each process manager to monitor, adjust and control their process from the Supervisor…

Supervisor

This is a central control computer in the production office in each of the factories. It comprises of a PC with a hard drive and a HMI (Human Machine Interface) which is a computer monitor on each desk. This screen has graphic displays for each part of the plant: the chillers, the chiller pumps, the process pumps, the PHE pumps (Plate Heat Exchanger) and a 3 way valve on each PHE which is controlled by a Proportional Integral Derivative calculation.

Control

Each SCADA system allows the process managers to simultaneously change set points, sequence, control and adjust the above while their process is running. If an alarm occurs- an alert shows on the HMI. This allows a process worker to correct the issue without an interruption to the process.

And Data Acquisition

The data acquisition is from: chiller feedback, pump feedback, pressure transducers, temperature sensors, flow meters and the 3 way valve positions around each factory. This data feeds in to RTUs (Remote Terminal Units) which then feed back to each Supervisor.

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Plate Heat Exchangers

A PHE is used in each factory to keep the process water separate from the chilled water. The load varies depending on how many lines are running, so each 3 way valve opens to the required percentage according to demand.

Saudi Chiller Repair of Oscillating 3 Way Valve

On this visit, however, our overseas engineer noticed an issue in one of the factories: the 3 way valve was oscillating from the closed position to the open position. This was causing a short cycling condition to occur on the chillers. Also, each time one of the two chillers went off, a 5 minute timer counted down to protect the compressors. Therefore, the process water temperature was found to be too high at 18°C, the setpoint being 16°C.

Luggage for a Saudi chiller repair outside a hotel in Jeddah
Overseas engineer arriving at the hotel with tool case for the repair

Saudi Chiller Repair of Proportional Integral Derivative Program

Our overseas engineer knew immediately what was causing the 3 way valve to oscillate: the PID values needed to be tuned. A PID is a simple mathematical program that makes three different calculations to determine the required position of the 3 way valve. These calculations are made simultaneously and balance out over time. The way our engineer tuned the PID was to set all three values to 0 and then adjust them, one at a time, starting with the Proportional…

Proportional

This value could be seen as an accelerator. The larger the value, the quicker the 3 way valve opens when a sudden increase in temperature is detected. This occurs when a new line has just gone into production. Our engineer followed the procedure which was to increase the value until oscillation occurred and then half it. In this instance the value he arrived at was 10 (this is a multiple of the calculation, not a percentage) This completed, he then moved on to the Integral…

Integral

The integral calculation could be seen as being an average over time. Again, the number given to the calculation is a multiple. The larger the number- the more powerful the influence that this calculation has over the 3 way valve. After some trial and error, our engineer tuned this calculation to a value of 2. He then moved on to the Derivative…

Derivative

The derivative calculation could be seen as being a break. It prevents the PID from keeping the 3 way valve open too long and overshooting the set point. Care has to be taken with this calculation, as it fights the other two. Indeed, this calculation can be left at 0 and the valve will still work. After some time and some careful adjustments, our engineer tuned this calculation to a value of 1.

Further Tuning

The PID was tested by our engineer repeatedly by changing the set point and seeing how the 3 way valve reacted. He monitored: a sudden change in demand (Proportional), how the valve settled down over time (Integral) and how the valve closed as the set point was achieved (Derivative) By trial and error, he further tuned the Proportional to a value of 2.

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Improved Performance during Saudi Chiller Repair

Because of the above tuning, the 3 way valve started sending a steady heat load up to the chillers. This caused the chillers to stop short cycling. The issue of the high process water temperature had improved to 17°C but the setpoint of 16°C was still not being achieved.

Saudi Chiller Repair of Chillers Unloading

Therefore, our overseas engineer went down to the plate heat exchanger and just stood there staring at it for a while. Customers comment about chiller engineers who just stand there staring at something! He realised that when the 3 way valve was partly open, the heat load was being starved up to the chillers which was causing them to unload.

Setpoint Adjustment

The solution was to adjust the set point of the PID to 10°C and the chiller setpoint to 12°C. These set points caused the 3 way valve to open fully and all the heat load to be sent up to the chillers. 14°C water started coming out of the other side of the PHE. This water then mixed in the weir tank and gave the process the desired water temperature of 16°C. At low load, the 3 way valve partly closed and then shut down altogether when production stopped.

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Chiller repair company for a row of grey air cooled chillers in Saudi

Chiller Repair Company

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.

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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.

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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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Read more about a DIN rail on Wikipedia.


The rock of Gibraltar at night where chiller maintenance is being carried out

Gibraltar Chiller Maintenance

With The Spanish Office now open down the road, it has never been easier to carry out Gibraltar chiller maintenance. In this article, we will be focusing on a visit by our overseas engineer from Head Office in the UK. He visited Gibraltar to carry out training to our engineer from The Spanish Office near Malaga.

Gibraltar Chiller Maintenance Contracts

We have a three year maintenance contract for the chillers at a facility on The Rock. This was the issue that was rectified while our engineers were on site…

Water System

Our engineer from The Spanish Office had noticed that the refrigerant system readings had deteriorated in between maintenance visits. Our overseas engineer confirmed that the this was correct. The performance of the machine had gone down and it was struggling to achieve set point. The same amount of load was available from the building.

Remote Plant Room

A remote plant room is located inside the building on the third floor. It is where the BMS (building management system) panel is located which starts the pumps and other plant.

Supervisor

The BMS panel is also linked to the supervisor (a computer) in the facilities manager’s office on the first floor of the building. The supervisor is where the timers are adjusted to bring the chillers and other plant on and off according to a schedule. A low ambient thermostat is also available to hold the chillers off on cold days in the winter.

Pump Data Plate

Whilst in the plant room, our overseas engineer noticed that Pump 1, which was feeding the chiller at the time, had recently been changed. This pump was one of two pumps in a pump set. On interrogating the data plate, then reading the manual for that pump, our engineer noticed that the specifications were wrong for this particular chilled water system. Therefore, he decided to set the toggle switch on the BMS panel to pump 2 which was the redundant pump.

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Improved Readings during Gibraltar Chiller Maintenance

By the time our engineers returned to the chiller compound at the back of the building, the chiller had begun to load up. It had previously been limiting its loading to prevent a trip out. Now the water system readings had improved to optimum values, the chiller got on top of the load. It then unloaded to match the load coming from the building.

Old Pump Leaking

The customer informed our engineers that their onsite maintenance engineer had recently changed the pump with one from their stores. The one in their stores had the same mounting plate dimensions so it was a quick fix without the need to buy a new one. The old pump had been found to be leaking water from the shaft seal connecting the pump to the electric motor.

The MAXIMUS ADVANTAGE™ Any Chiller- Any Problem- Any Part- Any Refrigerant- Anywhere

Obsolete Parts

As we work on all chillers, we have to be able to do anything. This is because parts are sometimes obsolete or unavailable. Therefore, we have the technical ability to retrofit new parts to old chillers. This dramatically saves in the carbon footprint of buying new plant.

Extending Lifespan in Gibraltar with Chiller Maintenance

We can extend the life of your chillers by at least 10 years with our thorough maintenance procedures. Some problems can be rectified whilst we are on site at no extra cost. This is because each vehicle in our fleet is a mobile workshop with a treasure trove of commonly used materials. Repairs can also be carried out at the end of the visit as we carry an extensive range of parts too.

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Controller Swap Out

When a controller malfunctions and is found to be obsolete, it can constitute a big problem. However, it is no trouble at all for Maximus Chillers as we have Carel controllers on the shelf.

Strip the Panel

First, we strip the wiring, the electrical components and the old controller from the panel. We keep the 3 phase wiring, the common neutral and the transformers. This is because we reuse them for the new controls.

Fit New Components

Next, we fit the new controller, the condenser fan switches, the sensors and the transducers. Electronic expansion valves and compressor variable speed drives can also be fitted at this stage if required.

Wire Up

Each wire between the controller and the various components in the panel is wired up one at a time. The external components around the chiller are also wired back to the panel.

Commissioning

The final part of the job is the commissioning phase where the program settings and the fan switches are adjusted. This process gets the machine to settle down into seamless operation. A day or two is usually taken to do this, with a courtesy visit arranged a week later to iron out any teething problems.

Supply Chain for Gibraltar Chiller Maintenance

Where a compressor needs rebuilding, it can be lift and shifted to be rebuilt at our compressor remanufacturing facility at Head Office in the UK. We can also carry out strip down and rebuilds on site using our engineers from The Spanish Office. We have suppliers in Malaga for consumables and refrigerant. We also have a weekly shuttle service from the UK to replenish the Spanish Office. This is because we have excellent suppliers in the UK who provide second to none technical support in the selection of parts. UK equipment is also of exceptional quality, so things like vacuum pumps and refrigerant gauges are replenished from the UK too.

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Read more about Gibraltar on Wikipedia.


Dirty tubes on the left and clean tubes on the right after chiller condenser tube cleaning

Chiller Condenser Tube Cleaning

A nice job for our overseas engineer: to carry out chiller condenser tube cleaning in Cadiz, Spain. We have The Spanish Office near Malaga with a manager and an engineer out in the field- so our Spanish engineer assisted our overseas engineer.

Centrifugal Chiller Condenser Tube Cleaning

The factory has 4x water cooled centrifugal chillers with a combined cooling capacity of 8 MW. The chillers cool down a process involved with the production of an industrial chemical.

High Condenser Pressure

When we looked through our Tick Sheets we could see a gradual deterioration of the high side readings over a period of time. This showed us that an overhaul needed to be carried out on the condensers.

Water Tower Contaminants

We think that the fouling was due to contaminants that were carried in the air from around the factory. Each condenser has a water tower which is open to atmosphere. The condenser cooling water enters the cooling tower at the top. It runs down along plastic slats which are stacked on top of each other. In the opposite direction, air is blown up using large blowers. The air flow cools down the water, which then returns to the condenser. This process is how the contaminants from the air end up in the water.

N+1 Redundancy

This is an algebraic way of saying that there is twice as much cooling as is needed. Where N is an amount of something and +1 means another one. Redundancy is needed when a process is critical. In this instance, the factory would grind to a halt if the chillers went down. Therefore, only two of the 4 chillers run at any one time.

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Sequencer

A sequencer is available to switch between the chillers when they go into fault and to balance the compressor run hours. We decided to start work on Chiller 1 as this was a system in standby. The next chiller in standby was Chiller 2. After this chiller had been overhauled, we switched Chiller 3 off which brought Chiller 1 on. Then, when we isolated Chiller 4, the sequencer brought Chiller 3 on. Before leaving site, we temporarily lowered the setpoint for all 4 chillers to watch the sequencer bring all of the chillers on together. We then put the set point back to its usual setting, whereby Chillers 1 and 2 remained running.

Shipping for Chiller Condenser Tube Cleaning

We keep tube cleaning equipment in our stores in Jeddah, Saudi Arabia which we ship to our Middle East customers. We also have tube cleaning equipment in our stores at Head Office in Manchester, UK. We use a pallet shipping company based in Rochdale to ship parts, materials and equipment overseas. Therefore, we packed all of the necessary equipment on to a pallet, then shipped it to Cadiz. For the consumables used on the job, we have suppliers in Spain, but we usually prefer to ship these smaller things from the UK along with the equipment. This is because our engineers are more used to the brands and types of consumables that we get from our UK suppliers.

RAMS for Chiller Condenser Tube Cleaning

All of our paperwork, Tick Sheets and Risk Assessment Method Statements have been professionally translated into Spanish. Therefore, our Spanish engineer carried out a site survey to assess the risks, he then sent a report to Head Office. We decided upon the appropriate measures to control the risks, then sent the RAMS to site prior to the visit.

Permit to Work for Chiller Condenser Tube Cleaning

The onsite health and safety officer looked at our RAMS and decided how to compose his Permit to Work. Then, both of our engineers signed it at the start and at completion of the job.

Walk Round before Chiller Condenser Tube Cleaning

On completion of the paperwork, our engineers, the onsite health and safety officer and an onsite engineer had a walk round to assess the job. This was to make sure that all was okay to carry out the tube cleaning.

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Chiller Condenser Tube Cleaning Operation

Each of the 4 chillers was worked on in turn in the order as described above.

Valve Configuration

Each condenser was valved off with the configuration of the pipework changed. This was to ensure that the flow rates were correct for all 4 of the chillers. Otherwise, a catastrophic failure of the chillers could occur.

Drain Down

The condensers were then drained down and vented using a selection of fittings that were shipped out with our equipment.

End Plates

Our engineers unbolted the end plates and lifted them to the side using specialist lifting equipment.

Tube Cleaning

In Spain they just use a 220v supply for electrical equipment instead of the 110v equipment that we commonly use in the UK. As our equipment is 110v, we shipped our transformer on the pallet. Once the equipment was set up- we carried out the cleaning of each condenser tube according to standard industry guidelines.

Rebuild

The seal on the end plates is prone to leak after breaking into the system so we shipped replacements from Head Office. Our engineers found it a fiddly job as the new seals had been folded up in a different position in the packet. This meant that they kept jumping out of the grooves. When the seals eventually remained in the grooves, the end plates were bolted into position according to the correct torque setting.

Air Purge and Valve Configuration

The air was purged from the shell of the condensers and the valve configuration was returned to the original position.

Test Operation

Each of the 4 chillers was run tested in turn and the system readings were recorded on our paperwork. A dramatic increase in performance was recorded on each system. The refrigerant pressures and temperatures were a lot better and the coefficient of performance was markedly higher. This means a lower carbon footprint and lower electricity costs.

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Offshore oil rig showing chiller service being carried out in marine environment

Offshore & Marine Chiller Service

North Sea Offshore & Marine Chiller Service

On a previous visit for offshore & marine chiller service on an oil rig, our customer had shown us to a large air cooled chiller. His complaint was that it was tripping out all the time when there was nothing wrong it. Complicated ‘in house’ controls, where a string of PCBs, plugged into each other were found in the panel. We recommended a controls retrofit and received the order to carry out work…

Finicky Controls

All of the finicky control PCBs were removed from the panel and placed in the electrical recycling skip.

Offshore & Marine Chiller Service to Control Wiring 

The control wiring was removed and grouped together according to colour. This was because the same wiring was going to be re used to re wire chiller.

Inverters

Two Danfoss inverters were installed into the panel. These were to provide a VSD (variable speed drive) for two large screw compressors.

Electronic Expansion Valves

Danfoss EEVs were easily brazed into place as both systems could be pumped down and valved off. This part of the fridge system was then nitrogen pressure tested then vacuumed according to standard industry guidelines.

Fan Speed Controllers

Both systems had a Danfoss fan speed controller fitted to the chiller frame to control the condenser fans. Then, the control transducers were wired in to the FSCs. This made them stand alone and capable of independently controlling the head pressure of each system.

Danfoss Chiller Controller

The controller in the photo is capable of running the inverter drives for the compressors and the electronic expansion valves. It was wired in, one wire at a time: first the Inputs, then the Outputs and finally the power supply.

Offshore & Marine Chiller Commissioning Service

We always carry out commissioning in the morning as this is the best time of the day to solve problems. It was time for a cup of coffee and a deep breath. Our engineer had only re wired one panel previously and he was also a long way from the office.

Switch On

When he switched the power supply on, there were no immediate problems, so he waited for the for the timer to count down. System 1 started and after a while System 2 started too. There were a few teething problems with the settings, but then the chiller settled down. No more spurious trip outs.

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Controller used in offshore chiller service
Cheap and very reliable

Offshore & Marine Chiller Service in Liverpool

A bulker had got into difficulties in the Irish Sea and been towed to Liverpool for service. It was discovered that a rope had got wrapped around the propeller. Aside from this, one of two chillers which are used for the cooling of the living quarters had tripped out. The Chief Engineer had therefore decided to kill two birds with one stone. Most of the crew were from around Tanger Med in Morocco and so spoke only a little English. They also have limits as to how far they will go with a fridge system. Not to worry though: all we need is to see the plant and we can take it from there...

Seawater Cooled

The plant had a sea water cooled condenser which was fed via a pump set in an adjoining plant room.

Offshore & Marine Chiller Service to Controller

The controller alarm message stated that there was a low pressure condition in the evaporator. On interrogation of the menu, however, the pressure of the evaporator was found to be 7 bar which was the same as in the condenser.

Reset

Our engineer therefore decided to follow through the reset procedure. The alarm cleared and the machine started up. Then, it pumped down to 1 bar and tripped out on the same fault.

Liquid Line Solenoid Valve

While this was happening, our engineer was quick to notice that the liquid line solenoid valve had not activated. He decided to manually jack it open with his test equipment and the refrigerant rushed through okay.

Liquid Line Solenoid Coil

Having decided that the valve was okay, he then investigated the coil. The connection box and the wiring was found to be in poor condition.

Isolate

He then isolated the power supply and checked that it was dead.

Rewire

The wiring was cut back and he re made the connections onto the solenoid coil without using the connection box. Then, he insulated the area with a special compound.

Test Operation

Now to see if he had got the diagnosis correct. He powered up the chiller and carried out a run test- all readings were found to be nominal and the machine went back into service.

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Planning for Offshore & Marine Chiller Service

The main part of the planning for an offshore visit is done on the previous job. A detailed list of the required parts, materials, refrigerant, tools and equipment is composed on our Offshore Manifest Sheet. The questions and headings have been designed to prompt an engineer into thinking about all aspects of the job in detail.

Preparation for Offshore & Marine Chiller Service 

Having emailed the above mentioned sheet to Head Office, we cross reference the information with the engineer while he is still offshore. All this preparation is to ensure that the upcoming job goes as planned. There would be nothing worse than to have to postpone the job due to a lack of preparation.

Steel Chests

We have several steel chests that we use for shipping to oil rigs. After the parts and materials arrive at Head Office, they are checked off, one at a time into the shipping chests. Then, the necessary tools and equipment is checked off too.

Offshore Stores

Our customers also have their own equipment in their stores. They have things like fittings and fuses too. This is a good backup for when something is unforeseen, or if something breaks.

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Man commissioning a chiller in Saudi wearing head gear

Saudi Chiller Commissioning

We arranged the trip to carry out Saudi chiller commissioning for our Company Director and overseas engineer Dave Thompson. 2x 500kw air cooled chillers had been positioned at high level on a gantry. These were at the back of a newly constructed building at a factory in Jeddah. The factory produces plastic water pipes used for buildings and industry. Their own pipework, produced onsite, was used for the water systems of the plant in this article.

Water System Check Valves

There are two underground water system reservoirs for the plant. A check valve is fitted below the water line on the inlet pipe feeding all of the pumps. This ensures that water is available to the pumps on start up, despite the reservoirs being below the pumps.

Saudi Chiller Commissioning of Chiller Pump Set

The chiller pump set sucks water from the underground chiller reservoir. It then discharges the water through a plate heat exchanger, then it flows up to the chillers. The chilled water then returns 5°C cooler back to the underground chiller reservoir.

Saudi Chiller Commissioning of PHE Pump Set

Another pump set sucks from the separate underground process reservoir and discharges through the other side of the above mentioned plate heat exchanger. The water is chilled by around 5°C which can be adjusted with a pressure regulating valve on the outlet of the PHE. This chilled water then returns to the underground process reservoir.

Saudi Chiller Commissioning of Process Pump Set

A third pump set also sucks from the above mentioned underground process reservoir. It then discharges up to a ring main which goes along the top of 6 lines. Then, it drains down into plastic extrusion moulding machines to cool the newly formed plastic pipe. It does this at just the right rate to prevent bending and distortion. After this, the chilled water drains at gravity pressure back into the underground process reservoir.

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Control Panels for Pump Inverters

All of the pumps run on inverter drives which saves a significant amount of electricity. These drives are located in three panels- one for each pump set. A spare inverter is available in each panel for easy switch over in the event of failure. A touch screen pump control display is fitted to each panel. Each display is wired into a PLC.

Touch Screen Central Control

The PLCs in each panel are in turn wired into a Schneider Electric touch screen central control interface. This is located on the front of the middle panel. All of the analogue sensor and transducer inputs are wired into this interface from around the plant. The underground process reservoir temperature sensor was found to be reading 4°C high, so an offset was put into the program. The digital outputs go from here to the various components around the plant.

3 Way Valve

One of these components is a 3 way valve on the plate heat exchanger. This valve regulates the percentage flow of water through the PHE, relative to the percentage of bypass to the chillers. In high load conditions, 100% of water is pumped through the PHE. With no load, 0% of water goes through the PHE with full bypass to the chillers. In a low load condition, the valve modulates at between 0% and 100%. All of these scenarios achieve a close control at 20°C in the underground process reservoir.

Saudi Chiller Commissioning of Filtration Systems

Chiller Evaporators

The chiller evaporators are protected by a ‘y’ strainer on each inlet.

PHE Chiller Side

The plate heat exchanger also keeps contaminants from the process reaching the evaporators of the chillers. This prevents the premature failure of the evaporators and also prevents heat exchange issues due to thermal insulation.

PHE and Process Bollfilter

Both of these water systems go through a Bollfilter back flush system. As the difference in pressure between filter inlet and outlet reaches a predetermined level, the back flushing operation is initiated with a green light being illuminated. This feature prevents the need to manually clean the filter at scheduled intervals. During the visit, however, these filters were overwhelmed by the residue left in the pipes and a narrow 100 micron filter size. The maximum difference in pressure was exceeded and the filtration system yellow warning light became illuminated. The filters were stripped down, cleaned and reassembled.

‘Y’ Strainer in Parallel

The onsite engineer who had assisted in designing the system had the foresight to build a second filter into the water system. This ‘y’ strainer runs in parallel to the above Bollfilter and ensures seamless operation of the factory in the event of a blocked Bollfilter.

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Start Up during Saudi Chiller Commissioning

On first start up of the chillers, they were both found to be tripping on high pressure and not loading up. The chillers run on R134a which is a low pressure refrigerant in the UK. In Saudi Arabia, however, the ambient is around 40°C. This translates to an operating pressure of between 15 bar and 18 bar depending on loading and water temperature.

Loading Solenoids

Unloader switches are available on each system. These feed back to the PLC, from here the program energises the loading solenoids. They had been set to 14 bar which was the cause of the unloading issue. Our overseas engineer set the switches to 19 bar.

High Pressure Switches

He then changed the high pressure cut outs from 15 bar to 20 bar.

PRVs Checked during Saudi Chiller Commissioning

The pressure relief valves vent at 23 bar which is enough of a difference in pressure from the high pressure cut out.

Low Load Trips

Because only one line was running at the time of commissioning, one of the chillers was found to have tripped on a low temperature related trip. This fault had occurred the following morning when the water temperature had become too low due to the minimum run time of the compressors. The freeze up set point was also found to be too high at 7°C. Our overseas engineer entered a password into the front end of each chiller and modified the parameters to prevent this fault re occurring.

Full Load Testing

The water system temperature was allowed to build up to 30°C when production in the factory was offline. Then, the chillers were ran in anger until set point was achieved. An efficient superheat value of 3°C was recorded on all of the systems. This is due to electronic expansion valves being fitted. When the factory came back online, the systems were found to be off cycling or unloading to match the load.

Chiller Redundancy

Redundancy has been considered in the capacity of the chillers to allow for future factory expansion and systems being offline during repairs.

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Global chilled water system service near Saint Basil's Cathedral

Global Chilled Water System Service

Moscow Visit

Always good for our engineers to get out of the country to carry out global chilled water system service. He just had a little free time this visit to see Red Square and Saint Basil's Cathedral. Most of the visit was bogged down resolving issues.

Electrical Problems

One of the chillers was pumping down due to electrical problems. One of the solenoids for the evaporator was not opening. All checked out okay with the solenoid coil and valve. Following the wiring diagram led to the relay board. The relay board is responsible to run various components around the compressor. It was not obviously blown and there were no dry soldered joints on the back. Our engineer decided to tighten up the wiring and unplug, then plug all the connectors back in. When he ran the chiller again the problem went away.

Chilled Water System Global Service

As we provide a global service: we cannot get back the day after leaving site. Therefore, after resolving the above issue, our engineer ran the system in local with some of the other systems off to prove it. All was okay. After completing the rest of the service on the chillers, he put the whole of the plant back in Auto to prove it all together.

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Flow Switch Failure during Global Chilled Water System Service

Due to security issues, this one of the most remote plant rooms for a flow switch to fail. The chiller did not stop when a test was carried out. Our engineer did not want to valve off the water system as the air handlers are old and 'dead heading' could cause failure. Instead, he decided to use the Hand/ Off/ Auto switch for the pump. After several attempts of trimming, he got the switch to settle down, then carried out tests to make sure it would not happen again.

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