Author Archives: Maximus Chillers

Two dark green centrifugal chillers undergoing maintenance in plant room

Centrifugal Chiller Maintenance

At the beginning of the year we completed centrifugal chiller maintenance for one of our customers in America. A last overseas trip for the moment given the current world lockdown. The chillers in the photo chill water that is pumped around a university campus

Centrifugal Chiller Maintenance of Redundant System

The plant has been designed according to the N+1 principle: N being the amount of cooling required and 1 being that same amount of cooling again. Each chiller has enough capacity to satisfy demand. Given the large size of the campus, this principle was critical to keeping the University functioning should system failure occur. The chiller on the right was the lead chiller on arrival. After taking detailed readings during the maintenance, our engineer switched that chiller over into being the lag chiller and took readings from the chiller on the left. He rotates the lead/ lag of the chillers on each visit to balance the run hours of the compressors

Volumetric Efficiency

Centrifugal chillers have a lower volumetric efficiency compared with positive displacement compressors such as screws and repips. This is because the impeller does not mechanically compress the refrigerant like a piston in a reciprocating compressor. This kind of compressor relies on centrifugal force to spin the refrigerant off the tip of the impeller and onto the next stage. The refrigerant is then discharged from the compressor

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Mass Flow Rate

The above is more than compensated for with a high mass flow rate. That is to say: a high volume of refrigerant circulates around the system at its operating density. A large capacity machine is cost effective when considering energy efficiency and centrifugal chiller maintenance costs

Gantry Crane for Centrifugal Chiller Maintenance

The gantry crane in the picture is available to aid with the lift and shift of the compressor, should compressor failure occur. Maximus Chillers are specialists in the overhaul of centrifugal compressors. We can arrange the lift out, transportation, strip down and reassembly of your compressors. All of our strip downs come with a 12 month warranty to give you peace of mind and confidence in our ability

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Follow this link to read about centrifugal compressors at The Engineering Mindset | Click Here


R134a chilling plant maintenance showing screw compressor and oil separator with tick sheet and digital thermometer on top

R134a Chilling Plant Maintenance

We recently carried out R134a chilling plant maintenance at our customer’s factory in the North West. The chiller is 600kw with 2 single compressor systems. It has an ‘in house’ controller on it with occasional spurious trip outs. We are working with the problem so far, but an option if the problem persists is to fit a reliable, cheap, off the shelf controller. The factory requires a process water temperature of 6°. The plant is around the middle of the lifespan and has been properly maintained

R134a Chilling Plant Maintenance Checks

Unlock Controller

The customer had accidentally locked the controller by pressing the wrong buttons. The machine still functioned as it should, but the customer was unable to modify User settings or look at the readings. Our engineers carry a book with an extensive list of information for any controller which has been built up over time. The procedure was followed to unlock the controller, then the settings were checked

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R134a Chilling Plant Sensor Maintenance 

The sensors can be offset to compensate for a sensor reading out slightly. No offsets were saved and the sensors all read to within a degree or two of our digital thermometer. Our engineer then checked the sensor locations to ensure they were fitted correctly and insulation had not deteriorated

Fan speed Controllers and Subcooling

During the R134a chilling plant maintenance, particular attention was paid to the fan speed controllers and the subcooling of the refrigerant. This is because of occasional spurious high pressure trips. All the wiring was tightened and the plugged connections were checked and tested. The controller sends a variable run signal to the fan speed controllers. This is worked out from the analogue input signal from the high pressure transducer. If the problem persists, we will have to look into fitting more reliable head pressure controls

Compressor Slide Valve

The oil solenoids which push and pull the compressor slide valve were operating correctly. The controller sends volts to the solenoids to control the position of the valve. A slide valve sensor sends feedback so the controller can work out the percentage position of the valve

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Follow this link to read more about pressure sensors on Wikipedia Click Here


Air cooled chiller planned maintenance showing both economizers with solenoid valves and expansion valves

Air Cooled Chiller Planned Maintenance

An air cooled chiller planned maintenance visit for a long standing customer of ours. They have just signed up to another 3 year contract. We know at Maximus Chillers that if we want to keep our customers, we must continue to offer the Maximus Service. Maximus is Latin for the highest and the greatest

Planned Maintenance for Air Cooled Chillers

Planned maintenance is essential for these air cooled chillers as they are critical plant. They feed a large conference room which is a major part of the end user’s business. They can’t afford to loose the conference room when there is an event on. There is redundancy in the plant, but the customer always makes sure that the issues highlighted on the planned maintenance are acted on promptly. Also, the chillers feed a water cooled condenser for a pack which cools £50,000 of products used during the conferences

Air Cooled Chiller Oil Planned Maintenance

1mw of cooling across 2 air cooled chillers were undergoing planned maintenance. Our engineer noticed that the oil level was slightly below the sight glass on one of the 250kw Bitzer compressors. The machine had previously been extensively run tested to ensure no oil return issues were present. Therefore, he decided to adjust the level with the oil available onsite

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Economiser

The economisers, in the picture, were tested to ensure the solenoids were opening when the program sent the run signal. The electronic expansion valves functioned correctly and subcooled the liquid further after the condenser

Head Pressure Control

The head pressure control was functioning correctly, keeping a steady 8 bar of pressure across all stages of loading and water system temperatures. This is because these chillers use a fan speed controller for each system. The fans cut in at the minimum running speed, which prevents stalling and over heating. Also, all fans running together are more reliable. Fans fail on systems using relays or pressure switches as the higher pressure fans don’t often come on. When they do, moisture has ingressed into them causing them to fail

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Follow this link to read more | Carel cut phase speed controllers


Yellow oil drums, ammonia refrigerant cylinders and flammable flushing agent of chiller refurbishment supplier

Chiller Refurbishment Supplier

Maximus Chillers is an established chiller refurbishment supplier. Maximus means the highest and the greatest in Latin, so we pride ourselves in offering the highest and the greatest customer service and technical capability. There is never a job too big for Maximus Chillers- we are seasoned in following a problem through to the logical solution

Chiller Refurbishment Supplier

Parts

Any part is available to our contract customers. We have a worldwide supply chain of the best suppliers. This means any part or refrigerant can be sourced at your convenience. When a part is not available, a different part of the same design specifications is selected and usually delivered same day. By same day we mean: the part is loaded into a van- then and there- and driven to site!

Oil and Refrigerant

We keep a stock of oil, refrigerant and other materials in our stores- see picture. This provides you with 'round the corner' convenience to your factory or facility. Whatever kind of ammonia grade specialist oil you require- we have it on the shelf. With a comprehensive range of other chemicals and solvents- Maximus Chillers completes the picture

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Chiller Refurbishment Fault Finding

Our engineers are in their comfort zone while carrying out fault finding during chiller refurbishment- that is what they do best! Even when a fault involves wiring that disappears into a loom, down the other end of the machine, with no wiring diagram- Maximus Chillers can help. Usually, however, faults are obvious to our engineers or can be found easily

Technical Support Desk

Our contract customers enjoy the full benefit of our global technical support desk. We offer real time technical support with manuals being sent electronically to site. Where a time difference is involved, we arrange a time convenient to both locations, or answer emails when the office opens in the morning. If we can talk you through over the phone, we can get you up and running with the minimal disruption to your process

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Visit the ASHRAE for Standards and Guidelines Under Continuous Maintenance


Frost covered blue oil return vessel during the removal of industrial refrigeration sludge

Industrial Refrigeration Sludge

This industrial refrigeration visit is to remove sludge from the system. There had been a long period of neglect prior to Maximus Chillers attending site, so regular oil changes had not been carried out. Two oil changes have now been carried out and still a small amount of sludge still remains in the system

Industrial Refrigeration Sludge

Due to previous industrial refrigeration sludge removal, the plant was down to about half of its 60kg charge of refrigerant. It was starting to show signs of refrigerant shortage as the machine was preventing loading up. An ammonia suitable pump out unit was used to decant the remaining refrigerant into a cylinder for disposal

Pressure and Temperature

Once this had been carried out, any residual refrigerant in the oil and liquid on the low side of the plant was carefully handled until the plant was at the same pressure and temperature of the surrounding environment. See picture of some remaining liquid boiling off in an oil return vessel on the bottom of the flooded evaporator

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Industrial Refrigeration Sludge Oil

Once the pressure and temperatures equalized, our engineer drained the oil in the system from four different vessels. The oil was then removed from site for recycling. Usually, pressure helps with the process, but as the system was empty, gravity was sufficient for most parts of the plant. Nitrogen being introduced to the oil supply pipe to push it back to the oil separator

Flushing Agent

A flushing agent specially formulated for use in ammonia systems was used to aid the removal of sludge and oil from the pipework around the chiller

Evacuation

After a pressure test, the evacuation process was started. This was to boil off any remaining flushing agent, to remove non condensables and remove any moisture. A near perfect vacuum was achieved

Run up

New refrigeration grade anhydrous ammonia was charged into the system, a little at first to check for any leaks. Then, the plant was checked for effective running conditions. All readings were okay with the compressor loading up to 100% before backing off to match the load

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Read more about oil analysis and testing at the Institute of Refrigeration | Click Here


Green chiller panel with doors open, showing contactors and PCBs during water chiller maintenance

Water Chiller Maintenance

Maximus chillers provides water chiller maintenance to all kinds of machines. Some of which have kilowatt hour meters fitted. This means we can monitor the reduction in energy consumption, directly as a result of our maintenance being carried out

Efficient Water Chiller Maintenance

Maintenance is carried out to ensure every aspect of your water chiller is running efficiently. We believe our Tick Sheet is the best in the industry. It looks in detail at the running conditions of the plant, component adjustments and the parameters in the controls. The Tick Sheet is used to assess if there are problems that are starting to occur before a safety shutdown happens. Below are some of the issues that we keep on top of to increase the efficiency of your plant

Shell and Tube Insulation

The build up of dirt acts as an insulator in shell and tube heat exchangers. These are used for the evaporation and the condensing of the refrigerant

The Evaporator

In the evaporator, should the tubes be fouled, there will be a reduction in heat absorbed into the system. This will cause the plant to stay on longer and use considerably more energy. Should the tubes become considerably fouled, the water chiller will malfunction and eventually system shutdown will occur

The Condenser

In a shell and tube condenser, the reverse of the above will occur. Tube fouling, acting as an insulator, will prohibit the rejection of heat from the system. The head pressure control will open the condenser controls to try and assist in heat rejection. Heavy fouling will cause an increase in the consumption of energy. Eventually a safety shutdown will occur causing loss of production

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Compressor Loading

Should the loading of the compressors be found to be faulty. The plant will not be able to effectively match the load

Over Loading

Too much loading may occur, causing the water chillers to achieve set point too quickly. The plant will then go through the off cycle. This means that the plant will have to load back up, using more energy than matching the load continuously

Under Loading

Should the plant be unable to load up to the required level to match the load, this will cause the water temperature to creep up and the lag chillers being called for to match the load. More water chillers running than necessary dramatically increases energy consumption

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Visit the Refcom site to read about leak checking during water chiller maintenance | Click Here


Process chiller maintenance visit showing refrigerant gauge lines fitted to a grey chiller

Process Chiller Maintenance Visit

Maximus Chillers recently carried out a maintenance visit to an Italian process chiller

Process Chiller Maintenance Visit for Water Level Sensor

The process chiller has a water treatment schedule, but on this visit, the water level sensor needed maintenance. This is because the three probes of the sensor were not completing continuity. The probes complete the continuity from the wire going into the sensor, along the probe, then to another wire completing continuity back to the controls of the chiller

Low Water Probe

If the controls loose continuity to the low water probe, the alarm is triggered and a call out is arranged to resolve the issue

Correct Level Probe

In normal operation, the correct level probe is activated and the chiller runs as normal

High Water Level Probe

Should the high water level probe be activated, again the alarm is triggered and a call out arranged

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Maintenance Visit to the Process Chiller

As we were already on site to carry out the maintenance, there was no need to arrange a call out. We soaked the sensor for an hour in a special a decontamination chemical that has been designed to restore the probes. That done, the rest of the maintenance was carried out including the tightening of the wiring and motor connectors. It was possible to do this on this visit as the factory was not in production

Run Testing

All readings around the chiller were taken when the factory went back into production. We found the fridge system to be working with optimum efficiency, meaning that the chiller will use the optimum amount of electricity. Efficiency is a great concern to a factory as they want to reduce their carbon footprint as much as possible

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Follow this link for the IOR celebration of chiller service engineers | Click Here


Chilling plant service showing yellow top recovery cylinder with gauge line and sight glass fitted

Chilling Plant Service

Our customer had been having high pressure service problems on his chilling plant

Transducer Required Chilling Plant Service

The 4-20mA transducer needed service on the chilling plant. It was reading low by a long shot. Therefore, the PLC was not bringing the fans on as it should. The pressure in the high side of the system was getting up to 40 bar. This is because the refrigerant was R410a- it has a higher head pressure than other commonly used HFC refrigerants, such as, R407c. We ordered the replacement transducer which is fitted with a female fitting

Chilling Plant Service Leaks

He concentrated his attention on the high side of the system to start with. Then, found a leak on a fitting, a leak on the pressure relief valve fitting and a leak on the liquid line near the drier. A sealant was used for leaks on the fittings- they were removed, cleaned and refitted. The leak on the liquid line was re sealed by removing the section of pipe, removing any remaining solder then the section of pipe was re made

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Pressure Test

The remaining parts of the system were leak tested then the chilling plant was put on a pressure test to ensure the whole system was leak free. The pressure test was satisfactory and so the evacuation process could be started

Evacuation Process 

Each of our engineers has a powerful vac pump to speed up the dehydration process on the chilling plant being serviced. This means that a deep vacuum can often be pulled on the same day instead of the usual overnight process. The nitrogen and other non condensables were removed quickly and the Torr gauge came down to the pressure where moisture was being removed. At this pressure, any moisture is forced to boil off around the system

Recharging of the Chilling Plant Being Serviced

In the photo, the chilling plant is being recharged at the end of the service work. It is being recharged into the liquid side of the evaporator. All readings were okay when running the system and further leak tests were carried out at normal operating pressures

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Read more about refrigerant reclamation by following this link to Wikipedia | Click Here


A chiller condenser retrofitting lifting operation outside in the compound

Chiller Condenser Retrofitting

We recently undertook the job to carry out bespoke chiller condenser retrofitting in the North West

Rusted and Corroded Condenser

The old condenser looked alright on the surface- the fins were in good condition. The chiller condenser was 18 years old and when an attempt to repair a leak was carried out- the condenser leaked further along. This is because of the warming of rusted and corroded copper with an oxy-acetylene torch

Chiller Condenser Retrofitting

We arrived on site to measure up for the job. The ‘V’ chiller condenser being retrofitted was built to order. We manufactured an exact replica to the same specifications and sizes of the old one. The operating pressures and high pressure cut out limit were taken into account in the design and the use of materials

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Lift Out of Chiller Condenser being Retrofitted

On the day of the lift and shift we isolated the panel and checked it was dead, then we removed the panel and laid it on it’s front. This was to access the rivets behind the panel. These rivets, the ones on the other end of the chiller and around the lid were removed using a tool. The fans were disconnected and removed to make the lid lighter to lift off. Then, we attached slings to the chiller condenser and lifted both halves of the 'V' out

Lift In of the Chiller Condenser being Retrofitted

This part we did not want to get wrong as the chiller condenser being retrofitted was brand new and did not have a mark on it. A reverse of the removal- it fitted perfectly just the same as the old one. With the lid lifted back on and the fans in- time for brazing then the pressure test

Pressure Test, Dehydration and Recharge

The pressure test was satisfactory so our engineer put the system on vac for dehydration purposes and the removal of non condensables. After a deep vacuum was achieved the system was recharged and run tested. No issues were found

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Read more about air cooled condensers at the Institute of Refrigeration Click Here


Ammonia refrigerant cylinder being winched up a cat ladder using a block and tackle

Industrial Refrigeration Ammonia

The industrial refrigeration ammonia visit was in Aberystwyth. We look after 2 ammonia chillers on site. They are 10 year old chillers that have been designed to need ongoing attention. Quite easy job as the faults they go into are reoccurring round in a circle. They have previously had the same problems

Ammonia Shaft Seal for Industrial Refrigeration

The industrial refrigeration shaft seal had started to leak ammonia. It was replaced by removing the shaft seal cover, splitting the coupling and sliding the shaft seal over the shaft. After removing the non condensables, we reintroduced the ammonia back into the compressor. The 'o' rings leaked

Leaking Industrial Refrigeration Ammonia 'O' Rings

Ammonia leaks of industrial refrigeration ‘o’ rings occurs because they become flattened and plastic like. This is caused by heat around the high side of the screw compressor. When there is pressure in the system- the oil if forced against the gap- making a seal. After the ammonia refrigerant had been handled- the oil ran away- causing the leak when the ammonia was reintroduced

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Lift and Shift for Ammonia Visit

The pipework and ancillaries had been removed from the compressor prior to the ammonia visit. Our lift and shift guys arrived and set up their lifting equipment. They raised the compressor and manoeuvred it on across the roof. They then manoeuvred it up then down some steps. They used lifting equipment to get the compressor, end on- down a cat ladder

Tear Down of the Ammonia Screw Compressor

It is always better to tear down this kind of compressor in a workshop- on a bench with compressed air and all the tools nearby. We unbolted the castings and slid the screw out. The various castings being laid out in a line. We replaced the ‘o’ rings for new the rebuilt the compressor

Industrial refrigeration ammonia being charged by an engineer wearing breathing apparatus and gloves
Ammonia refrigerant being sucked into the low side of a flooded evaporator

Ammonia Refrigerant Charge

Part of the ammonia refrigerant had been handled during the visit. This left the compressor pipework, compressor and the oil separator open to atmosphere. The non condensables were evacuated. In the photo we are lifting the cylinder up a cat ladder into the plant room. From there it needed to be man handled up some steps, down some steps and out onto the roof. We charged the ammonia plant with liquid ammonia until the superheat and subcooling values were within industry known limits. The sight glass levels and condition were monitored too

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If you would like to buy an introduction to ammonia refrigeration from the iiar Click Here


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