Chiller Repair Service

New fan decks being lifted onto ammonia chiller during chiller repair service

Chiller Repair Service

An effective chiller repair service is what you need to get you up and running- fast! Here at Maximus Chillers, no job is too small, or too big. We have the capability to do anything from replacing contactors to centrifugal compressor remanufacturing- we are a one stop shop for all of your needs.

News Article No.26

Customer Orientated Chiller Repair Service

We also know the reason why we are an expanding company: you- the customer! Listening to your requirements goes a long way to help us achieve your objectives. We assign the same engineer to each site, so that you have the chance to build up a relationship and he gets to know your plant. Read on for an insight into some of the repairs that we carry out…

All new fan decks in place on large air cooled chiller during chiller repair service
Fast supply chain for retrofitting fans

Fan Deck Retrofitting Chiller Repair Service

The photos show the fans being lifted up, then when they are in position on a 200kw ammonia chiller. The fans had been failing one at a time until the chiller started experiencing high pressure trip outs. Action was not immediately taken because there were insufficient funds in the customer’s budget. When the customer was allocated a new budget, they gave us the Order to carry out the work. We decided to change all 8 fans.

Odd Size

The old fans were 790mm blade diameter instead of the standard 800mm. Manufacturers ask suppliers for odd sizes and specifications along with an OEM data plate in an attempt to monopolise the customer. A bonafide chiller company, however, is adept at making square pegs fit round holes. Not really a round hole though with this one- we just plonked our fan decks on top where the old ones had been fitted.

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Refrigerant Leak Chiller Repair Service

HFC refrigerants are becoming more expensive due to the HFC phase down. Therefore, as well as the environmental cost of a leaking chiller, there is the cost on your pocket too. At Maximus Chillers we find the root cause of the leak instead of just brazing it up. Some of these causes are:

Condenser Vibration

Some head pressure control systems bring the fans on, forwards and backwards in different stages. This causes the chiller frame to judder and vibration related leaks to occur on the condenser. The solution is easy- fit stand alone fan speed controllers.

Compressor Vibration

Some chillers are designed to fit into a small footprint of space. A good example of this is a particular model of laser chiller that had been designed to fit down the side of a laser cutter. That’s alright until, years after production, reoccurring leaks start happening around the compressor. There is no room to fit vibration eliminators, besides, they only work if they are fitted horizontally and vertically with the far end being clamped. Brazing the leak up just causes the already work hardened copper pipe to further anneal and become even more brittle- another leak will happen shortly there after. The solution is to remove the whole piece of pipework, go up a pipe size and replace it with new.

Component Failure

We find some components are flawed and are prone to leaking. An example of this are refrigerant hoses which are prone to rubbing through against the chiller. The solution is to fit anacondas or static copper pipework.

Reduced Service Costs

All of these measures and more are how we reduce the frequency of refrigerant leaks on your plant.

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Compressor Remanufacturing Chiller Repair Service

Weather you have scroll, reciprocating, screw or centrifugal compressors, we have the capability to get it out, rebuild it and get it back in again. With same day delivery of internal compressor components- we won’t keep you waiting around. Our expert team are adept at ensuring that your compressors are rebuilt with minimal run out and have clearances that are within tolerance. All bolts are touqued up to the correct setting too. The last part of the job is the compressor paint re spray to the same colour as before, or to our standard battleship grey.

Controls Retrofitting Chiller Repair Service

When a controller fails it is often found to be obsolete. Don’t worry because we can fit a new controller to any machine. For HFC chillers we fit Carel controllers, we fit Beijer Electronics to ammonia chillers and MCS controllers to centrifugal chillers.

Strip Out

The easiest way to do a controls retrofit is to start all over again from scratch. We remove the defunct controls from the panel and pull all the control wiring out too. We leave the three phase wiring in place, the contactors and the common neutral.

Rewire

One wire at a time, we rewire the chiller. All of the analogue inputs are wired in along with the digital inputs. Then, the outputs are wired to the contactors and relays. The transformers in the panel are often reused to get the various voltages that are required for the new controller, contactor coils and relay coils.

Commissioning

The new controllers come pre set with default parameters so only minor adjustments are needed to get the chiller to settle down. We then spend the rest of the day monitoring the chiller so as to watch it running in the various stages of loading and under different running conditions.

Chiller Repair Service that is Second to None

The above examples are just an insight into our extensive range of capabilities in the repairs of your plant. Basically- if you have a problem- then we have a solution. This is just part of what we call the MAXIMUS ADVANTAGE™ Any Chiller- Any Problem- Any Part- Any Refrigerant- Anywhere. With customers around the world in places like Saudi Arabia, Spain and the United States of Amarica we continue to exceed the expectations of our customers. We have a network of engineers around the UK too, so we are never farer than a couple of hours away. For the best service, the choice is clear- Maximus Chillers!

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Hit the Tags at the top of the page to navigate your way to our extensive library of further reading on this subject.

Read more about refrigerant leak causes & tests at Herzing College.


6 large air cooled chiller condensers maintained with 12 fans each

Air Cooled Chiller Condenser Maintenance

The photo is showing air cooled chiller condenser maintenance being carried out by Maximus Chillers. 6 water cooled chillers are located in the plant room below. They are 750 kw single screw compressors with a control panel located to the side of each. On this visit, the emphasis was to carry out a thorough maintenance of the condensers.

Fan Speed Controllers

The refrigerant for the systems is R134a, so to allow for the saturation of the refrigerant, 8 bar is the head pressure set point. This pressure corresponds to the desired condenser temperature of 36°C. Subcooling of 6°C to 8°C is achieved during the nominal operation of the plant. Each fan speed controller runs the 12 condenser fans together. Other condenser designs where fans bang on forwards and backwards cause vibrations resulting in reoccurring leaks on the condenser. Chiller No. 2 had tripped during a 'discharge override' system message. On inspection of No. 2 condenser- the fans speed inverter had tripped on 'over temperature' alarm. The panel fan, which is the kind to cool computers, was found to be still trying to run but seized. This failure had caused the alarm on the inverter. The panel fan was replaced from the stock of parts in the onsite stores. The chiller was reset and a detailed Tick Sheet was completed noting the occurrence of this fault on arrival.

Air Cooled Chiller Condenser Maintenance Cleaning

Because of the large size of the plant, the customer had installed a fireman’s hose for the cleaning of the condensers. This is located in the free space beneath the condensers. It is fitted to a portable buggy so it can be moved under each condenser. Setting the nozzle to the correct attitude, our engineer moved the buggy sideways, so as to rinse the condenser in the direction of the fins. The condenser was relatively clean as the onsite maintenance engineers carry out this task as part of their monthly schedule.

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Design Considerations for Air Cooled Chiller Condenser Maintenance

The kind of condenser in this article is:

Multiple Row Tubing

3 Rows

It has tubing of ½” diameter which is 3 rows deep. Each pass starts at the discharge header which is at the inlet to the condenser, goes down to the far end, through a condenser end turn, back to the discharge end, through another condenser end turn and back again to the liquid pipe end. The heat removed from the condenser, per kg of refrigerant, is the heat content of the vapour as it leaves the compressor, minus the heat remaining in the liquid at the end of the condenser.

6 Rows

Some condenser designs are up to 6 rows deep. This allows a small footprint of space where there is not much room for the location of the chiller. The downside to this, is that the chiller engineer can often struggle to locate the exact location of a leak when it is deep into the coil. If a condenser is too small, it will cause a higher head pressure and reduce the life of the compressor. We can arrange the lift out and repair of deep row condensers in our workshop.

Finned

This condenser has aluminium fins which are pressed around the copper tubing. This increases the surface area of the condenser heat exchange medium and so increases the dissipation of heat. The same amount of heat delivered to a condenser from the compressor must also be rapidly removed. For this condition to be reached, enough head pressure will need to be built up so that the condenser temperature is at least 15°C above the ambient. This is why the same chiller can be picked up and shipped to the Middle East and still work. It will just run at a higher discharge pressure/ temperature. There will, however, be a loss in the coefficient of performance as the higher pressures will result in more electricity in, versus the same amount of refrigeration effect out.

Forced Convection Type

The fans mounted on the ducting provide this forced convection. The air is sucked through the bottom of the condenser, across the 3 rows of tubes, along the fins and up through the fans. The air flow is stable as it enters the fins so good heat transfer is achieved. As it leaves the fins at the top, there is lower heat transfer as the air is turbulent.

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Fan Replacement during Air Cooled Chiller Condenser Maintenance

Spare fans are available onsite for replacement when individual fans fail. As mentioned above, these condensers are controlled with FSC's which reduce the occurrence of leaks. As well as this, fan speed controllers increase the lifespan of the fans. Because all of the fans run together, they speed up and slow down steadily. When high pressure control switches are used, they are set at different pressures. This means that some of the fans never come on until the head pressure is too high. This is usually due to a blocked condenser, failed fans or a high ambient. Because the fans have not come on for a long time, they are often seized or have suffered water ingress from the rain. An onsite maintenance engineer is available to help with the lift out and lift in of the replacement fans.

Pressure Relief Valves

Each of these condensers is fitted with a pressure relief valve (PRV) It is fitted into the discharge pipe on the inlet to the condenser. This is so that if the fans and the HP switch were to fail, the dangerous levels of pressure in the system would be vented. It is unlikely, however, that the HP switch would fail as this is a very reliable part. A PRV being fitted is often the requirement of insurance companies. The testing or replacement being arranged at scheduled intervals.

To read more about air cooled chiller condensers click the Tag at the top of the page.

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Industrial refrigeration oil change showing ammonia warning sign

Industrial Refrigeration Oil

An industrial refrigeration oil visit was arranged because of a return issue. Several fans had been down on the air cooled system. This causes the system to unload so as to prevent a fault occurring. The lower mass flow rate of the refrigerant caused oil to migrate to the low side of the system. Several vessels are available with various forms oil return. These vessels and the oil cooler were valved off. A two man team with the correct ammonia PPE and breathing apparatus carried out the job.

Industrial Refrigeration Oil Recovery

Only some of the oil was recovered from the plant. Therefore, the engineers decided to add new oil to get the system running. The only problem with doing this is that once running the machine, the oil has to be got back out. Therefore, the oil had to be adjusted a second time to resolve the oil return issue.

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Fan Decks

For this visit, scaffolding had been erected in accordance with the Risk Assessment. The old fan decks were lifted out by the two man team. A really good team was sent out: one of the men was more technical and the other more mechanical- complementing each other with their different skill sets. The new fans were an updated version and the wiring was different. The fault link had to be adapted, but the 0-10v input from the controller was the same. The controller reads the pressure from a transducer, then sends out a voltage which the fan turns into the corresponding speed.

System Testing

The fault link had been correctly modified, so the testing of the system was carried out. The machine loaded up to 62% and monitoring continued during the rest of the visit.

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

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Chiller service of fan decks showing 8 fans

Chiller Fan Deck Service

Bodger Watch

Chiller fan deck service is usually very good, but this is bodger watch! A new customer of ours was telling us about this little guy that used to come. He was reported to have been running around like the apprentice- ringing everybody up! Then when help came, it came in the form of this huge, big man who proceeded to get stuck in the chiller! You couldn't make it up! This is bodger watch! The customer asked for a professional service from Maximus Chillers.

Repeated Leaks on Condenser

Our engineer found the head pressure control was bringing the fans thumping on and off forwards and backwards. During a visit, the fans were found to be rattling the frame and juddering the chiller into leaks.

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Learning How to Think

Instead of just swapping like for like parts. Our engineers have the capability to think outside the box and make changes to chiller design. All of our engineers attend the Maximus School of Chillers at Head Office in Droylsden, Manchester. Read More on the Chiller Company page.

Fan Speed Controller during Chiller Fan Deck Service

On a return visit, we fitted off the shelf fan speed controllers from our stores- one for each system. These fan speed controllers are stand alone- they do not need to be integrated into the existing controls. When the pressure builds up- the fan speed controller speeds the fans up from the minimum (cut in) to the maximum (same volts as the incoming supply)

Chiller Fan Deck Service for Seamless Operation

Now the fan speed controllers are fitted- there are no more leaks. Any chiller can be made to settle down into seamless operation.

Are you a factory manager or facilities manager with recurring leaks on your chillers? Need your fans replacing or the controls adjusting? Look no further than Maximus Chillers.

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Visit the Institute of Refrigeration to read industry papers.


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