Chiller Service & Maintenance

Tick Sheet

Tick Sheet  

Our technician will carry out a detailed tick sheet and inspection. If any issues are identified, a complete controls, component and refrigerant diagnosis will be carried out

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Pressures

Gas Charge 

System pressures & temperatures will be taken to work out Superheat and Subcooling

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Break Down

Faults

Chiller struggling to achieve set point? Showing error messages? Maximus Chillers can help. Our engineers carry an extensive range of commonly used parts. Our fast supply chain offers next day delivery of specialist parts and materials

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Save Money
Save Money

Planned Preventative Maintenance

Our visits will save you money. With regular maintenance our engineers will get your chiller running better than when it came out of the factory!

Live Electrical Testing

We are trained and certificated in live electrical testing end electrical fault finding

Multi-meter
Multi-meter

Gas Charge

Superheat
In a fridge system it is very important to know the superheat value of the low side of the system. Too much superheat is a sign that it is short of gas and not enough is a sign of a fouled evaporator. During the maintenance we work out this value as part of giving your chiller a full health check

Subcooling
This is the value of the high side of the system. Not enough subcooling is a sign of a blocked condenser. Too much is a sign of non-condensables in the system giving false readings

Faults

A lot of faults can be rectified with the stock of parts and materials that the engineer carries in his car. While we are on the maintenance visit we don’t even put this through the books it is all part of the service. As far as we are concerned you are paying for us to be on site and we will do anything to improve the condition of your machine. This is just part of the no-nonsense, non-political way we deal with the customer- you! If we can keep your costs down and keep you happy- that makes us happy!

Tick Sheet

Check program settings
Check program timers
Check sensor and transducer calibration
Check set point
Check expansion valve (steps/ %)
Check refrigerant leak detection system
Check emergency stop
Check UPS
Check evaporator heater (amps)
Check overload settings (amps)
Check compressor contactor contacts
Check and tighten wiring
Check and tighten motor connectors
HP cut out
LP cut out
Check fan HP controller
Check flow switch
Leak test
Δ P (kpa)                    Evaporator in
                                   Evaporator out
Check pressurisation unit
Check glycol %
Pumps: water/ glycol/ refrigerant
Clean water strainers
Check water levels in evaporative condensers
Check sight glass(es)
Check oil level
Check crankcase heaters
Check oil separator/ oil pot heaters
Drain oil from evaporator/ sumps/ oil pot
Manually operate oil return valve
Examine oil: analysis required?
Unwanted ice: coils/ trays
Pump in oil
Check shaft oil leaks
Grease motor bearings
Fans: condenser/ evaporator/ door
Filter change: oil/ air/ refrigerant/ door
Check condenser(s) evaporator(s) condition

 

Ambient
% load
Suction pressure
Suction saturation temperature
Wet suction temperature
Dry suction temperature
Superheat
Liquid pressure
Liquid saturation temperature
Liquid condenser temperature
Liquid LPR temperature
Subcooling
Discharge pressure
Discharge temperature
Oil pressure after filter
Oil pressure after pump
Oil differential
Oil separator temperature
Oil compressor temperature
Oil pot temperature
Δ T                   Chilled water in
                        Chilled water out
Condenser water in
Condenser water out
Air-cooling evaporator(s) on
Air-cooling evaporator(s) off
Compressor load/ unload
Compressor run amps
Incoming volts
Motor side volts
Check corrosion/ vapour seal: paint required?
Check drip pan/ defrost heaters
Check insulation
Check vibration isolators
Check undue noise
Check relief valve date

Evaporator Freeze-Up
The worst thing that can go wrong with a chiller is an evaporator freeze-up. It can happen for various reasons:

Chilled Water Pump Goes Off
The lead pump is switched to the lag during maintenance. This is to test the BMS switch-over and the stand-by pump. If there is only one pump or the BMS/ stand-by pump has failed- freeze-up!

Not Enough Glycol
A refractometer is used during maintenance to check the glycol level. Over time as the water system make-up (pressurisation unit) adds water to the system- the glycol gets weaker. It starts slushing and freeze-up!

Blocked Strainer or Pressurisation Unit Failure
Both of these faults cause a reduction in flow. Therefore, the water stays in the evaporator longer and has more time to cool down- freeze-up! The Evaporator pressure drop (Delta P) and the pressurisation unit’s pressure are checked during maintenance

So how does the chiller protect itself?
Flow Switch
This is a paddle in the water system that trips the chiller when the flow goes off. They are prone to seizing, so they are checked during maintenance

Pressure Differential Switch
Like the flow switch this detects loss of flow. If there is a low difference in pressure across the evaporator it trips the chiller

Water In and Out Sensors
On a chiller used for above zero applications the trip out temperature is usually 2° An issue with this type of safety device is when the pump goes off, the sensor may be reading 12° whilst in the evaporator, it is zero

What happens when the safeties fail?
The compressor carries on running. The evaporator turns into a solid block of ice. Ice has a larger size than water so as it expands, it buckles then bursts the evaporator. The compressor still carries on running. Refrigerant leaks into the water system until the pressure in the fridge system and the water system equalise; then water is sucked into the fridge system. It gets sucked into the compressor and round to the condenser. Compressors cannot compress a liquid so a compressor smash-up occurs

How do we pick up the pieces?
The compressor or compressors need to be re-built. The evaporator needs to have the burst tubes identified then plugged. The system needs to be dehydrated using a vacuum pump which takes several months. On a smaller chiller, the labour costs outweigh a replacement- so the chiller is ruined

What can be done to prevent this?
Regular maintenance is essential to stop this happening and to prevent other small problems becoming big ones. If however, your chiller does need repair, at Maximus Chillers will get your chiller working better than when it came out of the factory!

Plate Heat Exchanger Evaporator
Plate Heat Exchanger Evaporator

Countdown for R404a/ R422d Service Ban Above 40 Tonnes of CO2 Equivalent

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