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
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 equalize; 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 replaced. 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.
Chiller Tick Sheet
The Following are checked on our detailed Tick Sheet
Check crank case heaters
Check oil level
Check flow switch
Check emergency stop
Check sensor and transducer calibration
Check program settings
Check set point
Check HP cut out
Check LP cut out
Check low temperature water cut out
Check overload settings
Check residual current device
Check fan HP controller
Check compressor contactor contacts
Check evaporator heater
Check and tighten wiring
Check and tighten motor connectors
Check sight glass: wet, medium or dry
Check evaporator Δ P (difference in pressure)
Check relief valve date
Check condenser condition
Check vibration isolators
Is an oil analysis required?
Glycol level %
% of load
Check evaporator Δ T (difference in temperature)
Do the compressors load and unload?
Compressor run amps
Motor side volts
Service history in the log book
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 the fridge system 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
This is a 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
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!
Schedule a Site Visit Today!