20/10/2022
Maintenance of refrigeration and air conditioning equipment is a waste of time and an unnecessary cost Right??????
Have a quick read and let us know what you think.
We were recently called to a new customer who hasn’t had any maintenance on their cellar cooler since it was installed 3 years previously by others and we ended up agreeing unfortunately it needed replacing and here’s why...….
On arrival, we found the evaporator was a block of ice. We defrosted the system and found the evaporator thick with mould and the system was undercharged of refrigerant. We put the system on a pressure test and started to clean up the evaporator coil and whilst doing so found multiple leaks on the evaporator coil.
By not having maintenance the following has occurred;
1. Mould spoors had accumulated on the coil and enjoying the climate have multiplied over time.
2. This meant that the air flow became more and more restricted and resulted in the heat exchange surface becoming less efficient as the energy cannot transfer from the refrigerant to the coil and then to the passing air. Note the mould growth on the ceiling above the evaporator. As well as the mechanical implications, there is a health and safety consideration as well.
3. A less efficient heat exchanger does three things; First means that the system runs longer than necessary costing more money; Second, the coil becomes colder and wetter, and third, the refrigerant was going back to the compressor as a liquid causing excessive wear and tear.
4. Here we are concerned primarily with the wet evaporator coil as this is really what has ended up claiming the life of this system and here’s how;
a. As the heat exchanger becomes cold the materials come under stress and contract a little, as they then become warm the “relax” and expand. This constant expansion and contraction cause friction and weakness. When an electric defrost is present, a blocked and dirty coil will also impact the ability of the heat to transfer through the coil warming parts of the coil up more and at a different rate than others causing additional stress and longer defrost times which is like having a kettle permanently boiling for long periods of time unnecessarily
b. As the evaporator coil is running wet and for longer, there is a much reduced off cycle which would normally help the evaporator to dry. The moisture is unable to run off because the mould has absorbed it and thus trapping it to the metal surfaces. I’m no chemist but basically this causes corrosion as the water reacts with the iron in the steel and forms rust which eats away at the material further weakening it.
c. Galvanic corrosion is present due to an electrolysis process that occurs which is caused by two dissimilar metals reacting in the presence of an electrolyte. In this case we have copper, aluminium and steel with water acting as an all-be-it weak electrolyte.
d. Finally, the drain and drain pan is holding so much debris that it is holding the water rather than letting it fully drain. This is then recycling the mould spoors and bacteria into the air, as well as maintain a highly humid environment and even allowing parts of the coil to sit in the water itself exacerbating the corrosive processes detailed above.
Poor or inadequate standard of maintenance can be just as bad as no maintenance at all....
We have found that maintenance has a bad reputation because people say that it doesn’t protect them from future issues and is a waste of money. If we isolate this particular issue and consider that it may have been maintained, but to a poor standard, here is what it may look like:
1. The engineer takes a brush to the back of the coil and brushes the surface dirt away. This clears the surface and inadvertently pushes rubbish further into the coil which starts to block the centre.
2. The engineer sprays a coil cleaner onto the surface, probably from the back which is a chemical and will react with the dirt, but also the coil. Has the chemical been mixed at the correct ratio? Not enough and it doesn’t do the job it was designed to do, and too much and it will react aggressively to the coil. Not putting enough cleaner on is again a waste of time, not leaving it for the correct amount of time is also a problem, and then not rinsing it off sufficiently will leave it reacting for a long time to come, again breaking that coil down.
3. The next question is the chances of the evaporator coil centre being choked is high, and the chance of chemical first breaking the dirt down in a short period of time low, and second the chance of effectively rinsing the chemical out of the coil also low.
4. Not allowing enough time to do the maintenance means;
a. That the engineer will only attack the coil from one site rather than two
b. That the dirt will not be fully broken down
c. That the mixture will likely be incorrect
d. That the coil will be inadequately rinsed
e. The drain will not be vacuumed and sterilised
f. That the Superheat will not be checked and evaporator efficiency optimised
g. Defrosts won’t be fully checked and operate efficiently due to dirt which is a huge electrical cost.
Conclusion is that poor maintenance is as bad as not having any maintenance.
Good maintenance however is a completely different ball game and here’s why;
1. You are managing your assets proactively meaning that you are more in control, better informed and less likely to be caught out
2. Your assets will run more efficiently and effectively meaning that it costs you less in energy bills, less in wear and tear and achieves the results you originally invested for
3. Efficient and effective operation with reduced wear and tear
a. Saves time and money in the long and short term
b. Reduces downtime and parts failure with more reliability and predictability
c. Extends the useful life or the asset by upwards of 100% depending on environmental and design factors.
d. Is environmentally prudent meaning less waste produced, less energy used, reduced carbon footprint.
If you've read down this far then firstly well done!!!
But secondly it shows you may be interested in maintenance on refrigeration and air conditioning systems and hopefully this has been insightful enough for you to look at your equipment and see if your current regime is fit for purpose.
If you feel it isn't and you think we can help then please feel free to contact me.
