Climate change concerns are driving improvements to the energy efficiency of buildings. Concerns over climate change have sparked many strategies including improving the energy efficiency of buildings. CoilPod director, Richard Fennelly, explains how a routine refrigeration maintenance task, which is almost universally ignored, can deliver big energy savings.
At the recent COP22 meeting in Morocco, the director general of the International Institute of Refrigeration, Didier Coulomb, said the power consumption of refrigerated facilities needs to be reduced in a drastic way.
He went on to say that: “The replacement of today’s technologies using high GWP refrigerants needs to go hand in hand with a true effort of increasing the energy efficiency of facilities and systems more generally”.
We nominate what follows as something that will definitely “increase the energy efficiency of systems more generally” but only if all the refrigeration stakeholders make a “true effort” to carry it out as widely as possible.
Cooling appliances (“coolers”), many of which are within buildings of all types, have condenser coils that are responsible for throwing off to the atmosphere the heat that has been extracted from the chamber holding the items intended to be refrigerated or frozen.
To facilitate that heat exchange process, these coils, when contained within the appliance’s cabinet, have airflow directed through their structure by a fan in the condensing unit. All matter of dust and debris are also drawn in with that air causing clogging of the coils over time.
Foster Refrigerator (UK) has recently stated that an airflow reduction of about 95% can be expected over a one year period of operation. We have seen no other data on this point which is generally unappreciated by the unit’s owner. Experts recommend frequent coil cleaning to insure good airflow - often at periods of every three to four months as a minimum, and even more frequently in extremely dusty or dirty environments.
Clogged coils cannot effectively throw off heat since the dust/debris forms an undesired insulation layer. The refrigerant flowing through the unit gets too hot (resulting in high pressures) and starts damaging other components.
The system also draws higher amperage. Run times of the compressor increase, the refrigerant degrades restricting its flow, and so forth. A number of undesired things will happen as a result:
1. Energy waste: recently third party data, which is available from us, has shown that the amount of energy needed to operate the appliance can increase by as much as 90% to 100% ---- at the relatively low electric rate of $US 0.11/KwH this amounted to a yearly per unit increase ranging from $US220 to $US625, with the average being about $US430.
Converting these numbers to the electric rates in Australia, which are about twice the US rate, and applying the appropriate currency conversion, one gets a yearly/per unit electric energy waste of from about $A610 to $A1,725, with the average at $A1,190. Owners are completely oblivious that their clogged coolers might be costing them this much.
Its why keeping coils clean under a preventative maintenance schedule is so important. One refrigeration expert has stated that 80% of owners of these refrigeration units never do coil cleaning and that the remaining 20% do it too infrequently (for example, annually). My experience supports this assessment.
2. Malfunction of the Unit: If the unit runs with clogged coils, the owner may face an emergency service call which can lead to a very expensive service call involving proper removal of the refrigerant gas and tear down of the system. It can lead to four to six hours of labour costing possibly $A1,400 to $A1,900, based on US data that has been currency converted. In extreme cases, repair might not be possible or recommended, and the unit will need to be replaced.
The same expert mentioned above stated that quarterly coil cleanings may virtually eliminate unscheduled service calls that generate a major bill.
3. Loss of Valuable Product Inventory: If the unit begins to malfunction, it may not be able to maintain the target temperature within the enclosure being cooled leading to refrigerated items being compromised.
4. Shortening of the Life of the Unit: Malfunction of the appliance can also lead to a shortening of the useful life of the unit. No hard data appears to exist on this point.
5. Safety Issues for Hydrocarbon Refrigerant Units: There is a current and powerful movement to replace hydrofluorocarbon refrigerants, which are bad for the environment, with “natural” refrigerants that are much more benign. One class of such refrigerant are the hydrocarbons, such as propane (“R-290”).
This type of refrigerant is highly flammable and can be problematic in indoor locations unless certain safely measures are followed. One refrigeration safety expert has recently advised that R-290 refrigerant units need to have their condenser coils in a clean condition along with constantly running fans in the condenser coil area to promote good ventilation.
He admitted to us that keeping the fans running will exacerbate the coil fouling problem, making a disciplined coil cleaning program all the more important. So How Are the Condenser Coils To be Cleaned?
Mere surface brushing and vacuuming of the condenser coil structure will remove the surface matting of dust/debris but doesn’t get at the clogging occurring within the interior of that structure and is not recommended if one really wants to insure a proper cleaning for the coil unit.
Specialized coil cleaning brushes are available that allow for extraction and removal by vacuuming of the deeply embedded dust/debris. Use of these implements greatly increases the time needed to get the cleaning job done and is not attractive for that reason.
For decades, knowledgeable technicians, usually only on an emergency service call when one unit is being serviced, have resorted to the use of compressed air to very quickly blow out clogged condenser coils. However, doing this in indoor locations, requires effective capture of the blown off debris to insure that no collateral contamination is caused.
Until recently, the technicians using compressed air coil cleaning have resorted to the use of a damp fabric or large garbage bag to try to catch the debris blown out of the coils. These primitive items both have serious deficiencies.
The damp fabric, which is applied to the side of the coil unit opposite the input of the compressed air, in many cases might not stay in place during the cleaning causing undesired collateral pollution requiring further clean up. If it did remain in place, the technician had to contend with a thoroughly polluted, damp article requiring cleanup or disposal.
The cleaning of a large number of units in a preventative maintenance scenario is not well served with the use of a damp fabric. The use of a large garbage bag to attempt to catch the blown-off debris commonly may require two technicians, one to hold the bag, the other to do the blowing.
This method also can allow some of the blown off debris to miss the open end of the bag being held. While a single operator can use this method, the bag needed to be taped or affixed to the coil structure which undesirably slows down the cleaning operation.
Only within the last five years or so has attention turned to more effective, engineered dust containment products that the technician may employ when using compressed air to clean clogged condenser coils. The COILPOD dust containment bag (or hood) is a leading example of this type of technology.
It can be first fitted over accessible, compatibly sized coils in need of cleaning, and the drawstring at its mouth can be tightened to seal the dirty coils within the bag. The two ports in the transparent front of the bag accommodate a source of compressed air and vacuum, respectively.
At this point the compressed air and vacuum are turn on and the blown off debris stays trapped inside the bag until it can be vacuumed out. Pollution of the surrounding area is precluded to a more substantial degree than the primitive wet fabric or garbage bag capture methods.
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