Air conditioning Refrigerant Freon leaks

In the last several posts we have been discussing different consequences of not changing air filters or not having them at all.  Some of the more severe consequences are frozen evaporator coils (inside/ air handler), which we have also discussed.  When ice expands so rapidly sometimes things move and or shift. That can create small cracks in the coil which eventually leads to bigger cracks.  Some systems have high and low pressure switches built into the condencers that would stop its operation if system is running outside of designed refrigerant parameters.  Some do not.  Those condensers tend to have burnt out compressors.  At that point that is a huge expense if wether parts are under warraty or not.  So again, please change your filters and make sure to do a diagnostic/ system check up at begining of each cooling season.  A skilled technician (ours) can spot issues before they occur and recommend best possible solution.

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Leaking evaporaor coil. Not repairable

No filter in central air system

Last week I wrote an article about having a really dirty air filter and why it is a important to change them regularly.  In that article we discussed that dirty filters will restrict airflow in the air handler, which can cause serious malfunction in the system.  Now, lets talk about the repercussions of removing the air filter entirely and forgetting to put one back in .  The same effect as a dirty filter is recreated inside the evaporator coil. Dust gets lodged in between the coil fins, which forms into a giant patch and restricts air flow.  Side effects may include coil freezing and compressor burnout.  At the least it will require the coil to have specialized cleaning which may be expensive and in extreme situations the coil must be removed entirely for propper cleaning.  However, this can all be avoided if the air filter is replaced regularly.

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Effects of not having an air filter in central air

Air conditioning repair Nanuet NY

Evaporator coil dirt blockage due to lack of filter

Importance of changing air filters

There seems to be a lot question and misunderstanding as to how often to chance air filters in central air system (hot air furnace heat).  Hopefully reading this will clarify some questions. First, allow us to explain the basics of mechanics of forced air system.  Each system contains a motor (blower), which is designed to spin at a designated rpm, which must generate a certain amount of air movement. Besides the blower there is also an evaporator coil.  The coil  contains refrigerant that boils of at subfreezing temperatures and requires a certain amount of airflow to keep it warm.  A filter is designed to allow air to flow through it while catching dust and dirt that is suspended in air.  This is a benefit to breathing air as it is cleaner and protects the evaporator from dirt.  Filters come in different levels of filtration efficiency and the higher the efficiency the less airflow they allow through them from the start.  Additionally dirt and dust accumulation create a form a layer around the filter creating an airflow restriction.  Sometimes this airflow restriction creates a bottle-necking in airflow and puts significant strain on the motor as well as an insufficient heat for the coil, which may result in motor failure and or coil freezing (picture bellow). This must be avoided at all costs.

So as to original question of how often to change the answer is not so simple as there are many variables including efficiency of filter (the more efficient the more frequently it must be changed) and other dust factors.  Carpeting contains a lot of dust as well as heavy foot traffic and pets generate more dust.  So the more dust in house the more often a filter must be changed.   The solution is quite simple, install new filter and check after two weeks. When the system turns on and the filter gets sucked in and concave (a sure sign of air pressure change), or filter shows a layer of dust or discoloration then its time to change.  If not wait a week and check again. Keep doing so until you notice any signs of a blocked filter. Some houses can be on one filter for 3 months and some houses only 2-3 weeks. Its is up to the homeowner to determine how often. Please do not rely only on the serviceman to change your filters once a season as it is not enough for any household. Picture below shows a frozen coil, one of many we encounter throughout the summer season.

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Frozen evaporator coil