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» Why are my HVAC system evaporator coils frozen?
Tuesday, 14 October 2014
An effective HVAC system relies on
electrical, mechanical and plumbing elements all operating properly and
efficiently. There are many areas where problems can develop and one of the
most common reasons for a HVAC fault is when an evaporator coil freezes up.
The initial signs of a freeze-up include a sudden drop in
performance, high indoor temperature and reduced airflow. But why do HVAC coils
freeze up? It’s due to restricted air flow meaning the coil drops below 0°C,
resulting in moisture on it to freeze. Here are some of the many reasons why
this occurs:
Defective blower
motor
The fan within an air handling unit (AHU) is commonly known
as a blower and is essential for providing airflow across the evaporator coil.
Should the blower motor not be operating correctly or is broken down
completely, the coil will freeze up. Regular motor checks and maintenance
should be carried out and motors rewound or replaced when needed.
Blocked cold-air
return grills
Obstructions to low cold-air return grills such as furniture
or equipment will significantly impede air flow. These should be moved and the
coil allowed to thaw before powering up again.
Insufficient refrigerant
A lack of refrigerant can result in low pressure within the
system which will mean the refrigerant becomes colder than the dew point. When
the coil operates below the dew point, air moisture freezes to it. Refrigerant
levels should be monitored and topped up as necessary and users should be
vigilant about leaks.
Blocked air filter
Air filters must be regularly changed or cleaned to allow
unrestricted airflow. The frequency of filter changing can vary, so check with
your installer.
Coil dirty on intake
side
If air filters in your HVAC system are neglected, then the
result may be dirty evaporator coils. Dirt builds up on evaporator coils and
eventually stops air getting to them altogether and they’ll inevitably freeze
up. So when changing filters it’s also worth checking that the coils themselves
are clean.
A properly-managed HVAC maintenance
routine can be difficult to implement when there are so many other things to
worry about. Gibbons can look after this for you with a comprehensive programme
of servicing, maintenance and repair for HVAC systems. Our engineers are
experienced in a huge range of industries and our flexibility means we’ll fit
around your schedule to minimise downtime.
For more information, call Gibbons HVAC Services
Manager Andrew Knight on 07850 204915 or email andrew.knight@gibbonsgroup.co.uk.
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