| udarrell 2005-07-31, 2:21 pm |
| Unless the system is sized properly, -- SEER ratings become meaningless.
(Arguments?) (These are merely my opinions -- up for discussion.)
Concerning air conditioning BTU per hour and EER ratings
Air conditioning condensing and evaporator matching systems are rated at
95°F outdoor and 80°F indoor with a 67 degrees Fahrenheit wet bulb or
around 50% relative humidity. At all other temperature and relative
humidity conditions, the BTU per hour will be different from the
specified manufacturers' ratings.
With an outdoor temperature of 95°F, indoor temperature of 80°F and a
relative humidity of 80%, the evaporator heatload output will be above
the units BTU per hour rating.
http://www.udarrell.com/air_return_...enser_split.jpg
In the event of indoor low temperature and low humidity, the Btu/hr will
drop way off.
When down sizing a system the best way to get the most BTU per hour is
to have the return air come from the ceiling area and the blower CFM at
425 ft.³ per minute in order to get an optimal heatload on the
evaporator recoil. The amount of CFM will depend on the indoor air
temperature and the amount of its relative humidity.
At normal thermostat settings of 76°F to 72°F, most air-conditioning
systems do not put enough heatload on the evaporator coil to achieve the
refrigerant boiling and heat absorption capacity of the coil. When the
evaporator is very much under heatloaded it is not achieving anywhere
near its BTU per hour or its EER rating.
Air-conditioning service technicians should always check the airflow and
approximate latent and sensible heatload on the evaporator coil "BEFORE"
adjusting the charge on the system. It is impossible to get an accurate
charge on the system unless you first have the proper heatload going
through the evaporator coil.
I wrote this post with "Dragon Naturally Speaking 8" voice recognition
software, with a few corrections.
- udarrell
--
Factors in the Correct Sizing of Residential Air Conditioning Systems -
Recommended Procedures for Proper Duct Sizing of Residential Air Conditioning Systems
http://www.udarrell.com/proper_cfm_...ng_systems.html
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