HVAC System Evaluations

Heating, Ventilating & Air Conditioning (HVAC) systems, in general, are designed to control interior temperature; however, they also have a major impact on the ability to control moisture in or under a structure.  While properly sized equipment may offer limited interior humidity control, improperly sized equipment may allow humidity to go unchecked, resulting in uncomfortable interior conditions and fungal activity.  HVAC systems and their associated ductwork also directly affect conditions within a crawl space or under an elevated house, where excessive moisture can invite termites and lead to fungal activity and structural concerns.  Owners are typically unaware that the interior temperature they maintain also affects conditions below the living space and that lower interior temperatures require additional considerations.

Aside from pest and structural concerns, simply put, most homes and small businesses in the Lowcountry are not capable of maintaining acceptable indoor air quality*.  Many have moisture-related problems unique to the region and/or have deficient air conditioning systems; most, however, were simply designed without regard to indoor air quality and do not incorporate an HVAC System capable of providing the fresh air ventilation, filtration and humidity control necessary for sensitive occupants.

If excessive moisture has been discovered in or under your home or business; or if you suffer from asthma or sensitivities to allergens or other irritants, Air Plus can help by providing you with a professional HVAC evaluation.  In addition to adequate temperature control, the system will be evaluated for humidity control, proper filtration and fresh air ventilation.  If deficiencies are discovered, Air Plus will make recommendations to adequately address those deficiencies and facilitate project implementation. 

NEW CONSTRUCTION

The best time to address moisture and indoor air problems is before they happen.  A properly sized mechanical system may satisfy your thermostat, but since moisture is only removed as a secondary function of standard air conditioning, you may not feel comfortable due to elevated humidity or humidity swings; and worse, elevated humidity may result in interior mold and allow dust mites to flourish.  A properly designed mechanical system will not only satisfy the thermostat, it will also provide effective humidity control, effective filtration and provide fresh air ventilation for improved indoor air quality.  Add properly designed substructure (crawl space) moisture control and issues such as sweating ducts, mold, cupping floors and substructure decay will be eliminated (and termites hate a dry crawl space).  

Residential structures are complex and the environment we live in demands that all of these issues be addressed with new construction.  Unfortunately, building codes do not effectively address (if at all) these issues and, without input from a design professional, mechanical contractors have historically only addressed the "temperature" part of indoor air quality.  Air Plus can help by providing you or your contractor with a professional HVAC load calculation and recommendations (scope of work) for acceptable indoor air quality and interior & substructure moisture control. 

 

* ASHRAE (The American Society of Heating, Refrigerating, and Air-Conditioning Engineers) defines acceptable indoor air quality as: air toward which a substantial majority of occupants express no dissatisfaction with respect to odor and sensory irritation and in which there are not likely to be contaminants at concentrations that are known to pose a health risk.

PICTURES FROM THE FIELD

Location: Merion Place, Charleston National, Mt. Pleasant, SC

The owners of this 7-year old Charleston National home complained of a "mold-like" odor in the Kitchen.  Observations in the Kitchen and Bathroom revealed a configuration prone to experience moisture problems. The supply ducts in these two locations (located in the crawl space) terminated at the subfloor and discharged air into the "toe space" below the cabinets, which acts as a plenum. The air is then discharged into the room via a vertically mounted air register. The configuration allows for cold supply air (55-60 degrees) to be trapped under the cabinets and blow directly onto the adjacent floor, thereby cooling the subfloor to below the dew point temperature of the air located in the crawl space, resulting in the formation of condensation and subsequent fungal activity.

Location: Jamaica Drive, Byrnes Downs, Charleston, SC

The piece of furniture looks harmless enough, but the arrangement is trapping cold air against the floor and causing condensation to form on the subfooring.  The wood is saturated and well above the 28% wood moistrure content necessary to support active wood destroying fungus.  Fortunately, the situation was caught before major structural damage occurred. 

 

Location: Pignatelli Crescent, Dunes West, Mt. Pleasant, SC

It doesn't get much worse than this.  The air handling unit located in the crawl space of this home in Dunes West was literally sitting in the mud.  The floor insulation was falling down and the floor system was beginning to rot.  Mold-laden air from this unsanitary crawl space was being readily drawn into the air conditioning system and distributed throughout the home. 

 

Location: Burningtree Road, Country Club II, James Island, SC

In addition to poor thermal performance and reduced energy efficiency, improperly maintained or damaged ductwork or duct insulation can be detrimental to your crawl space.  With the insulation falling off, the floor system above this section of ductwork is being cooled to below the dew point temperature and condensation is forming on the joists and floor insulation.  The longer this goes undiscovered and/or unaddressed, the more serious the problem will get.  There is already substantial fungal activity and structural damage will soon follow.