Why Filter Service is so Important
Regular filter maintenance is crucial to keeping HVAC ductwork clean. Dirt accumulation in ductwork plus relative humidity reaching dew point, at which time condensation occurs, causes bacteria and mould to grow.
This is especially the case in HVAC systems that have acoustical duct liners. They're frequently used in air-handler fan housings and supply ducts to reduce sound transmission and provide thermal insulation.
The increased resistance caused by the dirty filters reduces air flow to the unit, negatively impacting on the units heating/cooling and energy efficiency.
Dirt that has migrated beyond the filters is deposited on and blocks the coil that the filter should be protecting. All inspections and corrective actions should be documented for IQP purposes.
Why Coil Cleaning is so important
Condenser coils are exposed to unfiltered outdoor air - suffering from degration due to dirt. The performance penalty of a dirty condenser makes this task one of the most cost-effective4 energy-efficiency practices available for rooftop unit maintenance. A dirty coil reduces the cooling ability of the air blowing across the condenser coils.
If the condensing temperature is raised by 10 degrees celsius, cooling capacity will be cut by 7 percent abd increase power consumption by 10%, compressor efficiency is reduced by 16%. Such performance degration in a 10-ton unit operating 9.0 EER for 2000 hrs/p/a at 16 cents per kW/hr wastes about NZ$500 per year in operating costs.