Full Description

The performance of conventional split-system residential air conditioners is highly dependent on adequate air flow across the evaporator coil. Sufficient air flow is necessary to achieve a proper balance between sensible and latent cooling capacity. Typical target air flow rates are approximately 350 to 450 cfm per ton (581 to 747 L/s per kW) of cooling capacity. The air flow across the coil in 27 installations in Florida were measured. Both flow hood and strip heat resistance methods were used to measure air flow with an established protocol. The measured installations ranged in capacity from 2 to 4 tons (7 to 14 kW). Measured air flows ranged from 130 to 510 cfm/ton (538 L/s per kW). Reasons for inadequate flows included undersized return ducts and grilles, improper fan speed settings, and fouled filters and cooling coils. In addition, high distribution system static pressures were caused by long, circuitous runs and pinched or constructed ducts. Recommendations are made to improve current practice.

Units: Dual

KEYWORDS: year 1997, Evaporators, cooling coils, performance, measuring, unit air conditioners, air conditioning, domestic, air flow rate, USA, testing, optimising, designing, maintenance, air filters, ducts, size, pressure drop, undersizing, oversizing

Citation: Symposium, ASHRAE Transactions, Vol.103, Part 2, Boston 1997