23 September 2011

NOISE LEVEL IN RELATION TO ENERGY PERFORMANCE OF AIRTO- AIR HEAT PUMPS


With increased use of air source heat pumps, a possible barrier for further market
growth and customer acceptance is their noise level. The disturbance is both an issue for the
owner of the heat pump and the neighbors since both the indoor and the outdoor units
radiate sound. The purpose of this study is to create an understanding of the noise
generation of air-to-air heat pumps and relate this to their energy performance. This
knowledge is then to be used in continued work when describing the total disturbance of a
heat pump.
Two heat pumps, both of inverter type and with different noise performance were selected for
measurements. Energy performance, in the form of Coefficient of Performance (COP), was
evaluated at different operating conditions. Measurements of the sound power level were
performed on both the outdoor and the indoor units. Results show that the sound level from
the indoor units is independent of the outdoor conditions. The noise from the outdoor units
varies with different climates and the variation is particularly large at part load conditions.