1. Field of the Invention
The present invention relates generally to air source heat pumps and more specifically it relates to a heat pump defrost system for efficiently defrosting an outdoor coil while simultaneously operating the heat pump in a normal heating manner.
2. Description of the Related Art
Any discussion of the related art throughout the specification should in no way be considered as an admission that such related art is widely known or forms part of common general knowledge in the field.
Air source heat pumps are commonly utilized for heating and cooling interior spaces of homes because of their high efficiency that lead to cost savings over time. The heat pumps transfer energy in the form of heat from a cooler location to a warmer location. During cold temperature regions, in which the outdoor ambient air temperature is less than approximately 32 degrees Fahrenheit, it is common for the outdoor coils of the heat pump to accumulate frost and ice, thus blocking air flow and preventing the heat pump from operating effectively.
Present day air source heat pumps have a defrost cycle to clear frost from the outdoor coil when the temperature is below freezing. The defrost cycle takes heat from the indoor area to generate enough heat to defrost the outdoor coil. This usually happens at predetermined intervals and lasts for a predetermined amount of time. When the defrost starts the defrost control brings on the back-up heat source to heat the house, which may be comprised of an electric heat source or other.
The back-up heat source, however, is often times less efficient than the heat pump. Thus, the heat pump is operating at a high efficiency to defrost the outdoor coils and the primary area of interest, which is the interior space of the home, is being heated with a less efficient heat source, such as an electric heater. This can add to costs associated with heating a home, as well as an overall uncomfortable feeling of the house becoming slightly cooler while waiting for the electric heat source to take over and heat the house while the heat pump is in the defrosting cycle. Because of the inherent problems with the related art, there is a need for a new and improved heat pump defrost system for efficiently defrosting an outdoor coil while simultaneously operating the heat pump in a normal heating manner.