Internal condenser for heat pump water heater

Abstract

An internal double wall condenser for a tank-type heat pump water heater. The condenser includes inlet and outlet sections designed for low heat transfer and a coil section designed for high heat transfer. The condenser includes first and second inner tubes that conduct refrigerant, and an outer tube surrounding the inner tubes. The outer tube has a circular cross-section in the inlet and outlet sections and a barbell cross-section in the coil section. The barbell cross-section includes first and second conduits that contain and are in heat transfer contact with the respective first and second inner tubes, and a connecting portion that interconnects the first and second conduits and increases the heat transfer surface. The barbell cross-section is made by deforming the outer condenser tube such that opposite walls are brought together between the two inner tubes.

Dependencies are inferred from the claim text.