The Concentric Pipe Heat Excanger

Two Heat Transfer Modes

Convection Q˙=h A ΔT (BTU/hr)

Convection requires fluid flow in the heat exchanger which cycles on and off with the thermostat. This is an issue because, even for extreme temperatures, convection is active less than half the day and generally one sixth to one quarter of the day (4 to 6 hours).

Conduction Q˙=k A(ΔT/Δr) (BTU/hr)

Conduction stops when the differential temperature across the pipe becomes zero. The Concentric Pipe allows 12 times more thermal storage, extending conduction.

Thermal conductivity of HDPE pipe is one quarter of other materials in the system, limiting the system thermal conduction rate.