  A double fountain pressure model is used to analyze the recent measurements
of Yu and Luo (arXiv2211.02236v4) of superfluid $^4$He flow between two
chambers held at different temperatures via two superleaks and an intervening
third chamber that spontaneously achieves a temperature higher than both fixed
temperatures. The physical origin of the increased temperature in the
intervening chamber is attributed to the balance between the rate of mechanical
energy deposited by superfluid transport and the rate of convection back to the
lower temperature chambers. An equation is given for the pressure of the third
chamber, the measurement of which would confirm or refute the theory.
