Patent ID: 8403234

Claim:
A method of providing hot, potable, domestic water in a recreational vehicle comprising: a) providing a holding tank having a predetermined volume of a liquid heating medium therein, b) providing means for heating said liquid heating medium external to said holding tank, c) providing a first pump for circulating said liquid heating medium from said holding tank through said means for heating said liquid heating medium and returning said liquid heating medium to said tank, d) providing a source for potable, domestic water, e) passing a tubular conduit through said liquid heating medium, within said holding tank, wherein said tubular conduit comprises a rectangular cross section, f) passing potable domestic water from said potable domestic water source through said tubular conduit whereby heat is transferred from said liquid heating medium, through said tubular conduit and into said potable domestic water, as it passes through said tubular conduit, g) providing at least one hydronic space heater within said recreational vehicle, h) providing an auxiliary heating assembly in communication with an external wall of said holding tank, i) passing hot combustion engine coolant through said auxiliary heating assembly to assist in heating said liquid heating medium, j) providing a second pump for circulation of said liquid heating medium from said holding tank through said hydronic space heater and back to said holding tank whereby said hydronic space heater provides heated air to said recreational vehicle, k) providing thermostatic control for sensing the temperature of said potable water passing through said conduit and disabling said second pump when said temperature is below a predetermined set point temperature.