Abstract: A van-mounted or mountable cleaning system as disclosed includes a water heater having a burner therein to heat the water and a flue outlet to release combustion gases therefrom. A motor driven vacuum blower has an air input port and an output port for blower exhaust, both the water heater and the vacuum blower being mounted or mountable in an interior portion of the van body. A flue gas duct is connected to said flue outlet and extends downwardly toward lower extremities of the van body and then, in use, leads outwardly of the van body. An exhaust conduit enters into said flue gas duct in such manner as to create a Venturi effect therewith tending to draw combustion gases away from said burner along said downwardly extending flue gas duct and thence outwardly of a lower portion of the van body in which the system is installed.