this particular environment it is done merely for purposes of illustration and it is to be understood that the present invention may be used in other environments in conjunction with fuels other than gas and with fuel consumptive apparatuses other than gas furnaces for instance the teachings of the present invention are equally applicable to a hot water supply which is provided to multiple locations from a single hot water heater the gas supply 12 which may be from a public utility or a common storage tank is fed to a plurality of gas meters 14 16 18 and 20 through a pipe or conduit 21 pipe 21 as well as other pipes hereinafter mentioned is shown and described as comprising a plurality of different length sections and a plurality of couplings or fittings however this is merely meant to be illustrative and any piping configuration or other means for permitting the communication of the elements of the present invention and specifically for permitting the inputs of the meters 14 16 18 and 20 to be in direct communication with the gas supply 12 can be employed by one skilled in the art within the scope of the invention the outputs of the gas meters 14 16 18 and.