Apparatus controlling a plurality of fuels of different heat contents to a fluid heater burner including valves for selectively connecting the fuels to the burner and pressure responsive fuel flow regulators responding to the combined fuel/air pressure at the fuel burner to provide {HEAD ~ a given level} of output for {TAIL ~ the boiler} 
for
Apparatus controlling a plurality of fuels of different heat contents to a fluid heater burner including valves for selectively connecting the fuels to the burner and pressure responsive fuel flow regulators responding to the combined fuel / air pressure at the fuel burner to provide { HEAD ~ a given level } of output for { TAIL ~ the boiler }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL