At Last !  The return of the highly sucessful  Bix 029 gas attenuator  When the boiler pressure reaches the pressure set by the control wheel the gas supply to the burner is reduced to a level set by an internal pilot valve.This keeps the burner running at a low heat. maintaining output until the boiler pressure drops. .  . We have developed two versions of this  boiler control valve .One to use with engines operateing at 5-30 PSI and the other with engines  operating at 30-80PSI.. They have  a full range of adjustment within these parameters. This has been developed in conjunction with Martin Bayliss  Engineering . The regulator is designed to be used with  a70% butane 30% propane mix ..  Comes with full fitting and operating instructions. Ideal for steam boats but can be used on a host of applications. No electronics in sight !