At Last !  The return of the highly sucessful  Bix 029 gas attenuator  . Aprox size  60mm x 50mm including nuts & tails, 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 .  ..  Comes with full fitting and operating instructions. Ideal for steam boats but can be used on a host of applications. No electronics in sight !