Wondering about how energy efficient your new boiler will really be? Soda crystals - chuck down a good half bag then following with kettles worth of boiling water you may need to repeat or times if it's really bad the washing soda is cheap as chips too -. We are fully trained to handle any job you’ve got- put the duct tape down and call us! Registered in england & wales company no vat no . Installation, operating and service instructions.