Hey I am just finishing my level 2 working on central heating installs at the moment. Most if not all boilers have a clamp that secures the turret flue elbow to the boiler. But not all have a clamp that secures the turret flue elbow to the flue, iv noticed the ideal boilers we sometimes fit don't. So it looks like its the sand and cement around the flue hole that is securing the flue to the turret elbow after its been pushed home. Do manufactures class that as enough if they provide no clamp?