there can be an airlock happen in the heater, I think it has to do with which fittings on the engine go to 'top' or 'bottom' of the heater, makes a difference on the TF heaters
"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir "When we tug a single thing on an old truck, we find it falls off" ~ me Some TF series details & TF heater pics
