See those three unions (screw on collars) on each of the three pipes leading to the multi port valve? When I buy a new multi-port valve for the purposes of connecting it to the plumbing do I need to just buy the plumbing parts from the valve to the union? It appears with my existing valve that the pipes are glued on to the openings of the multi port valve - is that the way I am supposed to connect the pipes to the valve or should I join the pipes with some kind of fitting that would just allow me to screw the pipes into the valve? To me it makes sense to glue the pipes into the valve if they can be disconnected at the screw on collars in case in the future I need to change out the sand before needing to replace the valve again. In researching replacement valves I have learned that this collar cracking issue is common due to the thin plastic used on the valves so I imagine I may have to replace the valve yet again before it comes time to change out the sand.
I know this is a dumb question but I want to make sure the screw on unions are just holding the existing pipe with friction force as it does not appear to be glued on and I don't want to experiment when I don't have the parts ready in case I need to fix it immediately. Would I need to buy new screw on unions? I want to make sure I am by all of the parts ahead of time so that I minimize the amount of time the filter is off-line. You can see from the picture that the valve is pretty old and leaking at the collar. It is actually cracked at the collar where the Valve sits on top of the filter.ImageUploadedByTapatalk1414192056.803550.jpg