Plumbing to the multiport valve of filter

[tomsop]

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.

 

[JasonLion]

There are several different ways to approach this situation. The most straightforward is to replace the plumbing from the valve to the unions, including the half of the union that is glued to the valve side plumbing. To do this you need to find exact matches to your existing unions.

Pipe is normally glued directly to the valve. You could glue in a fitting with a screwed in connection, but that presents a number of challenges. Unions, like you have now, are a much better solution.

Unions are screwed together by the outer collar. Only fiction prevents the collar from unscrewing.

 

[tomsop]

Thank you for that. I never shopped for these before so I hope these type of unions are easy to find. I will glue on half of the new union and then screw on to the existing pipes that have the other half of the union on their end if I follow correctly.

 

[zea3]

These unions look like the type that are available at Home Depot or Lowes. They come in both threaded and slip so make sure you get the slip unions if you plan to glue the plumbing together.

 

[gtemkin]

...... I will glue on half of the new union and then screw on to the existing pipes that have the other half of the union on their end if I follow correctly.

Be aware that union manufacturers do not always share the same internal design. A half union from one manufacturer may not connect to the opposite half of another manufacturers union. You must test this by pre-assembling them before glueing to be sure they're interchangeable. Save your receipt in case they don't work and you need to return them. They are some of the priciest plumbing bits in the PVC aisle.