Can someone explain how pvc unions help future modifications?

[XLIII]

There are many threads identifying the benefits of union placements where you might have to disassemble later. However, I think I am missing a key concept.

For slip unions, it seems you are supposed to cement them similar to elbows. Doesn't this make a permanent connection? How is it advantageous then to add a union preemptively?

I see them as only useful if you want to fix a pipe you cut where you can then combine multiple pieces, but no purpose on initial build.

 

[exnisstech]

The union allows disassembly without having to cut the pipes. Kind of like having a nut and bolt vs a rivet or weld

 

[ShakeyGizzard]

The unions allow you to remove sections of the overflow/return pipes, you wont have to remove the whole piece. This will be needed if you add to the pipes, make equipment changes, and in some cases cleaning

 

[Cycleguy0623]

For me the unions make sump cleaning and pump removal much easier. They allow me to do maintenance much easier overall in a fairly tight sump. With extra unions of the same manufacture laying around you can also redo parts of the plumbing much easier than having to cut up pipe as often.

 

[Paul B]

You don't have to use a union if you don't want. PVC is very easy so if you want to change something just cut the pipe and either put it back together with a coupling, for about 50 cents or a union for $7.00. It doesn't matter, you can just keep cutting the pipe as much as you want.

 

[XLIII]

The union allows disassembly without having to cut the pipes. Kind of like having a nut and bolt vs a rivet or weld

But aren't slip unions cemented and therefore permanent? Is everyone actually using threaded pvc?

 

[fish farmer]

But aren't slip unions cemented and therefore permanent? Is everyone actually using threaded pvc?

The center of the union is threaded and has a o ring.

 

[GlassMunky]

But aren't slip unions cemented and therefore permanent? Is everyone actually using threaded pvc?

You are misunderstanding….
Yes they are glued to the pipe but they still let you remove the entire section of pipe without cutting the pvc.

Example, above my return pump I have a union so that when I need to clean the pump I can just unscrew the union and take that section of pipe out the sump while leaving 90% of my return plumbing untouched.
I can clean the pump and put it right back in the system with no cutting or gluing

 

[VintageReefer]

But aren't slip unions cemented and therefore permanent? Is everyone actually using threaded pvc?

Let’s take a return pump going to a slip bulkhead. It’s cemented to the bulkhead and there is a union somewhere close to the pump. With the union you could remove the pump and pipe up to the union leaving the cemented section in place

 

[exnisstech]

 

[VintageReefer]

Glass munky and I were responding at the same time, with the same thought/explanation!

 

[fish farmer]

You don't have to use a union if you don't want. PVC is very easy so if you want to change something just cut the pipe and either put it back together with a coupling, for about 50 cents or a union for $7.00. It doesn't matter, you can just keep cutting the pipe as much as you want.

Fernco's are my friend.

 

[XLIII]

Oh thanks everyone for the great explanations. Looking at people's assembly build videos and discussions, unions looked like couplings. I can see how if the union itself is threaded the center be disassembled with glued parts on the end. Thanks everyone again

 

[Paul B]

As an example, you can see the unions on these diatom filters I designed. It allows me to remove the pump easily if needed.

 

[exnisstech]

I've have read of them being referred to as true unions.

 

[VintageReefer]

The is my new setup
If it’s stupid then blame the manufacturer lol

 

[bryce.martin]

You don't have to use a union if you don't want. PVC is very easy so if you want to change something just cut the pipe and either put it back together with a coupling, for about 50 cents or a union for $7.00. It doesn't matter, you can just keep cutting the pipe as much as you want.

I wouldnt advise this, the more couplers you use the more resistance and turbulent flow. If you keep patching it up your making the plumbing less and less efficient and making the system work harder.

 

[Paul B]

I wouldnt advise this, the more couplers

PVC couplings do not restrict any flow. The inside diameter is the same as the inside of the pipe. Just my opinion of course.

 

[bryce.martin]

PVC couplings do not restrict any flow. The inside diameter is the same as the inside of the pipe. Just my opinion of course.

Anything that will disrupt flow will restrict, I get that its not as drastic as elbows though. I just come from the world of high performance cars so by nature I wanna eliminate any obstruction if I can avoid it is all.

 

[Paul B]

I understand and iron pipe couplings will slightly restrict or disrupt flow, but not PVC elbows, not even a little.
But it's not that important.
I am also a mechanic and inventor. Also a male model, in my mind anyway.