Pool pump transition fittings

miamicuse

Well-known member
May 26, 2019
53
Fort Lauderdale, Florida
I have two questions about plumbing pool piping to a pump.

(1) I have a pool pump with 2" threaded inlet and outlet connections, however, my piping orare 1.5". I wanted to use those hi-temp unions to allow me to uncouple the pump for service if necessary. So I need to transition from 2" to 1.5" somewhere. So first question is, do they make a hi-temp union that is 2X1.5? I did a search and could not find one.

(2) If there is not a reducing hi-temp union, then I need to transition from 2 to 1.5 somewhere probably at the end of the 2" union I can transition to 1.5, what is a good fitting to use? A 2X1.5 PVC bushing? or a 2X1.5 reducing coupling which will provide a more gradual transition? May be it doesn't matter.

(3) This is more a general question. I looked at many pool plumbing examples to get an idea what others do, and one thing that really puzzled me was how many pictures I saw online used drain fittings and even no hub rubber couplings. This is very surprising as drain fittings are not designed to be pressurized and their hubs are much shallower than standard pressure fittings. Why is that? I do get that when a pump is running, there is an open end to the pool, so the pressure is not as high as a domestic water line where pressure may be 45psi or higher and when no fixture is running there is a constant pressure, but still, I wouldn't expect drain fittings to be used. Are people using drain fittings because the fittings have less friction loss due to the gentle sweep angle and that is a bigger advantage over the pressure fittings?
 

cowboycasey

Gold Supporter
LifeTime Supporter
TFP Guide
Jul 3, 2013
4,565
Fletcher, OK
I bet you have a 1.5 inch in your pump, most all of them do and that is what I used on all my pump fitting and all my fittings in the pool... Here is a 1.5 x 1.5 inch hi temp union that should work perfect :)


3. most do not know or do not care that they are using them.. they should not be used and whenever we see them we let people know they should be changed out... :)
 

miamicuse

Well-known member
May 26, 2019
53
Fort Lauderdale, Florida
I bet you have a 1.5 inch in your pump, most all of them do and that is what I used on all my pump fitting and all my fittings in the pool... Here is a 1.5 x 1.5 inch hi temp union that should work perfect :)

My pump's inlet and outlet have two sizes, the outside is a male threaded 2.5" and the inside is threaded female 2". The existing piping (which I am taking apart) uses the 2" and threads in a 2" female adapter, then a piece of 2" pipe, then a 2" PVC union, and coming out of the union is a 2X1.5 bushing. I am trying to simplify this by eliminating the union and changing to a hi-temp union. I am tempted to take a 2" hi-temp union and solvent weld a 2X1.5 bushing to it, unless I can find a 2x1.5 hi temp union. Thanks for the link to the 1.5 2 pack hi temp union I will keep that in mind.
 

miamicuse

Well-known member
May 26, 2019
53
Fort Lauderdale, Florida
Just curious; why is "high temp" needed?
In my case it is needed because I am hoping to solve two problems.

(1) This is just to simplify the series of fittings, because I have a PVC union on the inlet and outlet side and by using a hi-temp union I can remove two extra fittings.

(2) The more important reason is there is a leak on the outlet side connection. Very slow leak, sometimes it goes away, sometimes it comes back, I have a 2" male adapter going into it, and no matter what I do with that threaded connection, I tried PTFE pipe sealant, PRFE tape, thicker tape, thinner tape, tape and dope together, swap to a new male adapter, the is more than a 50/50 chance the leak comes back within a week or two, although once it was leak free for 2 months. After all the failed attempts, I read online somewhere that my particular pump may have a defect in the outlet connection which may be solved by a hi-temp union, not because of it being "hi-temp" but because it seals with a compression gasket.