Threaded fittings, reasonable?

themartb

Member
Jul 31, 2017
7
Philadelphia, PA
Hi All,


I'm expecting to have to replace the pump for my inground pool this fall, and it's going to involve a fair amount of plumbing replacement as far as I can tell. Most of the PVC is really ancient, brittle feeling, and likely won't survive removal of the old pump. It's all 1.5" PVC, planning to do new ball valves for three suction lines (2x skimmer, 1x bottom drain), the new pump, and a new push-pull backwash valve on the FNS Plus DE filter.


My question: Would it be unwise of me to try to use threaded connections everywhere I can, rather than the usual slip/glue joints? I feel like the ability to disassemble everything seems really valuable. But worry that it might introduce complications, like increased chance of suction side air leaks or something like that? (fixable with teflon tape?)

Curious what folks thoughts are. Don't recall seeing it discussed anywhere before.
 

jblizzle

Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
43,238
Tucson, AZ
:wave: Welcome to TFP!!!

I would suggest trying to use slip fittings whenever possible ... much easier to get a good seal. Many pump have the option to connect the plumbing with unions instead of a threaded fitting ... pay for the union fittings. Or, add your own unions wherever you might want to pull the plumbing apart.

I would also recommend going to a multi-valve on the filter instead of the push-pull to have more options, like a waste function and recirculate function.

Finally, I would recommend going to Neverlube-type valves (2-way or 3-way) on your suction lines as they are rebuildable and will not stiffen and break like typical ball valves. I would put a 3-way between the 2 skimmers and another 3 way between the drain and the skimmers. Or you could just put a 2-way on each of the 3 suction lines.
 

smracing

Well-known member
Jun 1, 2011
237
Carlsbad, NM
Use glue fitting with unions where you would like to be able to disassemble. The pump inlet and outlet, filter connections, heater, etc.
 

themartb

Member
Jul 31, 2017
7
Philadelphia, PA
Wow, thanks for the responses!

Unions: So it's a slip/glue attachment to pipe, but an o-ring/threaded coupling of the sections. Absolutely makes sense. However, they look like they may be bulkier than my configuration allows, which I may have intuitively known and so tuned them out. I'll review the geometry with this specifically in mind.

@jstephens1 ... I wouldn't know how to spot a good union from a poor one, any specific advice, what to look for?

Threaded fittings: So if using direct threaded connections, no o-ring involved as with a union, risk of vacuum leaks is substantially increased?

Multi-Valve for the filter: I have an open mind about them ... but I very much lack education, I've seen them online but don't comprehend what functions they offer ... I struggle to conceive of what you'd even need beyond normal circulation (to chorinate/skim/heat-balance) and waste (backwash dirty filter DE out)?
 

jblizzle

Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
43,238
Tucson, AZ
Multi-port settings that would be new from to you from the push-pull:
Waste: Pumps directly from the pool, skips the filter and goes right out the waste pipe. Allows you to vacuum large amounts of dirt that would clog the filter. Allows you to drain off water
Recirculate: Pumps from the pool, skips the filter and goes right back to the pool. Useful if you have a filter problem and want to keep circulation going. Useful when fighting swamp to get all the algae killed before you start filtering, since algae will clog up a DE filter VERY fast
Rinse: Pumps from the pool through the filter the normal direction and out the waste pipe. Allows you to alternate between backwash and Rinse to get more of the debris and DE out of the filter with no chance of any going back to the pool.
 

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xyz

Gold Supporter
Sep 8, 2016
641
Escondido/CA
Also, take a look at the Quad DEs. Almost all the benefits of a cartridge filter, all the benefits of a DE filter, and few of the downsides.

Also, for me it was easier to get an oversize filter [A 40 would work, I got an 80], and this added two really nice benefits.

  1. Less electricity costs. I was able to drop by pump power by more than 3:1 because the low back pressure allowed me to get good flow to my SWG at quite a bit lower power [RPM] setting.
  2. Much greater time between cleaning. My old [FNS] one was best if cleaned quarterly, but I could get away with 2x per year. I cleaned my new one after 9 months, because it had been so long, and it really didn't need cleaning at all. I'm now going to clean it once a year, just because.

Benefits:

  • Much easier to clean than the FNS. Pull 4 cartridges, hose them down, rinse out filter body, reassemble, add DE.
  • Of course, that ultra polished DE crystal clear water.
  • High flow, low pressure, so cheap to run

Also, some have been installing the Quad DEs without a valve. If you never need to vacuum to waste, and you don't backwash [and why backwash if your filter works this great for this long?].

I know Brian has one, he had a valve, and eventually cut it out and hard plumbed it.

No valve might give you a bit more room for unions too.

I'll try to find my installation so you can see the trouble I had. ;-)

- - - Updated - - -

https://www.troublefreepool.com/threads/128419-Here-goes-Quad-DE-80-upgrade/page2
 

themartb

Member
Jul 31, 2017
7
Philadelphia, PA
An interesting concept ... fortunately I'm not looking at a new filter, my FNSP 36 is less than 5 years old and seems to work like a champ. (btw, images aren't showing in that linked thread, for me at least)

The central problem I have is leakage from the outlet connection of the pump, but there's a bit of a domino effect just waiting. It looks like the pump outlet's threaded-fitting is cracked. It's old and brittle, so I anticipate it shearing completely off when I attempt to unscrew it. Then the threaded portion will be left behind in the pump outlet, at which point I'll probably make an unsuccessful attempt to use a chisel at an angle to try and unscrew it. When that fails it's new pump time ... which precipitates the suction-side valve replumbing, and is a convenient time to replace the backwash valve just because it's seized and needed it anyway.

Can't wait, lol.
 

themartb

Member
Jul 31, 2017
7
Philadelphia, PA
Just had a thought - I notice many pump designs have the inlet and outlet ports very similarly positioned, is this an actual standard? Are they configured to the same dimensions?
 

jblizzle

Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
43,238
Tucson, AZ
Pump port positions are not standard across brands and pump line. Although sticking with the same brand and pump type should align.

Please add your pool details to your signature as described HERE as it will help us help you.
 
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