Joining 1.5 PVC to Copper

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KDpoolguy

KDpoolguy

0
Bronze Supporter
Mar 5, 2017
603
Palm Desert, CA
Pool Size
17000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-9)
Hi All,
I've gotten so much outta TFP that I was more than happy to donate to become a bronze supporter. I maintain my own pool, from repairs to chems, so I really need you folks when I need ya.

Just ventured out and a RWG (repair with goop) I did maybe 3 years ago is leaking again. You can see the staining on the cement, so it's likely been doing this on-and-off for years I'm sure. I cleaned the filter 2 weeks ago, and when empty the filter isn't firmly planted on ground and torques the long PVC run and I'm sure that's how the leak keeps returning.

It's the PVC from filter going into the copper heater inlet. I painted the area white, so it's not new. I presume/hope it's a sweated-in threaded copper adapter (see link) with a threaded 1.5" SCH40 PVC screwed into it with the teflon or other sealant broken down and that's the leak. I covered the leak area it in epoxy 3 years ago (I didn't know what I was doing back then ;)) and I guess it's time to do it right and do a re-plumb.

What's the consensus on how to get a leak-proof threaded connection between copper & PVC? Just teflon tape, or the liquid (yellow goop)? I read also pipe dope? Is there a type? Should I use PVC primer for the threaded area? Will I need to put in a new sweated copper treaded adapter also?

Thanks!

Shop NIBCO 1-1/2-in x 1-1/2-in Copper Threaded Adapter Fitting at Lowes.comLeak 2018.JPG
 
When joining metal and plastic, it’s vital to keep the thermal expansion to a minimum. For copper pipes going into the the heater, you want the metal pipe to be a longer run, 12”-24” or so, to ensure that heat from the header block has time to radiate away a bit and not have a hot copper pipe in contact with the PVC. Also, when joining plastic to metal, you want the metal fitting to be female thread and the plastic fitting to be male thread. This ensures that the metal, which typically expands more than plastic, doesn’t crack the plastic fitting. Finally, I asked an old plumber once which he prefers, Teflon tape or liquid Teflon ? He said “Both!” You put the proper wrap of tape on the threads (don’t over tape it) and then you apply some goop to that. Then you screw it into the FNPT metal connector and you will get a nice and tight seal. I did that with an outdoor spigot I replaced and the seal has be good for years (lots of extreme hi/low temps).

I’d also consider using a transition made out of CPVC or SCH80 PVC. Both can stand higher heat loads and the SCH80 stuff is a thicker wall material. Both can be joined easily to regular SCH40 PVC.
 
So Teflon tape and Teflon sealant together?

It’s so hot here that any exposed and improper joint just flakes and leaks, so this sounds like the best option since the dope remains goopy & apparently doesn’t dry/flake so any torque on that line won’t bust a leak again. That’s why I painted the PVC with white latex, to give the original pipe and joints some sun-screen. As evidence, I have a PVC drain line on the hot roof, with joints I didn’t use primer on, and 3 years in it’s leaking like crazy.

My heater is a vintage 1987 Raypak NG 266k unit built like a brick house like the similar TeleDyne units. I replaced all the electrical & potentiometer components and welded in a new bottom (rust repair) last summer and it works beautifully, but the required copper pipe on inlet/outlet as ‘heat sinks’ has interfered with an SWG install for now—and now this.

I think I’ll go with the CPVC, if only from the copper FPT/CPVC MPT connection down the 3 feet or so until a 90 and SCH40 the rest of the way into the Filter.
Sound ok?
Hope the existing MPT side will back out without enough torque to break the sweated copper! I guess I’ll see when I dig into this.
 
Hard to tell where the copper ends and the PVC starts. But it looks like it's leaking from a PVC to PVC joint? If so, cut the PVC pipe after the joint, unscrew the connector, and replace it with a union. This will let you screw the PVC connection tighter. If it's leaking from a copper joint then do what other have said - replace the copper with a 2" NPT Sch 80 "Nipple" (that's the official term). They are expensive (about $40-$50 - no idea why?) but you don't have to worry about copper joints any more.
 
I can’t really tell either, but it’s leaking from the threaded union. I’m a bit confused now. Do you mean remove the copper fitting?
OK, scraped off and paint and goop and it was deceiving. It's 2.5" Copper MALE threaded nipple and the SCH40 PCV FEMALE threaded onto it.
Leak Copper PVC joint.JPG
You can see the coupling where someone replaced this already years ago, so this seems to be a recurring issue. As Joy mentioned "you want the metal fitting to be female thread and the plastic fitting to be male thread", that's gonna be the issue as it's reversed. Perhaps now with the teflon tape&goop and a CPVC fitting, this will be the fix. It's blazing hot out and I really don't want to sweat in a new copper fitting. I figure I've got another 2-3 years max of my heater, so I don't want to go crazy.

Wow, it is expensive! I’m hunting around the web. So a CPVC SCH80 2.5" socket x FPT I believe is what I should be looking for?

Gotta another ?: If anyone knows a good site to get these fittings? Looks like Home Depot doesn’t carry. I’m just gonna replace that area and a union/coupling and not the entire run. I am now just thinking of plumbing in a in-line flow meter (maybe FlowVis 2 x 2.5in. Complete Pool Flow Meter and Check Valve)? I’m OCD to get flow right ever since I installed the Variable Speed pump.
 
Well, seeing that picture, I'd replace the copper. Get the 2" sch 80 nipple (6" long is usually enough and then connect to sch 40 fitting). You'll also need two rubber flange washers and sleeves made for that manifold to seal it when you re-install it:

Lasco 9220-120 sch80 nipple (cut in half)
Zodiac S0078000 Gasket, Flange 2in.
Zodiac S0078200 Sleeve for 2in. Flange

Confirm that you have a 2" NPT thread on the two heavy brass manifold clamps on the inlet/outlet.

Good luck!
 
Ah, I get what you’re recommending here. That area is rusted, so beyond just new gaskets it’s gonna require the kits for my heater, found one similar kit with new gasket, sleeves, bolts, washers and new brass clamps:
Google Image Result for https://cdn3.volusion.com/hkvs7.73qo2/v/vspfiles/photos/R0031900-2.jpg?1435641069
I’m sure I need a full kit also which is a lot of dough, and I’m sure tearing into the inlet flange may open a can of worms. I got this heater limping along with spit and crummy welds.
It’s also 2”, yes.

I’m sleeping on it, but since I know it’s 2” now, I can R&R with a couple fittings and some 2” PVC tomorrow with what they carry at Home Depot. If it holds, great, otherwise in the Fall I’ll replace the gaskets and the copper and maybe finally plumb in my SWG in the outlet also.
 
You shouldn't need the whole kit, just the gasket and sleeve (3rd image). You can re-use the big brass flanges and bolts, just clean them up good.

PVC is not ideal for connecting directly to the heater flange as it's not a high temperature material (hence the sch 80 nipples).
But if you're just hoping to get another year or 2 out of the heater then you can just replace the existing PVC coupling with a new one and use plenty of teflon tape!
 

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Thanks Keith, really helpful.

On closer inspection you’re right it could just be a gasket/sleeve replacement. It initially looks like cast iron, but when you mentioned it’s like powder coated brass gave me a better feeling about being able to back out/unscrew the copper pipe.

I ordered the gaskets, CPVC 12” long nipple, a CPVC Adapter ($13) FPT & Slip so I don’t need to cut the nipple but also just in case I do it the other way, 2 slip couplings if I wanna cut it, and and some 2” SCH40 pipe. Gonna start tomorrow if it arrives in time.
 
So I began the repairs tonight as the weather is finally mellowing out here. Decided to replace the entire run of PVC from filter to heater as the pipe is oblong and clearly UV battered.

I removed the cast iron flanges and found the copper pipe ‘heat sink’ is “fluted” or tapered and doesn’t physically touch the threaded cast iron flange. It only is sealed to the manifold by the rubber gasket. A pool builder came by last week to show off the work he did on our pool to a potential client and in return asked for his input. He advised a new heater and sent me a bid for $2150, not too bad, but I just wanna fix this leak and get another year or so outta my venerable beast. He said the copper looked to be in good shape from outside and didn’t think threading the CPVC to the old rusty pitted cast iron flange would survive. He said those heaters run really hot, and they were designed with the fluted copper, not touching the cast iron manifold or flange, so even though I think CPVC is fine, especially if the fluted copper wasn’t salvageable, I get the ‘if it aint broke’ argument. The thermal change of cast iron is another I dunno I’d rather not throw into the equation now.

My option was to (1) replace the flange with the new kit ($57) to thread in the CAPRON CPVC, or (2) keep the fluted copper and replace the gasket. I chose the latter, but still using CPVC for the area that originally leaked. I have the hefty 2” FPT CPVC threaded on the male copper now with Rectorseal FTPE paste sealant AND the gray Teflon FTPE tape. I spread the Rectorseal on the MPT & FPT, finger pressing and spreading it into all threads, then wrapped MPT copper in gray Teflon tape and tightened it on voila. This thing shouldn’t leak now. The flange and new gasket is all bolted in.

I’ll finish glueing in the SCH40 run tomorrow morning, or that was the plan until I gashed my finger...oh it hurts!

I found online Laars parts for these fluted copper heat sinks (also in Stainless). They only have them in strange 90s but nice to know I could still find them. These heaters were born to survive, and having one last true solid state mechanism that isn’t computer controlled or somehow linked to the internet is refreshing. Live long RAYPAK VERSA!
 
Nice job!

Not to be overly technical but the “fluted” end is called a “flare” fitting. One uses a swagging tool to flare the end of a copper pipe to the appropriate diameter to fit onto the receiving end of another pipe or manifold. They are used in water and gas applications.

There’s a company called Swagelok whose entire product portfolio is nothing but various pipe, fitting and manifold products for industrial application....I spent many a day perusing the Swagelok catalogues for my various engineering endeavors....
 
PoolguyinCT said:
American Granby Inc. Flo 1 1/2" IPS Socket X 1 1/2" CTS Copper To PVC With Flo Lock Adapter (#935-15)
Click to expand...

It’s like adults playing with LEGO bricks....you just keep rummaging through the box until you find the right pieces.

Is LEGO still headquartered in Enfield?
 
b06013c1ef799b90c26b11779692ed90.jpeg

All wrapped up. Waiting to dry then will check for leaks. A fairly easy repair since I had the new filter connections.
More future fixes I’d appreciate help with:

-Take a look at the AFTER image and the inlet to the pump. There’s a darn reducer that goes from 2 inch to a 1.5 inch for just 6 inches the into the pump inlet. I didn’t do that when I installed my Hayward Tristar VS, as it was a plug and play from the old Sta-Rite single speed pump. Probably all they had was 1.5 in., but isn’t this gonna be unnecessary head loss? From initial inspection I’d have to dig out to get to below ground 2 inch pipe to redo the 90. It’s been repaired at least twice and I see they used the reducer so they wouldn’t have to dig—they could only make a clean PVC connection only using the inside male/male slip coupling.

I know my initial pipe size was way off (thought it was all 1.5, but it’s 2 inch, I’m sure I’ve got unnecessary head loss, right?
Since replacing this run, and seeing how badly misshapen and mushy-brittle the existing PVC is, I’m gonna do the rest of the exposed PVC.

The PENTAIR bulkhead union couplings at the pump and lfilter can handle the 3” PVC outside or 2” inside, right? Or is it 2.5” outside?
https://www.amazon.com/Pentair-270004-Bulkhead-Replacement-Cartridge/dp/B004VTGLRM

Our equipment pad is right behind our bedroom, so Gonna heed the 3 inch pipe experience of lowered noise on the Pump to Filter run.

On high RPM, the pump and water noise can be annoying. I’d replace the inlet to 2 inch, and have 3 inch pipe from the short 2 foot run from pump outlet to filter inlet.

Any guidance on this route? I’d have to order the 3” pipe as 2” is max our home improvement shops carry.
 
Ur not gonna gain anything for that short 3" pipe run. By the time u adapt the 3" and buy a stick and the fittings to go back to 2" u spent more than u will ever save tenfold. 2" pipe thru out is ideal for what u have and is alot better than 1.5"
 
KDpoolguy said:
I can’t really tell either, but it’s leaking from the threaded union. I’m a bit confused now. Do you mean remove the copper fitting?
OK, scraped off and paint and goop and it was deceiving. It's 2.5" Copper MALE threaded nipple and the SCH40 PCV FEMALE threaded onto it.
View attachment 84233
You can see the coupling where someone replaced this already years ago, so this seems to be a recurring issue. As Joy mentioned "you want the metal fitting to be female thread and the plastic fitting to be male thread", that's gonna be the issue as it's reversed. Perhaps now with the teflon tape&goop and a CPVC fitting, this will be the fix. It's blazing hot out and I really don't want to sweat in a new copper fitting. I figure I've got another 2-3 years max of my heater, so I don't want to go crazy.

Wow, it is expensive! I’m hunting around the web. So a CPVC SCH80 2.5" socket x FPT I believe is what I should be looking for?

Gotta another ?: If anyone knows a good site to get these fittings? Looks like Home Depot doesn’t carry. I’m just gonna replace that area and a union/coupling and not the entire run. I am now just thinking of plumbing in a in-line flow meter (maybe FlowVis 2 x 2.5in. Complete Pool Flow Meter and Check Valve)? I’m OCD to get flow right ever since I installed the Variable Speed pump.
Click to expand...


It is recommended that you never thread a metal male pipe fitting into a female plastic pipe fitting because the metal will split the plastic if over tightened. Male plastic into female metal is acceptable.

Mike.
 

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