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Thread: Drilling and tapping PVC to add injection point

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    Drilling and tapping PVC to add injection point

    My Stenner pump came in yesterday and now I am ready to install. I plan to tap into my return line somewhere downstream of my heater. My question is: should I tap into the PVC pipe or should I tap into a PVC fitting (90 or elbow)? The PVC fittings are thicker than just the pipe and therefore should allow my plastic for me to cut threads and make a more stable injection point. But I may be overlooking something. Any advice? I don't want to mess this up.
    14,800 gallons in-ground vinyl. sand filter. 1.5 hp pump

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    Mod Squad tim5055's Avatar
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    Re: Drilling and tapping PVC to add injection point

    I avoided tapping by just installing a "T" in the return line.

    Wish I could answer your question for you. You point about the thickness of a fitting seems logical.
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    Re: Drilling and tapping PVC to add injection point

    Like tim5055, I also added a tee and unions. Installing the union was a pain for me. I do have a psi gauge, which is tapped into a fitting, not the pvc pipe.
    39' x 18' IG 3.5X4.5X9 34k gallon w/ raised spa, 3 stone scupers
    Jandy 60 SqFt DE, Jandy PDA PS6, Jandy JXi400 heater, Jandy 2.0 EPump w/SVRS
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    Re: Drilling and tapping PVC to add injection point

    In my 50 years of experiences in the machine shop, tapping a tapered thread into the side of a pipe is a recipe for aggravation and leaks.....

    What you want is an ? X ? X 1/2 reducing tee, where the "?" is a slip (glued) fit appropriate to the size of your existing plumbing and the 1/2 is a female tapered pipe thread. From that starting point, anything else should be possible.....

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    Mod Squad Bama Rambler's Avatar
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    Re: Drilling and tapping PVC to add injection point

    My pool is plumbed with schedule 40 PVC pipe so I just drilled and tapped a hole for the injection fitting right in the side of the pipe after the filter ( I don't have a heater). That pipe is plenty thick to handle the tapped fitting.

    I've also read about people drilling and tapping a fitting for the reason you noted (it's thicker), but to me it's not a concern.
    Dave J. TFP Moderator
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    Re: Drilling and tapping PVC to add injection point

    There is no slack in my plumbing to install a slip T. I would have to install two unions on the ends of the T and that seems like a recipe of added air leaks. I guess I can always just try to tap the pipe and if it causes problems, I can cut out that portion and then install the T. Thanks for the help.
    14,800 gallons in-ground vinyl. sand filter. 1.5 hp pump

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    Re: Drilling and tapping PVC to add injection point

    If committed to that adventure, my suggestion would be to use the smallest pipe thread available.....

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    Re: Drilling and tapping PVC to add injection point

    image.jpg

    Went and checked plumbing. Saw this screw out port on the downstream side of my heater. Could I put a bushing in here and use it as the injection port? Am I looking at it wrong?
    14,800 gallons in-ground vinyl. sand filter. 1.5 hp pump

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    Patrick_B's Avatar
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    Re: Drilling and tapping PVC to add injection point

    No, that is way too close to the heater/exchanger for injecting any chemical. I would not do that.

    Even if I had no choice to put it on a heater run leg, I would want a check between the injection point and the heater. With the check being upstream of the injection point.
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    Re: Drilling and tapping PVC to add injection point

    Not only that, but as far as it is screwed in, I would be afraid it is a straight pipe thread using an o-ring for sealing....

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    Re: Drilling and tapping PVC to add injection point

    Thanks for the advice. I'll avoid that spot. So the outlet pipe from the heater runs about 2 feet then angles into the ground. Is this the pipe where I need to inject?

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    Patrick_B's Avatar
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    Re: Drilling and tapping PVC to add injection point

    Yes, downstream of the heater on the outlet. If you did decide to slip in a tee with unions, you have no worry about an air leak, since it's on the discharge side. If it were mine, I would insist on a check between the heater and injection point.
    TFP Moderator
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    Re: Drilling and tapping PVC to add injection point

    Quote Originally Posted by Patrick_B View Post
    Yes, downstream of the heater on the outlet. If you did decide to slip in a tee with unions, you have no worry about an air leak, since it's on the discharge side. If it were mine, I would insist on a check between the heater and injection point.
    Alright, just what I needed--a plan of action. I will move down the heater discharge line about 12 inches and install a check valve. Then downstream of the check valve, I will install a T between two unions with female threads looking up as a place to inject my chlorine. Seems straightforward enough. I will upload a pic when I am done. Thanks for all the help.
    14,800 gallons in-ground vinyl. sand filter. 1.5 hp pump

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    Re: Drilling and tapping PVC to add injection point

    Take pics when done! I always enjoy stenner builds.
    IG gunite/plaster pool/spa Started 1/17/14, Plastered 5/16/14
    Size: 12'-21'x39' free form, depth ranging from 4' to 7, attached 6 person spa with spillover.
    Equipment: Whisperflo 2hp pump, Pentair 30" sand filter, Pentair Mastertemp 400k BTU heater, 1hp Whisperflo for waterfalls, and a blower for spa floor

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    Re: Drilling and tapping PVC to add injection point

    Quote Originally Posted by squib View Post
    Alright, just what I needed--a plan of action. I will move down the heater discharge line about 12 inches and install a check valve. Then downstream of the check valve, I will install a T between two unions with female threads looking up as a place to inject my chlorine. Seems straightforward enough. I will upload a pic when I am done. Thanks for all the help.
    At 12" from the heater, a check valve is not needed. You won't be injecting with the pump off. My injection point is in a tee about 30" from the heater outlet.
    36' x 18' 20k in ground, Finest Finish grey plaster, Pentair Tagelus 100D sand filter, Hayward Northstar 2hp pump, Jandy LRZ125EN heater, spill over spa, iaqualink controlled automation, Stenner chlorination, natural rock and flagstone coping, 1" glass mosaic waterline tile, SR Smith Vortex slide.

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    Re: Drilling and tapping PVC to add injection point

    Got it all put in last evening in about 30 minutes. Decided against the check valve after I cut into the PVC and found that it had no water in it when the pump wasn't running. The angle of the pipe, I assume, means the water drains into the pool when the pump stops. As such, there appears to be no way water could back up into the heater.

    Ran the pump on 5 for two hours this morning, and my FC jumped from 3.5 to 6. I have now turned it down to 2.5 and will try running it for about 2 hours a days and see where this maintains my FC.

    Here are the pics for those that asked.
    image.jpg

    image.jpg
    14,800 gallons in-ground vinyl. sand filter. 1.5 hp pump

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