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Thread: Did a dry run blowing out lines

  1. Back To Top    #1

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    Did a dry run blowing out lines

    I thought I would post up a description of a dry run I did blowing out the lines on my pool in prep for closing next month. In the past, I've paid the pool guys to do the close, but this year I thought I would give it a shot and use the $250 elsewhere!
    Now, my pool plumbing is pretty simple so it may not work for everyone, so I'll give a brief description of how it's plumbed. I have 3 returns, 1 skimmer, and one side wall suction on a vinyl pool. The plumbing is 1.5", and each line is a separate run back to the pad. The 3 returns are tied together just under the ground near the pump pad with a "3 into 1" fitting that's 2 inch by 1.5" times 3. No valves (I plan on remedying that next spring). The main suction and skimmer are plumbed on 1.5" lines back to a 3 way valve so i can put the suction between either the skimmer, main, or both. So....pretty simple set up, really.

    I used a pretty cheap Craftsman pancake, 6 gallon. It pressurizes to 150 psi, and has a regulator I cranked down to 20 psi. I blew from the pump using a brass nipple screwed into one of the drains. I screwed a male compressor hose fitting like this onto the nipple.


    That attached to the female end of the hose that was connected to the tank. Before I made the connections, I opened the pump strainer lid and drained most of the water, and put the multiport valve on the sand filter to RECIRCULATE. Once the air was going, I cranked the regulator up to 20 psi to add air to the lines.

    The return closest the pad blew first. Once that was plugged, the next closet return blew, then the main side wall suction, then the far side deep end return, then the skimmer last. The compressor was running thr entire time, but I never lost pressure since the tank stayed around 35-40 psi, and the output was at 20. I'm not sure if a smaller capacity tank would have kept up, but as long as the input is higher than the output, it should be ok. Since I know my compressor will blow the lies with no issue, I feel confident that everything should go smoothly.
    Famous last words!
    14,000 gallon IG, Vinyl. Hayward 3/4 hp superpump, Penatair IC40 SWCG, Pentair automation, Hayward sand filter, Aqua Comfort heat pump, Hayward 400k Lo-Nox LP heater.

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    Re: Did a dry run blowing out lines

    Word of caution when blowing lines with a compressor. They don't usually blow enough volume to displace all the water. It may only form a tunnel in the pipe.. It can blow a hole in flex pipe. Line blowing is best done with a high volume of low pressure air. Compressors generate low volumes of high pressure.

    Scott
    Owner of - PoolGuyNJ LLC
    Expert Pool and Spa Repairs, Renovations, and Augmentation. Helping people decide what is the right gear for meeting their needs. Expectations Set, Expectations Met, No Surprises.

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    Re: Did a dry run blowing out lines

    The water was bubbling pretty good, as good as the mighty vac the guys used last year. And I had the pressure set to around 20. Besides i dont have flex below ground, either. I've seen guys blow lines with compressors before. If black poly wont take 20 psi, then the filter pump would blow it apart. Besides, there isnt 20 pounds on the line, either at any given time, you know that My lines are fairly short runs so the pipes should be pretty full of air. As long as the tank kes more air pressure than whats on the regulator, it will work just fine, IMO. I'm sure if someone has more complicated plumbing, it might not work. Thats why I prefeced everything with the plumbing setup.

    Even if a little water is left, it will sink to the lowest point, which is about 4 feet down. It doesnt freeze that deep, even in central Mass.
    14,000 gallon IG, Vinyl. Hayward 3/4 hp superpump, Penatair IC40 SWCG, Pentair automation, Hayward sand filter, Aqua Comfort heat pump, Hayward 400k Lo-Nox LP heater.

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    Re: Did a dry run blowing out lines

    It's more about volume based displacement than pressure based. My blower, or even the blower end of a good shop vac will move a lot more air per minute through an 1-1/4" line (the size off my blower and shop vacs btw) at 4 PSI than the thin hose off a compressor's storage tank at 20, 30 or even 50 PSI.

    If there was a solid separator between the water in the pipe and the air being injected, the compressor would win a larger column of water moved contest but this is not the case when blowing out the lines of a pool.

    Scott
    Owner of - PoolGuyNJ LLC
    Expert Pool and Spa Repairs, Renovations, and Augmentation. Helping people decide what is the right gear for meeting their needs. Expectations Set, Expectations Met, No Surprises.

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    Re: Did a dry run blowing out lines

    As I said, I've seen pool guys blow the lines just as I have done. In fact, I believe Matt Heck on this site does it the same way. I'm confident everything will be fine.
    I understand what your saying, but my understanding that it would only apply to blowing high pressure thru the "thin hose" directly into a pipe full of water. However, by blowing air through a "vessel" (in this case the pump) and bringing that vessel up to a constant pressure, the volume of air moved is much higher than just blowing air directly into a line. By blowing though a closed pump, it wouldnt matter what the source of air is (either 15-20 psi off of a compressor, or off of a shop vac), as long as the pressure in the tank stays above the pressure on the regulator, and the tank doesn't run out of air, the line should be pretty much free of water. At least thats what my engineer next door neighbor said when I described the idea. I think mayhe this might be a case of thinking something is true because thats what people have always heard. Just my opinion i guess.

    I'm glad you like what works for you. I just reported what I encountered when i tried it, thats all.
    14,000 gallon IG, Vinyl. Hayward 3/4 hp superpump, Penatair IC40 SWCG, Pentair automation, Hayward sand filter, Aqua Comfort heat pump, Hayward 400k Lo-Nox LP heater.

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    Re: Did a dry run blowing out lines

    I should add that when I winterize a Paramount floor system with 2" pipes, the special winter plugs require the use of a compressor. A&A's floor systems may but usually won't as they can be plugged at the distribution junction before they fill back up. The floor jets won't let much water back in the pipe before it's air locked. As long as the floor pipes are air locked below the frost line, life is good.

    Matt uses the same type of blower I use.

    Scott
    Owner of - PoolGuyNJ LLC
    Expert Pool and Spa Repairs, Renovations, and Augmentation. Helping people decide what is the right gear for meeting their needs. Expectations Set, Expectations Met, No Surprises.

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    Re: Did a dry run blowing out lines

    [quote="PoolGuyNJ
    Matt uses the same type of blower I use.

    Scott[/quote]

    I went back and looked at his post. you are correct, but he does recommend a compressor too, so i think i'm good. Durk uses one too with no issue.
    14,000 gallon IG, Vinyl. Hayward 3/4 hp superpump, Penatair IC40 SWCG, Pentair automation, Hayward sand filter, Aqua Comfort heat pump, Hayward 400k Lo-Nox LP heater.

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    Re: Did a dry run blowing out lines

    I agree. My compressor kicks the water ten feet up from the skimmers. How much higher can the blower type go? And who cares? I'm pretty sure both methods are going to leave about the same amount of water in any given length of pipe. I never use anti-freeze, either. I admit my return runs are short, and a longer one might present a bigger challenge.

    At the end of the day, it is neither air volume nor pressure that is the determinant of performance. It is the speed of the air as it exits the line at the far end, which is a function of both the pressure and the volume injected at the blowing end. You can pretty much tell if you are getting all the water possible out by observing what goes on at the far end and by stopping and re-starting. If you keep getting a new hunk of water each time you start again, there is a dangerous amount of water still in the line. If you just get air and no water coming out on a new blow, that line is as clear as it is going to get.
    Current: 28,000G 18'x36' I/G AnthonySylvan Plaster; Waterway 60 sq.ft. DE Filter; 1.0hp x 1.65 SF Two-Speed (B2982) WhisperFlo; 2004-Present
    Previous: 40,000G 20'x40' I/G Koven unlined WWII salvage 5/8" marine steel; Lomart Stainless Sand Filter; 3/4hp Hayward SuperPump; 1946-2003 (managed by me from about 1964)
    Ancient Taylor K-2000, upgraded with Taylor CH, TA, and FAS-DPD, and TFT CYA tests.

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    Re: Did a dry run blowing out lines

    Yea, I agree with you Durk. When I unplugged the lines after I did my test, I unplugged the far return first. The thing gurgled air for at least 20-30 seconds, so I assume most of the water was out. Besides, my lines go down about 4 feet at the lowest point. Even if a little water stayed in the lines, it will seek the lowest point, which is below where any freeze would occur. Water line depth up here is 5 feet according to code, but thats belt and suspenders. In practicle terms, we dont get a freeze below 3-3.5 feet, really.
    14,000 gallon IG, Vinyl. Hayward 3/4 hp superpump, Penatair IC40 SWCG, Pentair automation, Hayward sand filter, Aqua Comfort heat pump, Hayward 400k Lo-Nox LP heater.

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