Worth it to change PVC fittings to improve flow?

[rootusrootus]

I bought my pump & filter as a combo, and even though it is 1.5hp, it seems to only be rated as 54gpm. Seems low. Given that I have the equipment installed about 20 feet from the pool, with 1.5" pipes, I figured I better find out what kind of flow I was actually seeing. It matters to my heater, for one.

So I bought a flow meter, and hooked it up today. On high speed, I see 35gpm. Low speed, 15gpm. I have been ... <cough> ... running on low speed with the heater. According to Raypak, it should be 20gpm minimum. Whoops! Didn't throw any errors, outlet temperature was a nice 12* rise over inlet, but still, it is below spec. And, assuming the pool is 10500 gallons, at 15gpm it takes most of 12 hours to turn over the entire pool.

So I got to looking around, and it -seems- like there is possibly a fair amount of improvement to be had in changing out some of my choices for fittings. Being a bit lazy, I used 90s for most everything. Standard, short radius 90s. Switching to a pair of 45s, or even better a long sweep 90, would that make a noteworthy difference, you think? If I can plausibly raise the low speed GPM up to 20 or even higher, I'll tackle the plumbing work to make it happen.

Since y'all like pictures (I'm with you, I do too!) here you go. Go easy on my wiring, today I'm reworking my bonding wires and they're a bit of a mess until I tidy it up. Also trying to figure out why I can't get my sand filter back down to 13 psi and why it leaks from the discharge port even though it's only a couple months old. Building a pool is fun!

 

[1poolman1]

I bought my pump & filter as a combo, and even though it is 1.5hp, it seems to only be rated as 54gpm. Seems low. Given that I have the equipment installed about 20 feet from the pool, with 1.5" pipes, I figured I better find out what kind of flow I was actually seeing. It matters to my heater, for one.

So I bought a flow meter, and hooked it up today. On high speed, I see 35gpm. Low speed, 15gpm. I have been ... <cough> ... running on low speed with the heater. According to Raypak, it should be 20gpm minimum. Whoops! Didn't throw any errors, outlet temperature was a nice 12* rise over inlet, but still, it is below spec. And, assuming the pool is 10500 gallons, at 15gpm it takes most of 12 hours to turn over the entire pool.

So I got to looking around, and it -seems- like there is possibly a fair amount of improvement to be had in changing out some of my choices for fittings. Being a bit lazy, I used 90s for most everything. Standard, short radius 90s. Switching to a pair of 45s, or even better a long sweep 90, would that make a noteworthy difference, you think? If I can plausibly raise the low speed GPM up to 20 or even higher, I'll tackle the plumbing work to make it happen.

Since y'all like pictures (I'm with you, I do too!) here you go. Go easy on my wiring, today I'm reworking my bonding wires and they're a bit of a mess until I tidy it up. Also trying to figure out why I can't get my sand filter back down to 13 psi and why it leaks from the discharge port even though it's only a couple months old. Building a pool is fun!

You may get some improvement, but the biggest issue you have is what you are asking of an above-ground pool pump remotely mounted far from the pool. There is much more to a pump's capability than its rated horsepower (essentially how much power it consumes). A good half-horse inground (if you could find such a thing anymore) pump could pump considerably more water than a 1.5hp above ground pump on your system given all the fittings, and plumbing you have. You may want to look to upgrade that before making a lot of plumbing changes. Your pump and filter system was designed to sit right at the pool.

Is the leak at the backwash line? Could be debris stuck in the spider gasket in the valve. With the pump off, push the handle down and spin the valve in one direction only a few times. It can help clear a piece of debris. Never move the handle with the pump running and try to always turn the handle clockwise or counter-clockwise only every time when changing positions. Seems to make the gasket last longer.

With the pump running on LOW, you could just push down on the handle to release pressure on the gasket for a "quick second." Don't turn the handle and it also might flush some debris. Those are just things I have done that have worked in the past.

 

[Newdude]

Switching to a pair of 45s, or even better a long sweep 90, would that make a noteworthy difference, you think?

Not one bit IMO. Sweeps and 45s are needed in gravity fed drain applications, or in the miles and miles of street plumbing, getting to your neighborhood. You have 150 hard 90s inside your house because on short runs, they don't matter.

 

[Jimrahbe]

Root,

I am of the opinion that replacing the 90's would not make enough difference for you to even notice.

As long as your heater works, I doubt that increasing the GPM would make any difference either.

There is just no reason to run your pool based upon "Turnovers". You need to run your pump for a reason. Run it long enough to generate the chlorine that your pool needs is a reason. Running it long enough to heat your pools is a reason. Running it long enough to skim your pool is a reason.

Thanks,

Jim R.

 

[1poolman1]

I bought my pump & filter as a combo, and even though it is 1.5hp, it seems to only be rated as 54gpm. Seems low. Given that I have the equipment installed about 20 feet from the pool, with 1.5" pipes, I figured I better find out what kind of flow I was actually seeing. It matters to my heater, for one.

So I bought a flow meter, and hooked it up today. On high speed, I see 35gpm. Low speed, 15gpm. I have been ... <cough> ... running on low speed with the heater. According to Raypak, it should be 20gpm minimum. Whoops! Didn't throw any errors, outlet temperature was a nice 12* rise over inlet, but still, it is below spec. And, assuming the pool is 10500 gallons, at 15gpm it takes most of 12 hours to turn over the entire pool.

So I got to looking around, and it -seems- like there is possibly a fair amount of improvement to be had in changing out some of my choices for fittings. Being a bit lazy, I used 90s for most everything. Standard, short radius 90s. Switching to a pair of 45s, or even better a long sweep 90, would that make a noteworthy difference, you think? If I can plausibly raise the low speed GPM up to 20 or even higher, I'll tackle the plumbing work to make it happen.

Since y'all like pictures (I'm with you, I do too!) here you go. Go easy on my wiring, today I'm reworking my bonding wires and they're a bit of a mess until I tidy it up. Also trying to figure out why I can't get my sand filter back down to 13 psi and why it leaks from the discharge port even though it's only a couple months old. Building a pool is fun!View attachment 455862View attachment 455863

Friction Loss In 2" PVC Fittings​

2" short radius 90 degree ell = 5.5 feet

2" 45 degree ell = 2.8 feet

2" long radius 90 ell (sweep elbow) = 4.3 feet

2" street ell (slip x spigot) = 8.6 feet

On paper, and not seeing all the short radius 90's you have (some underground, etc.) the numbers say you could save about 20' of head. In the real world, you likely would not notice a difference, especially at a low speed. Water speed is a huge part of the head on a system and seldom ever considered in calculations. Even the numbers in the chart are base on a certain water speed (probably 7fps).

 

[rootusrootus]

You may get some improvement, but the biggest issue you have is what you are asking of an above-ground pool pump remotely mounted far from the pool. There is much more to a pump's capability than its rated horsepower (essentially how much power it consumes). A good half-horse inground (if you could find such a thing anymore) pump could pump considerably more water than a 1.5hp above ground pump on your system given all the fittings, and plumbing you have. You may want to look to upgrade that before making a lot of plumbing changes. Your pump and filter system was designed to sit right at the pool.

That makes perfect sense, thanks for the explanation. I had thought the biggest difference was self-priming vs manual priming, but it makes total sense that the plumbing requirements for a typical inground pool are going to be considerably more involved than a typical above ground pool. And what I've done is created a little bit of a hybrid by doing complicated plumbing far away from an above ground pool. I'll put a variable flow in-ground pump on my wishlist . Then I'll have to figure out how to adapt my DIY controller for it, but as a computer nerd that is my favorite type of problem to solve anyway.

Is the leak at the backwash line? Could be debris stuck in the spider gasket in the valve. With the pump off, push the handle down and spin the valve in one direction only a few times. It can help clear a piece of debris. Never move the handle with the pump running and try to always turn the handle clockwise or counter-clockwise only every time when changing positions. Seems to make the gasket last longer.

With the pump running on LOW, you could just push down on the handle to release pressure on the gasket for a "quick second." Don't turn the handle and it also might flush some debris. Those are just things I have done that have worked in the past.

Yep, it dribbles out the end of the backwash hose. Thanks for the tips, I'll give those a try. And I'll remember in the future to only turn the handle one direction when changing modes.