I need a pump that gives good head!!

[not2hye]

Central California.

It’s more of a Mediterranean climate.

Bakersfield. That’s desert.

 

[dave_dj1]

Most people just hook them to the pool pump and let it do the work. You could probably fashion a hydraulic ram pump.

 

[4x4orbust]

This looks like it could work although I was trying to stay away from an on-demand pump. HOnestly, not sure how that will work with my application. I basically want it to run when the sun is up off a solar panel continuously. I cant find the head spec on it either but if you use it everyday, you think that it will pump the water up 9-10 feet without issue?

Given the operating psi, and the fact that it dry primes up to 6 vertical feet, it should be able to pump it up 10’. Your gpm might be down, but it should work.
We use it as a vacuum pump on our main lines, so the application is a little different.
these are typically used in rv’s, and have to supply the water to a shower hear that is usually 6-8’ above the pump itself. If I was at the farm I would pull it out and test it but I have no idea when I’ll be back up there.

 

[M92PV4U]

Most people just hook them to the pool pump and let it do the work. You could probably fashion a hydraulic ram pump.

What size pipe do they normally use for the heating coil? I think ¾" x 1000' is too small for that long of a run. Although it was mentioned to run 2 ¾" x 500' parallel I think will work.

 

[The Beens]

As stated previously, you need to select a pump based on your Net Positive Suction/Pressure Head (NPSH or NPPH) depending on the location of the pump. If it is a "lift" pump like in a water well, its NPSH. If its a "pusher" pump like booster pump that fill water towers/elevated tanks, its NPPH. Most pump manufactures/sales men should be able to give you the pump curves for selecting a pump based on your need.

The NPS/PH is based on your Total Dynamic Head (TDH). This is calculated on the physical properties of your application. TDH = Elevation Head + Pressure Head + Friction Head.

• The elevation head is just the height from where your pump is located, I'm assuming you want it down next to the pool utilizing a lift pump, to the upper most point of where the water will travel. If the poly pipe is just going to be laying on top of the roof, for simplicity sake, just assume your elevation head is 9' if the pump is going to be on the deck.
• If one end of your pipe system is open, just drains out into the pool openly, then the pressure head is the difference in PSI from the point at the pump and the point at where the water pipe ties back in. If you leave the exit end open to the atmosphere, you can neglect pressure head in your TDH calculation because the pressure head would then just be the weight of the water in the pipe pushing back down on the pump and you've already accounted for that in your elevation head.
  • if you tie the exit end back into the pool under the surface water level of the pool. the pressure head = PSI at the pump + PSI at the line exit location (elevation difference between top of water level and the point of the pipe outlet multiplied by unit weight of water).
• The friction head is the total loss of flow, velocity, and pressure in the system due to friction. Friction in the pipe, friction at all the openings and fittings, etc..
  • adding a "Y" will not reduce the friction loss or the flow. Flow in into the system from the pump = flow out of the system (conservation of flow theory). Adding a "Y" fitting will increase friction loss and increase your TDH. Also, you would need to account for the location Y fitting back into your TDH equation for elevation head and pressure head.
  • Friction head = f * L/D * V^2/2*G
    • f = friction factor (just use .02) pretty universal, especially with poly pipe.
    • L = total length of pipe in feet
    • D = pipe diameter, also in feet
    • V = velocity of the water in the pipe. 3/4" dia. poly pipe will only flow so much. I don't know what it is off the top of my head, but your pump velocity will be the same, conservation of flow also includes velocity assuming pump outlet dia is also 3/4"
    • G = gravity. 32.2 ft/s/s
• Use the friction head posted previously, its close enough.

Your NPS/PH is gonna be somewhere around 17' assuming its 9-10' from the deck to the roof, 4 ish feet from the deck to the ground next to the pool and about 2-3' of friction loss head. TDH = 13' + 0 (using open outlet) + 2 or 3' Of course this is assuming the pump is on the ground at the base of the pool, its a 4' deep pool and your outlet is open and not under the surface level of the water. If you put the outlet under the water level, add about 8-10 to that TDH to account for the pressures at the pump and outlet.

Now the weight on the roof. The 200'ish pounds is pretty close figuring in the pipe too, maybe a little more. Don't know what 1000' of poly pipe weights, probably pretty east to find out. Just distribute the pipe out over the whole roof area. You'll probably have to do that anyway on account that you're gonna have a 1000' of it up there and you'll need as much pipe exposure to the sun as possible.

As far as using the heat of the sun with the black pipe and the reflection from the roof material to heat the pipe, this will work but you need to account for how long the water is in the pipe to soak up the heat. I have no idea how to calculate that heat transfer and contact time but I know it can be done. also, to increase or decrease the heat just add or remove pipe. Less/more heat is dictated by time in the pipe. Less pipe, less time, less heat. More pipe, more time, more heat.

If i were you, I'd hook my poly pipe straight into the pump line on the pool pump (between the pump and filter) and see if that doesn't get you where you want to be. Then you can decide if you want to chase the battery, solar charger and pump scenario.

 

[surpip]

wouldn't a solar cover work better, be less work and maybe cheaper?

 

[dntsdad]

Running off the pool pump isn't an option because I run the pool pump at night for 6 hours a shot in the summer because rates are WAY cheaper at night that during the day. Obviously at night, the poly pipe isn't going to get hot like during the day so its a waste of time.

On the solar pool cover, I have tried that before with poor results although I know some people they work great for. Also, I don't really want to put the thing on and take it off all the time.

The Beens.......most of what you wrote is over my head but I think I get enough out of it to be very useful.
Still not sure how to figure out the optimal GPM or GPH for the most bestest heat transfer from the pipe but I am going to try to find something on Google to read or a calculator if I can find one that I can understand

 

[not2hye]

Running off the pool pump isn't an option because I run the pool pump at night for 6 hours a shot in the summer because rates are WAY cheaper at night that during the day. Obviously at night, the poly pipe isn't going to get hot like during the day so its a waste of time.

On the solar pool cover, I have tried that before with poor results although I know some people they work great for. Also, I don't really want to put the thing on and take it off all the time.

The Beens.......most of what you wrote is over my head but I think I get enough out of it to be very useful.
Still not sure how to figure out the optimal GPM or GPH for the most bestest heat transfer from the pipe but I am going to try to find something on Google to read or a calculator if I can find one that I can understand

How light is the bottom of your pool? Mine is halfway to white from blue and the water is 80° this afternoon. A week of close to triple digit heat will have you swimming 24 hours a day.

 

[dntsdad]

How light is the bottom of your pool? Mine is halfway to white from blue and the water is 80° this afternoon. A week of close to triple digit heat will have you swimming 24 hours a day.

It use to get plenty warm but now the neighbor's trees have grown so tall that it gets very little sun in the late afternoon when its warmest outside. I am not sure of the temp but its too cold for the ballsack test most of the year.

I have been thinking of importing some bark beetles into them!! I hate those fucking trees. Messy as hell


Also, on the patio cover, I really am not concerned with weight. (6) 4x8 beams with 2" T&G top should hold way more than this will weigh without issue.

 

[M92PV4U]

It use to get plenty warm but now the neighbor's trees have grown so tall that it gets very little sun in the late afternoon when its warmest outside. I am not sure of the temp but its too cold for the ballsack test most of the year.

I have been thinking of importing some bark beetles into them!! I hate those fucking trees. Messy as hell


Also, on the patio cover, I really am not concerned with weight. (6) 4x8 beams with 2" T&G top should hold way more than this will weigh without issue.

Don't test the water just jump in.

 

[The Beens]

The Beens.......most of what you wrote is over my head but I think I get enough out of it to be very useful.
Still not sure how to figure out the optimal GPM or GPH for the most bestest heat transfer from the pipe but I am going to try to find something on Google to read or a calculator if I can find one that I can understand

If you can answer these questions, I can tell you your TDH fairly accurately. Well as accurate as your answers are anyway.

• Where is the pump going to be located....above the surface level of the water in the pool, at the surface level, or below?
  • if below, by how much?
    • how much higher is the roof than the pump?
  • if at, how deep is the suction hose into the pool and how long will the suction hose overall be?
  • if above, how high above, how long of a hose and how deep into the pool is it sticking?
• What is the inlet and outlet size of the pump?
• Will the return line into pool be above or below the water surface?
  • if below, by how much?

As far as the heat transfer goes, your going to have to take in some considerations and biggest one is the volume of your pool and how much of a temperature increase you want. If your pool is like mine, its 42" deep and the temperature at the surface is pretty close to the temperature at the bottom. They won't be the exact same but its close enough for ease of calculations. If your pool varies from 3' to 6 or 8', then you'll have a more dynamic change in temperature from top to bottom and you're average temp will need to increase more to get you where want to be than you would for a single depth pool.

My pool is about 13,500 gallons and in the prime of summer (southeast missouri) its about 80-85 on top and 75-80 at the bottom. Lets say i wanted raise it 5 degrees. For simplicity, the thought process would be that the water coming into the pool needs to be at or above the desired temperature. 1000' of black poly pipe sitting in the sun is gonna warm that water up A LOT! Especially if the flow is really low and the water has time to sit in the pipe.

1000' of 3/4" pipe will hold approximately 23 gallons total and 0.0229 gal/ft. A 12 volt pump probably wont have enough ass to lift or push the water up to the roof anyway but for educational purposes we'll continue. Most 12 volt pumps wont do much more than 7 (maybe 10 if you're lucky and you spend some coins) gallons per minute. So 0.0229 gal/ft X 1000 ft = 22.9 gal / 7 gal/minute = 3.27 minutes for one gal of water to go through the pipe. This means that every gallon of water flowing through the pipe will soak up heat for a little over 3 minutes. Not sure exactly how much heat it will pick up but anyone who's left a wrench out in the sun and then picked it back up will understand the concept. lol

Now back to the pool, again for simplicity sake we'll ignore some factors and assume that pumping your entire pool volume through the pipe once with a 3.27 minute contact time will be sufficient to get your desired temperature and we'll figure out how long it will take and we'll use my pool volume. 13,500 gallons / 7 gal/minute = 1928 minutes -> 32 hours. I'm pretty sure night will come at least once in that period of time and you'll lose all your heating and battery charging.

Couple of things to consider:

• The more the pump flows
  • the less time the water will soak in the pipe and sun, unless you add more pipe.
  • the faster the pool volume turns over (passes through the system)
• The less the pump flows
  • the more time the water will soak in the pipe and sun
  • the slower the pool volume turns over.

What are the chances that you can use a copper pipe coil over a back yard fire pit? If thats possible, you could just use the thermal cycle. One end of the coil connected to the deepest part of your pool and the other end about a foot below the surface. Build a fire and let the heat column warm the coil and it will thermal cycle the pool water without pumping (Swedish hot tub concept I think its called). Diameter of pipe and coil will dictate how much water can be moved in a given time. Of course you'd have to keep the fire burning all the frikin time though.

 

[The Beens]

Also, you can check how hot the water going through pipe will be if you already have the pipe. Measure the temperature and flow of water out of your outside faucet. Thermometer for the temp and a 5 gallon bucket and stopwatch for flow. See how long it takes to fill the bucket then divide 5 by the time it took, there's your GPM. Put the poly pipe on the deck in the sun at noon on a sunny day. hook the pipe to the faucet and turn it on. then go measure the temp of the water coming out. Let it run for a while and keep checking the temp coming out. That will tell you how much of a temperature increase your going to get at that specific GPM. Now go measure your pool temp and add the temperature change you measured from the pipe.

Now you'll know if you need a pump that does less than your faucet or more than your faucet. My money is going to be on less, but I don't know your water system. I could be wrong, you might have a really shitty water service.

 

[junkytj]

The Beens knows what he's talking about if you can understand what he's saying.

If you put a check valve on the outlet of your pump, it will hold enough water in your pipe that the pump should prime on it's own even if it isn't self priming.

Unless you are shooting for a specific flow rate, the velocity head or friction loss doesn't really matter. You need to be able to overcome your static head for startup, which won't be much with the check valve since your pipe will have enough water to siphon start the prime or at least help significantly. The pump will land on the curve where it lands once it starts, after it overcomes the startup, it will increase flow until it the flow is fast enough to create enough friction head to push back against it. This is the system curve that the pump is responding to.

I think your solar pump will work well. Find one that will push around 15' or 35 psi +/-. Solar pumps are a little different hooked directly to the panels. When the sun is full, they pump faster and when the sun is marginal, they pump slower. It does reduce the complexity of the electric side though. panel to pump and done. Check out agricultural sites for remote watering. Farmers do a good job of dumbing shit down for other farmers to understand. Definitely put a wye in to run the coils in parallel. You will slow down the water in both for heat transfer, reduce the linear feet the pump sees, and change the pool over faster.

 

[The Beens]

The Beens knows what he's talking about if you can understand what he's saying.

I have a hard time understanding what I'm saying half the time too.

If you put a check valve on the outlet of your pump, it will hold enough water in your pipe that the pump should prime on it's own even if it isn't self priming.

This, for sure. When you pick a pump, check the specs to see if it has an internal check valve.

Unless you are shooting for a specific flow rate, the velocity head or friction loss doesn't really matter. You need to be able to overcome your static head for startup, which won't be much with the check valve since your pipe will have enough water to siphon start the prime or at least help significantly. The pump will land on the curve where it lands once it starts, after it overcomes the startup, it will increase flow until it the flow is fast enough to create enough friction head to push back against it. This is the system curve that the pump is responding to.

There's a lot more friction head than you think, probably around 25% of the TDH, but you're right on the gravity suction helping over come that. You're right on the static head too, I doubt very seriously if there is a 12 volt pump out there that will overcome that. If there is, it will be expensive.

I think your solar pump will work well. Find one that will push around 15' or 35 psi +/-. Solar pumps are a little different hooked directly to the panels. When the sun is full, they pump faster and when the sun is marginal, they pump slower. It does reduce the complexity of the electric side though. panel to pump and done. Check out agricultural sites for remote watering. Farmers do a good job of dumbing shit down for other farmers to understand. Definitely put a wye in to run the coils in parallel. You will slow down the water in both for heat transfer, reduce the linear feet the pump sees, and change the pool over faster.

Yes to slowing down the water in each pipe and yes to increasing the heating time ONLY IF the amount of pipe is increased. I may have missed something in the original info, but if you wye the original 1000' of pipe to 2 paths of 500', you won't gain any heating time in the pipe. Halving the flow and halving the pipe length is a 1:1 ratio. Each run of pipe would need to be longer than 500' to gain any heating time.

No to the changing the pool volume over faster with the wye set up. Flow into the system is flow out of the system. Doesn't matter how many times you split the pipe up after the pump, the pump flow will dictate the system flow. The only way the system flow could increase beyond the ability of the pump is if the gravity end overcomes the pump. Don't know if that is possible in any of these scenarios though. The gravity will probably be only enough to overcome the friction loss and some of the static head.

 

[dntsdad]

Also, you can check how hot the water going through pipe will be if you already have the pipe. Measure the temperature and flow of water out of your outside faucet. Thermometer for the temp and a 5 gallon bucket and stopwatch for flow. See how long it takes to fill the bucket then divide 5 by the time it took, there's your GPM. Put the poly pipe on the deck in the sun at noon on a sunny day. hook the pipe to the faucet and turn it on. then go measure the temp of the water coming out. Let it run for a while and keep checking the temp coming out. That will tell you how much of a temperature increase your going to get at that specific GPM. Now go measure your pool temp and add the temperature change you measured from the pipe.

Now you'll know if you need a pump that does less than your faucet or more than your faucet. My money is going to be on less, but I don't know your water system. I could be wrong, you might have a really shitty water service.

This is such a great idea that I would have never thought of it!!!

I have been thinking about just getting the most GPH 12v pump I can find, which so far is 7 and I can always put a T valve on the return right at the pool water to restrict the flow and slow it down to what I find is the best rate for heat transfer. Not sure on if a restriction on the end would reek havoc on everything though.

 

[dave_dj1]

What size pipe do they normally use for the heating coil? I think ¾" x 1000' is too small for that long of a run. Although it was mentioned to run 2 ¾" x 500' parallel I think will work.

Ones I have seen were 1.5" , probably not that much pipe though, maybe a 100'

 

[The Beens]

Ever consider using a hand full of these?

https://www.thepondguy.com/product/k...4aAsEIEALw_wcB

Probably have more luck getting the temperature change your looking for in a shorter amount of time. Not sure about the whole HF Battery and solar charger system keeping up with the draw from these things though. There's probably a 90 year old slide rule that will tell you exactly what wire, AC/DC cd or converter to use and how big a batter(ies) you'll need for all that electrical hocus pocus.

 

[junkytj]

I have a hard time understanding what I'm saying half the time too.

This, for sure. When you pick a pump, check the specs to see if it has an internal check valve.

There's a lot more friction head than you think, probably around 25% of the TDH, but you're right on the gravity suction helping over come that. You're right on the static head too, I doubt very seriously if there is a 12 volt pump out there that will overcome that. If there is, it will be expensive.

Yes to slowing down the water in each pipe and yes to increasing the heating time ONLY IF the amount of pipe is increased. I may have missed something in the original info, but if you wye the original 1000' of pipe to 2 paths of 500', you won't gain any heating time in the pipe. Halving the flow and halving the pipe length is a 1:1 ratio. Each run of pipe would need to be longer than 500' to gain any heating time.

I didn't say that exactly right. Not increase heating time, heating efficiency. Each individual pipe will be more efficient at exchanging heat. Less total water will go through each individual pipe. The water at the end of the shorter pipe will have absorbed less heat than the water at the end of the longer pipe. Greater delta T means more transfer. It becomes more efficient at transfer. I'm not a thermodynamics guy, sorry for the poor description.

No to the changing the pool volume over faster with the wye set up. Flow into the system is flow out of the system. Doesn't matter how many times you split the pipe up after the pump, the pump flow will dictate the system flow. The only way the system flow could increase beyond the ability of the pump is if the gravity end overcomes the pump. Don't know if that is possible in any of these scenarios though. The gravity will probably be only enough to overcome the friction loss and some of the static head.

Yes it will. You reduce Hv by the parallel flowpaths with lower Hv the flow increases in the system to match the pump. If flow increases, you change over the pool faster. If your theory were correct, I could supply a whole town with 2" PVC and change the pump if I wanted more flow. Instead, I increase pipe diameter and loop flow paths to feed from 2 directions to increase fireflow with the same pumps/head pressure plane

 

[The Beens]

I didn't say that exactly right. Not increase heating time, heating efficiency. Each individual pipe will be more efficient at exchanging heat. Less total water will go through each individual pipe. The water at the end of the shorter pipe will have absorbed less heat than the water at the end of the longer pipe. Greater delta T means more transfer. It becomes more efficient at transfer. I'm not a thermodynamics guy, sorry for the poor description.

No, I'm agreeing with you. I was just saying that if 1000' is all he has to work with, then adding a wye will be a wash as far as getting the change in Temperature if the two runs of pipe are just a half split of the original 1000'.

Yes it will. No it won't.

You reduce Hv by the parallel flowpaths with lower Hv the flow increases in the system to match the pump. <- Exactly, the flow through the pipe or total combined flow through each pipe will never be greater than what the pump will allow. If 7 gpm is all your pump will flow then 7 gpm is all your going to get out the other end of the pipe.

If flow increases, you change over the pool faster. Like you said above, the system will match the pump. The pump flow will not increase, so the system flow will not increase. Adding a wye doesn't change the amount of flow coming from the pump. It will just reduce the flow coming out the end of each pipe, and if you add those flow measurements together....its still gonna be at or below the available pump flow.

If your theory were correct, I could supply a whole town with 2" PVC and change the pump if I wanted more flow. Instead, I increase pipe diameter and loop flow paths to feed from 2 directions to increase fireflow with the same pumps/head pressure plane. Now you are just being silly. You're comparing a closed loop pressurized system to an open ended parallel flow system that isn't gonna see flows or velocity's that would rival a garden hose. Also, you're familiar with Velocity Head, then you are also familiar with laminar and turbulent flow. If you are, then you know as well as I do that a 2" pipe will only flow so much before the flow inside the pipe becomes turbulent and you start losing system flow. Your assertion that my theory is incorrect based your imagined example is unfounded and you know it.

Further more...your fire flow sample based on a loop feeding from two directions is not even remotely applicable to the scenario of circulating water through a heat source for the purpose of raising a swimming pool to above "Nut sack shivver" temperatures. Loops are placed in water service systems to allow maximum "available" flow at any given point along that loop.

 

[junkytj]

Don't make me post up a parallel flow calculation vs a single pipe system using the same pump and pipe diameters. The pump will land on the system flow where it lands, but we will have reduced head. You have looked at enough pump curves to know what happens there. Short of a electro/mechanical regulated PD pump you are dead wrong on flow in a single line vs flow in a parallel line with equal lengths of pipe and diameter and n value. Municipal systems are not closed loop BTW. Elevated tanks are always vented to atmosphere. I'm very familiar with manning's equation, laminar and turbulant flow, k values of valves, Bernoulli.

Parallel system = Q=A1V1+A2V2
H1=H2


In our case, the two legs are the same, so H1=H2 convenient as it allows us to say V1 and V2 are the same

Assume 10CFS and solve for V
use .75'=D=.44 ftft
10 ftftft/sec=.44ftftV+.44ftftV
10ftftft/sec=.88ftftV
11.4ft/sec=V

Single system Q = A1V1

Same Q as you say
10ftftft/sec=.44ftftV
22.7ft/sec=V

Now do I really need to run through V with a random pump curve to show you what happens when water is going twice as fast through a pipe and what that does to a system curve also or can you take it from here?

 

[dntsdad]

Crayons please!!

I have no idea what the fuck you guys are even talking about anymore. Is that shit English?

 

[The Beens]

Don't make me post up a parallel flow calculation vs a single pipe system using the same pump and pipe diameters. The pump will land on the system flow where it lands, but we will have reduced head. You have looked at enough pump curves to know what happens there. Short of a electro/mechanical regulated PD pump you are dead wrong on flow in a single line vs flow in a parallel line with equal lengths of pipe and diameter and n value. Municipal systems are not closed loop BTW. Elevated tanks are always vented to atmosphere. I'm very familiar with manning's equation, laminar and turbulant flow, k values of valves, Bernoulli.

Parallel system = Q=A1V1+A2V2
H1=H2


In our case, the two legs are the same, so H1=H2 convenient as it allows us to say V1 and V2 are the same

Assume 10CFS and solve for V
use .75'=D=.44 ftft
10 ftftft/sec=.44ftftV+.44ftftV
10ftftft/sec=.88ftftV
11.4ft/sec=V

Single system Q = A1V1

Same Q as you say
10ftftft/sec=.44ftftV
22.7ft/sec=V

Now do I really need to run through V with a random pump curve to show you what happens when water is going twice as fast through a pipe and what that does to a system curve also or can you take it from here?

Alright, we are coming at this from two different directions. You've done a lovely bunch of algebra up there and you are describing the speed at which the water will travel through the pipe and how the speed is different in a single pipe flow vs a parallel pipe flow. I'm not disagreeing with any of that and based on your equation Q=A1V1 + A2V2 = 10cfs = AsVs you agree that no matter how many times you have VA on one side of the equals sign, it will always equal the corresponding Q.

Velocity and (wet) area will change, in fact they have to change in order to compensate for maintaining the flow. "Bernoulli 3:16"

I'm simply saying that splitting the pipe once, twice, three times or 100 hundred times after the pump will not reduce the total amount of time it will take to pump the entire pool volume back into itself based on OP's original call out...1 pump into 2 runs of 3/4" pipe at 500' long each.

Now, I don't really know what we are arguing about here but if you scroll back up through my comments, I'm pretty sure I've agreed with you on...well... damn near everything you've said. Except for the time in which it will take to change over the pool volume and the time the water will spend in the pipe (single vs parallel) based on flow of each pipe.

How long does it take to change the water over in a 1,000 ft^3 pool

Parallel System

Time = volume / flow
T = V / (Q1+Q2)
T = 1000ft^3 / (V1A1 + V2A2)
T = 1000 / (11.4*.44 + 11.4*.44)
T = 1000ft^3 / 10 ft^3/s
T = 100 seconds

Single System
T = V / (Q1)
T = 1000ft^3 / (V1A1)
T = 1000 / (22.7*.44)
T = 1000ft^3 / 10 ft^3/s
T = 100 seconds

^^ standard equations using your values and theory, still results in my comment that it will not increase the speed at which the pool volume turns over.


How much time will the water spend in the pipe?

Time = Length / Velocity

Parallel System
T = 500' / 11.4ft/s
T = 43.9 seconds

Single System
T = 1000' / 22.7ft/s
T = 44.1 seconds

^^ I think we can agree that they are equal.

 

[junkytj]

Alright, we are coming at this from two different directions. You've done a lovely bunch of algebra up there and you are describing the speed at which the water will travel through the pipe and how the speed is different in a single pipe flow vs a parallel pipe flow. I'm not disagreeing with any of that and based on your equation Q=A1V1 + A2V2 = 10cfs = AsVs you agree that no matter how many times you have VA on one side of the equals sign, it will always equal the corresponding Q.

Velocity and (wet) area will change, in fact they have to change in order to compensate for maintaining the flow. "Bernoulli 3:16"

I'm simply saying that splitting the pipe once, twice, three times or 100 hundred times after the pump will not reduce the total amount of time it will take to pump the entire pool volume back into itself based on OP's original call out...1 pump into 2 runs of 3/4" pipe at 500' long each.

Now, I don't really know what we are arguing about here but if you scroll back up through my comments, I'm pretty sure I've agreed with you on...well... damn near everything you've said. Except for the time in which it will take to change over the pool volume and the time the water will spend in the pipe (single vs parallel) based on flow of each pipe.

How long does it take to change the water over in a 1,000 ft^3 pool

Parallel System

Time = volume / flow
T = V / (Q1+Q2)
T = 1000ft^3 / (V1A1 + V2A2)
T = 1000 / (11.4*.44 + 11.4*.44)
T = 1000ft^3 / 10 ft^3/s
T = 100 seconds

Single System
T = V / (Q1)
T = 1000ft^3 / (V1A1)
T = 1000 / (22.7*.44)
T = 1000ft^3 / 10 ft^3/s
T = 100 seconds

^^ standard equations using your values and theory, still results in my comment that it will not increase the speed at which the pool volume turns over.


How much time will the water spend in the pipe?

Time = Length / Velocity

Parallel System
T = 500' / 11.4ft/s
T = 43.9 seconds

Single System
T = 1000' / 22.7ft/s
T = 44.1 seconds

^^ I think we can agree that they are equal.

We're arguing because you can't seem to understand that on any non pd pump, the Q reduces as head increases and head increases as velocity increases. On that cute little Bernoulli equation, you'll note that velocity is squared. Go back to your cute calculus and think about why that is. If velocity is decreased in the parallel system as we both now have proven it is, then friction decreases as every text book written since calculus was invented will show, then Q increases. What happens to the water in pool if Q increases? It changes over more often.

 

[dntsdad]

Finally had some time to get this going

Using a 12v pump right now rated at 8 amps, a 35aH Gel battery, and a small 2/10amp trickle charger on auto to keep the battery up.

This was the water temp on Saturday. It was not all the hot here on Saturday. I'd guess about 80ish when I tested this





This is on Saturday coming out of the return to the pool.
Now that 110 had been sitting in the tubing for a while so it was really hot and actually measured it at 119 before I grabbed my phone to take a pic.






Today I turned the pump on at about 10am this morning. Cool outside. It was probably about 80ish.

Water temp from my floating shark thermometer.


At about 1:10pm I took the return and filled a 5 gallon bucket with the return line.

It took 160 seconds to fill the bucket as I have a ball valve on the return to reduce the flow if I want. I am just starting to play with different rates for different results.

This was in the bucket. Again, after running non-stop for about 3 hours so standing water in the tubing is LONG gone and this would be a continuous result


About 108 or so.

So, if my math is correct, that is about 2GPM. Even though the temp is good on the return, I am not sure that rate will make any difference in a 25k gallon pool.

I am going to increase the flow and see how the results change. The ball valve is about 30% open Id guess right now

It is suppose to heat up over the weekend into the 105-107 range outside so I am kind of looking forward how this does.

I also order a couple more pumps to experiment with. A 110 version of the same pump I have with a lower flow rate. It states a 5min on / 10 min off duty cycle which wasnt in the specs when I ordered it so that probably isn't going to work. I also ordered a submersible pump that had a head claim of 12ft so we will see. I have a submersible here that is new that had a head claim or 9ft and it wouldn't make it up the vertical climb to the top of the patio cover

 

[dntsdad]

Also, here is how it is setup on the roof. I obviously made the UFO Landing platform way too big but I wanted to make it larger so I can add more tubing down the line if I want too.

From the ground

I tried like hell to just uncoil it on the roof and start my spirals.. Hell no, shit kinked like crazy so I finally got pissed and dropped it off the front of the house and walked it down the street to uncoil it. Yep, every damn neighbor had to come out to see what the hell I was doing! That is my house WAY DOWN THERE at the arrow!

 

[The Beens]

So, if my math is correct, that is about 2GPM. Even though the temp is good on the return, I am not sure that rate will make any difference in a 25k gallon pool.

I am going to increase the flow and see how the results change. The ball valve is about 30% open Id guess right now

It is suppose to heat up over the weekend into the 105-107 range outside so I am kind of looking forward how this does.

I also order a couple more pumps to experiment with. A 110 version of the same pump I have with a lower flow rate. It states a 5min on / 10 min off duty cycle which wasnt in the specs when I ordered it so that probably isn't going to work. I also ordered a submersible pump that had a head claim of 12ft so we will see. I have a submersible here that is new that had a head claim or 9ft and it wouldn't make it up the vertical climb to the top of the patio cover

Your math is close enough, just be sure to account for velocity or you'll hurt junky's feelings.

As far as making a difference on the entire pool volume, not even remotely. At 2gpm, it'll take you over a week (8.5 days, give or take) to completely turn the pool over and you'll need insulation during the night or you'll lose your temp change progress. That's why I asked about plumbing into your actual pool pump. If you assume that there are 8 prime heating hours in a day and the heat exchange in the pipe is linear over those 8 hours and instantaneous, it wont be but still, you would need a pump that does 480 gpm. Which is probably what your pool filtration pump is close too. I think they are set up to turn the pool over 2 or 3 times in a 24 hour period.

I think the best case scenario with the pumps and set up you are envisioning is only gonna raise the temperature of the top 6-12" of water a few degrees. You may have better luck reducing the sack shiver factor by icing your goods with whatever you're going to have for dinner before you get in the pool.

 

[The Beens]

On your pipe set up, it looks like you wye'd the pipe on the roof coming into the circle and then collected it back into a single line coming back down. Pull your return line up out of the pool so it only hangs over the pool edge. If you pump your warm water down the bottom of the pool, you'll lose your heating as the water passes through the colder water on the bottom and rises back to the surface.

If you use a non-submersible pump, shorten your inlet line so that you're only picking up the top 12" of water. Same thing if you use the submersible, hang it off the pool edge so its only about 12" or so from the water surface to the inlet. That way your static head is reduced.

 

[Aisin]

My pool is 76/77 degrees right now. In the afternoon it gets to around 82/83 degrees. Average temps have been around 100. Last week there were a few days where the water got up to about 86/87. It was around 106 for those couple days.

 

[dntsdad]

On your pipe set up, it looks like you wye'd the pipe on the roof coming into the circle and then collected it back into a single line coming back down. Pull your return line up out of the pool so it only hangs over the pool edge. If you pump your warm water down the bottom of the pool, you'll lose your heating as the water passes through the colder water on the bottom and rises back to the surface.

If you use a non-submersible pump, shorten your inlet line so that you're only picking up the top 12" of water. Same thing if you use the submersible, hang it off the pool edge so its only about 12" or so from the water surface to the inlet. That way your static head is reduced.

This is how I have it setup.

I like the sound of the water hitting the pool for one and i figured having the return out of the water would reduce backpressure as well. I don't know if that is true but it can't hurt.

Not really liking this 110 pump. the submersible comes today and I hoping that is going to work better for flow and it being able to run continuously will be better than this 110 pump that gets hot as fuck. Also, the pressure switch is just a pain the ass to deal with all the cycling which probably contributes to the heat wash

 

[dntsdad]

My pool is 76/77 degrees right now. In the afternoon it gets to around 82/83 degrees. Average temps have been around 100. Last week there were a few days where the water got up to about 86/87. It was around 106 for those couple days.

Mine use to get really warm. Like I would put the hose in it to cool it down because it wasn't refreshing. Now the neighbors trees block most all of the direct sun after about 200 on a summer day.

Bigly difference