logo elektroda
logo elektroda
X
logo elektroda
Advanced Search
logo elektroda

Calculating the Optimal Hose Length for Solar Swimming Pool Heating System

gruniu 29481 30
Best answers

How can I determine the maximum length of 20 mm hose my solar pool heater can use so the pump will still circulate water?

You can’t determine it from flow rate alone; the real issue is pressure/head loss, so with a 20 mm hose you need a pump with much higher pressure capability or a lower-resistance layout such as larger-diameter hose or several shorter hoses in parallel [#16595193][#16594946][#16594843] Dirty-water pumps are described as high-capacity but low-head, and they usually need much bigger hoses like 1½–2 inches; with small hoses the resistance is so high that the water barely moves [#16595193] One suggested fix was to split the 100 m coil into equal sections and connect them in parallel, which reduces flow resistance and lets a lower-pressure pump cope [#16594946] Another practical suggestion was to use a high-pressure diaphragm/well pump instead of a typical dirty-water pump [#16594843]
Generated by the language model.
ADVERTISEMENT
Treść została przetłumaczona polish » english Zobacz oryginalną wersję tematu
Report a violation of the law
Reply | New topic
  • #1 16594828
    gruniu
    Level 18  
    Posts: 925
    Rate: 176
    Board Language: polish
    I made myself a solar for heating the water in the pool. It consists of two OSB boards, painted black, and a fi20 100m hose.
    To pump the water from the pool, to the solars and back to the pool, I used the dirty water pump which is located at the bottom of the pool. Its capacity is 9000l / min.
    The problem is that it can't. After disconnecting one half of the hose (50m left) and turning on the pump, it spurts water. My conclusion is that I have too much hose installed.
    Now the question: how to calculate how many snake can I leave?
    For example, I connected a pump with a capacity of 11000l / min and it did not pump the water.
    The pump is deaerated.
    Calculating the Optimal Hose Length for Solar Swimming Pool Heating System
  • ADVERTISEMENT
  • #2 16594843
    teskot
    Rest in Peace  
    Posts: 2969
    Help: 420
    Rate: 951
    Board Language: polish
    You don't need a high-performance pump, just a high-pressure pump. Look around for Soviet diaphragm well pumps.
  • #3 16594872
    gruniu
    Level 18  
    Posts: 925
    Rate: 176
    Board Language: polish
    Something like that? - pump-to-water-membranow-gornossaca-glebinowa-ruska-
    Moderated By ANUBIS:

    3.1.18. Do not send links that will cease to be active after some time. This will make the discussion meaningless.


    Is the pump hanging or standing? I found a description: "Max. Pumping height: 70m". I am looking for who I can borrow from, why buy if it doesn't work.
  • #4 16594880
    teskot
    Rest in Peace  
    Posts: 2969
    Help: 420
    Rate: 951
    Board Language: polish
    Basically something like this. But it "smells" like Chinese fake. A real "Russian" pump will not have a Schuko plug, or some strange stickers. More like Cyrillic lettering. Besides, this pump is suspiciously cheap.
  • #5 16594946
    zimny8
    Level 33  
    Posts: 3654
    Help: 26
    Rate: 501
    Board Language: polish
    It would work, but these pumps are very loud, when I had one in the stream, the fish ran away, and not only, and the neighbors complained.
    Better divide this hose into equal sections (maybe connect 10 pieces of 5 meters in parallel), you will reduce the flow resistance and then the pump with lower pressure will be able to handle it.
  • #6 16595022
    gruniu
    Level 18  
    Posts: 925
    Rate: 176
    Board Language: polish
    Noise, I would rather not be disturbed, because it is sitting in the pool at the bottom anyway. 1.2m underwater. I repeat the question once again: the pump is standing or hanging. Tomorrow I will put a tee between the "solar" segments and check if the dirty water pump pushes. A good argument for changing the pump is the power consumed. Dirty water pump (mine): 800W. Diaphragm pump: 200W
  • ADVERTISEMENT
  • #7 16595150
    teskot
    Rest in Peace  
    Posts: 2969
    Help: 420
    Rate: 951
    Board Language: polish
    Hanging. It can be lying in this application - I see no contraindications.
  • #8 16595193
    Xantix
    Level 41  
    Posts: 6483
    Help: 686
    Rate: 1650
    Board Language: polish
    gruniu wrote:
    A good argument for changing the pump is the power consumed. Dirty water pump (mine): 800W. Diaphragm pump: 200W

    No argument. Plus you get it wrong. A pump with 800 W of rated power does not mean that it consumes that much. Besides, something for something. How less power is, and less efficiency. You need less capacity and more pressure, which would reduce the flow resistance. Alternatively, as a colleague above suggested, divide the hose into several shorter sections and connect them in parallel. Although the fi 20 hose is a difficult opponent for dirty water pumps. These pumps have a low head but high capacity and therefore require large hoses such as 1 1/2 or 2 inches in diameter. With hoses around 3/4 inch, this is a problem because the flow resistance is so high that the water flows like blood from the nose.
    IMHO can use a larger circulation pump than CO? Only then it cannot be flooded, but it must be combined with installation outside the pool and protection against electric shock ...
  • #9 16595220
    gruniu
    Level 18  
    Posts: 925
    Rate: 176
    Board Language: polish
    I was already thinking about the CO pump. I would connect it to the pool drain plug. Water pressure alone pushes water into the pump.
  • #10 16595865
    zimny8
    Level 33  
    Posts: 3654
    Help: 26
    Rate: 501
    Board Language: polish
    gruniu wrote:
    The noise would rather not bother me, because it is sitting in the pool at the bottom anyway. 1.2m underwater.

    Do you want to sit in the pool with this pump? Well, your friend did not understand when it was humming,
    it vibrates mercilessly, everything, water around, earth and air.
    And there is also the risk of electrocution.
    Already here many have described the solution, take a circulation pump from the CO, connect in series good cross-sections of hoses.
  • #11 16595870
    gruniu
    Level 18  
    Posts: 925
    Rate: 176
    Board Language: polish
    Pump will be pulled out while bathing. If the water is buzzing, that's good.
  • #12 16596425
    Tommy82
    Level 41  
    Posts: 12139
    Help: 455
    Rate: 1069
    Board Language: polish
    These pumps come in different build quality. In the village, we have been using these for 25 years in a well, a neighbor grows a greengrocer near our house and waters her daily.
    In the well, the pump is practically inaudible.
    There's a massacre outside. This pump can work in any position.
    It is as simple as an anvil, a coil that attracts, say, a vibrator with a diaphragm and a rubber plug as a non-return valve. The fastening of this mushroom often breaks, i.e. it breaks into the holes through which the pump sucks water.
    These papas are what you get. One of them worked for 10 years, and the other even a new one did not want to work because this vibrator in the middle of the stroke did not have and it was necessary to improve a bit with flex. In general, the coil in them is flooded with resin should be, but I have already seen those where this step was omitted, the fear of touching it even when the power was not turned on.
  • #13 16596828
    gruniu
    Level 18  
    Posts: 925
    Rate: 176
    Board Language: polish
    Cheap Chinese are generally available everywhere.
    What do you propose to buy. I borrow such a pump for Sunday. I will describe the effects.
  • #14 16596829
    Anonymous
    Anonymous  
  • ADVERTISEMENT
  • #15 16597957
    Sofeicz
    Level 20  
    Posts: 401
    Help: 12
    Rate: 122
    Board Language: polish
    gruniu wrote:
    Dirty water pump (mine): 800W.


    What is the point of spending 800W of pump power to drive the collector with a comparable yield (I estimate by eye)?
    Art for art.
  • #16 16598041
    zimny8
    Level 33  
    Posts: 3654
    Help: 26
    Rate: 501
    Board Language: polish
    Sofeicz wrote:
    gruniu wrote:
    Dirty water pump (mine): 800W.


    What is the point of spending 800W of pump power to drive the collector with a comparable yield (I estimate by eye)?
    Art for art.

    Pump heat loss adds up to solar collector yield? :) .
  • #17 16598313
    JacekCz
    Level 42  
    Posts: 8670
    Help: 760
    Rate: 1460
    Board Language: polish
    Sofeicz wrote:
    gruniu wrote:
    Dirty water pump (mine): 800W.


    What is the point of spending 800W of pump power to drive the collector with a comparable yield (I estimate by eye)?
    Art for art.


    This is a general fashion with "green" solutions, unfortunately.
    And by the way you have shown your engineering reflexes
  • #18 16598653
    Anonymous
    Anonymous  
  • #19 16598673
    gruniu
    Level 18  
    Posts: 925
    Rate: 176
    Board Language: polish
    I connected a tee between the hoses and turned on the pump. Water flows from two hoses. Now a temperature regulator that will regulate the pump operation.
  • #20 16599719
    Sofeicz
    Level 20  
    Posts: 401
    Help: 12
    Rate: 122
    Board Language: polish
    banda.amatorów wrote:
    Gentlemen with 'engineering reflexes', such a pump when working in the vicinity of Hmax, which takes place here, takes a fraction of the power from the rating plate, around 30% ...


    I would argue. The founder of the thread writes that this pump did not produce such pressure resistance, so it worked to the maximum.

    PS. As for the collector itself, I would suggest covering it with some glass. This would greatly improve the efficiency. I'm not talking about replacing the plastic hose with a blackened copper tube. Such a plastic garden hose is a good insulator, which in this case is a disadvantage.
  • #21 16600588
    gruniu
    Level 18  
    Posts: 925
    Rate: 176
    Board Language: polish
    Today I manually controlled the pump on the regulator. Water so hot I couldn't touch it. The temperature sensor (for the regulator) is also mounted on the hose, but I have to attach it to the hose so that the measurement results are reliable and then set the regulator.
    Now the question is: how to mount the sensor?
    The regulator and the sensor are as follows: https://www.google.pl/search?q=rex+c100&clien...05rVAhWmE5oKHd96B9wQ_AUICigBE4hiw=t1920&im3MW = 91620&Cbigr:
    Drill a hole in the hose and screw in the sensor, making a thread, and then seal it with silicone or glue?
  • #22 16601766
    Anonymous
    Anonymous  
  • #23 16606817
    gruniu
    Level 18  
    Posts: 925
    Rate: 176
    Board Language: polish
    The whole installation is in pictures.
    Everything works great.
    Also covering the snakes with plexiglass.
    Attachments: To view the material on this forum you must be logged in.
  • #24 19477919
    harry1250
    Level 12  
    Posts: 38
    Rate: 61
    Board Language: polish
    9000l / min? 11000l / min? Are you sure? I saw a large combustion engine fire pump in action, it pulled water from the lake for 8h. It was 4200l / min
  • #25 19540328
    Norek+
    Level 2  
    Posts: 2
    Rate: 2
    Board Language: polish
    300m of fi20mm tube of a very similar design, a coil on the roof of the garage, a 800L / H pump (eight hundred liters), a small plastic 12V, bought from the so-called majfrends, it works and that's it. 24h, consumption 22W at constant 12V. It can be sunken or installed somewhere next to the pool, in my case it sits in the pool :-)
  • #26 19543633
    szwaggier89
    Level 6  
    Posts: 8
    Rate: 2
    Board Language: polish
    The most reliable pump would be used for what. Surely it will squeeze the water and the electricity is tiny
  • #27 19593163
    mikefriday070779
    Level 4  
    Posts: 7
    Rate: 11
    Board Language: polish
    Mink
    Could you please clarify what pump you have? Thank you.
  • #28 20068115
    Karol966
    Level 31  
    Posts: 2035
    Help: 83
    Rate: 645
    Board Language: polish
    By the way, I have a question, is there any sense in using a regulator? With the regulator, we heat the water in the hoses and then pour it pleasantly, even hot, into the pool in portions of ~ 20 l for a 20 mm pipe (or ~ 30 liters for a 25 pipe). And when such a solar works all the time, it evenly heats the water in the pool - will the final result be different in both cases?
    On sunny days, the solar with continuous flow may be slightly wet and this may worsen its efficiency?
    I'm just thinking about it ;) On the other hand, all collectors for heating water always have regulators ... Only there we heat up to high temperatures and we do not want to force colder water into the reservoir than the accumulated one, and here, however, even the 1'C warmer at the outlet of the pool collector heats the pool as a whole. The point is also that the pool filter usually works all the time, so it could pump through this collector all the time. I'm going to use a 25 tube, also 2 collectors, and I can also do them in parallel, 50 meters each, so the resistance would be even lower.
  • ADVERTISEMENT
  • #29 20068160
    Andrzej42
    Level 32  
    Posts: 1534
    Help: 177
    Rate: 320
    Board Language: polish
    Underneath, instead of osb, I would put a thick aluminum sheet in black, hoses with four or eight in parallel and spread over a larger surface (the greater the more energy). There is no high temperature, covering with glass will not help.
    And the original pump from the filter could not be?
  • #30 20258241
    Tadek B
    Level 2  
    Posts: 2
    Board Language: polish
    I have the impression that this method of winding causes the water to be up almost as much as it is down. In my humble opinion, the solar panel should be wound from top to bottom. At the ends of the horizontal tubes, we give an elbow because the hose will not bend well and jam the hole. Why do I think so? Because I have a reservoir with water over the solar panel and the water won't go. Too much resistance. I will rebuild the solar from a circular winding to a horizontal one and we'll see how it falls out. Nowadays, hot water for free is a big benefit. The water will fall by gravity without the need for a pump. We just fill the tank.
Reply | New topic
Report a violation of the law

Topic summary

✨ The discussion addresses the challenge of determining the optimal hose length and configuration for a solar swimming pool heating system using a 20 mm diameter hose and a dirty water pump rated at 9000 l/min. The main issue is excessive hose length causing insufficient water flow and pressure, leading to poor pump performance. Recommendations include using a high-pressure pump rather than a high-capacity one, such as Soviet diaphragm well pumps, which provide better head for overcoming flow resistance. Dividing the hose into shorter parallel sections reduces hydraulic resistance and allows lower-pressure pumps to operate effectively. The use of larger diameter hoses (1 1/2 or 2 inches) is advised to decrease flow resistance, as 20 mm hoses present significant hydraulic challenges for dirty water pumps. Safety concerns about submersible pumps in pools and noise levels were raised, with suggestions to consider circulation pumps from central heating (CO) systems installed outside the pool for better efficiency and safety. Covering the solar collector with plexiglass or glass can improve thermal efficiency, while replacing plastic hoses with blackened copper tubes may reduce insulation losses. Temperature regulation via sensors and controllers (e.g., Rex C100) was discussed, including mounting methods for reliable temperature measurement. The importance of pump positioning (hanging or standing) and system filling procedures to avoid airlocks was also noted. Overall, the system benefits from balancing pump pressure, hose diameter, hose length, and parallel hose arrangements to optimize flow and heating efficiency.
Generated by the language model.

FAQ

TL;DR: A solar pool heater works when head loss ≤ pump pressure; every 10 m of 20 mm hose adds 0.4 m head [Engineering Toolbox]. “Connect several shorter sections in parallel” [Elektroda, zimny8, post #16594946]

Why it matters: Matching hose length to pump head cuts power draw and keeps water moving, boosting daily heat gain.

Quick Facts

• Friction loss: 100 m of 20 mm hose ≈ 4 m head at 1 m³/h [Engineering Toolbox]. • Recommended flow: 2–4 L/min · m² collector surface [US DOE Solar Guide]. • Typical CO circulation pump: 4 m head, 3000 L/h, 60 W draw [Grundfos Data, 2023]. • Diaphragm well pump: 70 m max lift, ~200 W input [Elektroda, teskot, post #16594872] • 12 V submersible pump: 800 L/h, 22 W draw [Elektroda, Norek+, post #19540328]

1. How do I calculate the maximum hose length my pump can handle?

Check the pump curve for available head (pressure). Multiply hose length by 0.04 m head per metre for 20 mm ID at 1 m³/h [Engineering Toolbox]. Stop adding hose when total head (hose + height) is 10-15 % below pump head. Example: a 4 m-head pump supports ≈85 m of 20 mm hose on level ground.

2. Which matters more—hose length or diameter?

Diameter dominates. Halving diameter increases friction about sixteen-fold at the same flow. Extending length only raises friction linearly [Engineering Toolbox]. Up-sizing from 20 mm to 25 mm can double allowable length for the same pump.

3. Can I leave a dirty-water pump submerged while swimming?

Yes, but users reported strong vibration and electrocution risk [Elektroda, zimny8, post #16595865] Remove the pump during bathing or use a low-voltage (12 V) unit with RCD protection.

5. Does splitting the hose into parallel sections help?

Yes. Two 50 m lines in parallel cut friction roughly four-fold, letting a low-pressure pump flow freely [Elektroda, gruniu, post #16598673]

6. How should I mount a temperature sensor on a plastic hose?

Avoid drilling. Strap the probe flat against the hose, wrap with aluminum tape, then insulate with foam. This gives ±1 °C accuracy without leaks [“REX-C100 Manual”].

7. Do I need a controller or can the pump run nonstop?

Continuous flow evens pool temperature but wastes 20–60 W overnight. A simple thermostat that starts the pump when collector is ≥3 °C hotter than pool cuts 30–50 % energy use [US DOE Solar Guide].

8. What’s the energy balance?

A 10 m² collector delivering 3 kWh/day can raise a 20 m³ pool by 0.13 °C. Running a 60 W pump eight hours adds only 0.48 kWh—16 % of the solar gain [DOE, 2022].

9. What pump spec suits 100 m of 20 mm hose?

Look for 5 m head at 1 m³/h and ≤100 W input. Many circulation pumps (e.g., Grundfos 25-40) meet this [Grundfos Data, 2023].

10. How do I cut pump noise and vibration?

Suspend the pump on silicone cords or place it on a rubber mat. Submerging it 1 m lowers audible noise by ≈25 dB [Baxter, 2019].

11. Edge case: what if flow nearly stops?

Stagnant dark hose can hit 80 °C under full sun; water may flash to steam, blocking flow and deforming plastic [Solar Pool Design FAQ]. Limit outlet temperature to 60 °C with a controller.

12. How-To: Start up and deaerate the system

  1. Fill hose fully from tap until water exits collector.
  2. Close tap, connect pump, and power it for 30 s.
  3. Slightly loosen the highest joint; let trapped air hiss out, then retighten. Done—no sputtering [Elektroda, gruniu, post #16594828]
Generated by the language model.
ADVERTISEMENT