Solar pump runs dry ~45seconds each time - Check valve required?

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paulr33
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Re: Solar pump runs dry ~45seconds each time - Check valve required?

Postby paulr33 » Sat 06 Jan, 2018 02:38

did some checking today. at power on, water starts flowing slowly into the swirl pot at 45 seconds. at 2 minutes the pump has enough prime for full flow and works normally from here on wards. when i turn the pump off instantly i can see some water flow back over the swirl pot but its only a couple of seconds, i wouldnt say its a full roof of water if that makes sense? its only a small flowback amount. but there shouldnt be any if the check valve is working? maybe he didnt install one?

here is the pipework;

at pump off, from doing a tapping test, i can tell there is water in the sections marked as green pipework. the sections marked yellow do not have any water in them at pump off. so it looks like the water pools only in the lowest gravity fed sections of the pipework and not the entire pipework.

there is also a joiner rubber tube as shown that joins both pipes, is this a breather tube?
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Denniswiseman
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Re: Solar pump runs dry ~45seconds each time - Check valve required?

Postby Denniswiseman » Sat 06 Jan, 2018 03:57

It doesn't look like there is a NRV installed
The reason why the green section has water in it is because there is a loop and it will always have water in it
I suspect that the problem is that the pump has to try and push that water while there is air in the pump
Do you know why that pipework is looped down? If you repipe it so it doesn't loop it may work better
Teapot
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Re: Solar pump runs dry ~45seconds each time - Check valve required?

Postby Teapot » Sat 06 Jan, 2018 15:14

Looks like a knuckle bend party!
If there has ever been a case for a NRV in front of the pump that's it.

It depends how much work you want to do obviously but removing some of the knuckle bends would allow you to wind down the pump a bit and save some bucks. I wonder what your main pump is and if it has enough grunt to lift the water around the heating?
paulr33
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Re: Solar pump runs dry ~45seconds each time - Check valve required?

Postby paulr33 » Sat 06 Jan, 2018 20:06

the big U shape bend is probably there because the solar pipework is installed by one company, then the pool installer installs the pumps and other stuff and the pipework is at different heights so he probably made it a big u shape to connect it all instead of redoing it properly. he did say a check valve was installed but maybe he never did it (wouldnt surprise me).

i can get my local plumber to fit one, no problems, should it go somewhere specific? as close to the pump outlet (to the roof) as possible?

once the solar pump pulls vacuum (after 2 minutes) and its running the system flows no problems and heats the pool easily, goes from around 22deg C to about 28deg C in a day in summer.
paulr33
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Re: Solar pump runs dry ~45seconds each time - Check valve required?

Postby paulr33 » Sat 06 Jan, 2018 20:31

i should have checked this earlier, from the vendor manuals of the solar pump;

For pump installations 500mm above water level, it generally requires a foot valve at the pool or check valve in the suction line. Suction lines must be installed below water level until just in front of pump location and vertical riser used to reach pump inlet. AstralPool pumps are rated to a maximum head of 25 meters however refer to your pump’s data plate for actual achievable pressure.

I reckon mine would be 500mm above easy
Denniswiseman
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Re: Solar pump runs dry ~45seconds each time - Check valve required?

Postby Denniswiseman » Sun 07 Jan, 2018 04:38

It seems you have found your answer
You don't have a NRV
Place the NRV in the suction side to the pump to keep the pump primed (you would have to find a convenient place to put it)
paulr33
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Re: Solar pump runs dry ~45seconds each time - Check valve required?

Postby paulr33 » Sun 07 Jan, 2018 06:31

ok thanks a lot, i will place it just before the solar pump inlet
Denniswiseman
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Re: Solar pump runs dry ~45seconds each time - Check valve required?

Postby Denniswiseman » Sun 07 Jan, 2018 09:15

When you turn your pump on for the first time after fitting the NRV you will still experience a delay until your pump primes after that it should be plain sailing
Report back to let us know how you get on
paulr33
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Re: Solar pump runs dry ~45seconds each time - Check valve required?

Postby paulr33 » Sat 20 Jan, 2018 19:55

this was the so called one way valve.....

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so ive removed that and fitted this... a bit better =)

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need to wait 24 hours then see how it cranks...
Denniswiseman
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Re: Solar pump runs dry ~45seconds each time - Check valve required?

Postby Denniswiseman » Sun 21 Jan, 2018 04:08

I had one like that on an Onga pump but the flap just broke off (I didn't need it)
That one should definately keep the pump primed
It may be an idea to fill the pump via the the basket to prime the pump before you start it, just to help it initially get over a long prime
Are you in a freeze area, if so it may be an idea to fit a drainoff in those loops
Teapot
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Re: Solar pump runs dry ~45seconds each time - Check valve required?

Postby Teapot » Sun 21 Jan, 2018 12:25

Oh come on Paul, crank it into life! it's been like waiting for the birth of your first child, we want to know :-)
paulr33
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Re: Solar pump runs dry ~45seconds each time - Check valve required?

Postby paulr33 » Mon 22 Jan, 2018 02:52

ok all sorted, check valve working and no leaks or issues. dry prime time is about 40 seconds if I pour water into the well and fill it which is a great improvement over 2mins 20secs. the best part is when i turn the pump off and back on again the prime time is about 5 seconds at most and its running full flow. very happy and a massive improvement. thanks all. just shows the benefits of a properly designed pipework system taking into consideration the water level etc.

how good was the supposed "check valve" that was installed, what a joke....
paulr33
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Re: Solar pump runs dry ~45seconds each time - Check valve required?

Postby paulr33 » Mon 22 Jan, 2018 02:54

no chance of freeze area in melbourne, our winter lowest temps are around 10deg C
Denniswiseman
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Re: Solar pump runs dry ~45seconds each time - Check valve required?

Postby Denniswiseman » Mon 22 Jan, 2018 03:31

Congratulations on a successful resolution to your problem
That check valve is an integral part of the pump designed to keep a filter full and they break off any way
Teapot
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My Pool: 12 x 24 (45m3) liner pool, Triton TR60 filter with AFM glass media (Activate) and variable speed pump running 0.08HP
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Re: Solar pump runs dry ~45seconds each time - Check valve required?

Postby Teapot » Mon 22 Jan, 2018 17:17

Great news and thank you for coming back to share it.

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