Air Constantly Blowing Into Pool Through Return Jets

[up2you2]

Following the installation of a new Astral pump, when the filter is on, loads of bubbles are constantly being emitted through the inlet eyeball return jet.
A non returning valve had been fitted prior to the pump intake.
I use chlorine tablets.
The installer has already tried to resolve this problem without success.
Any suggestions please?

[Mrjlh]

Check for small traces of dirt on the pool floor just below the jets. If you see a dirt trail then you have a water/air leak in the pipes to the pool.  What happens is the leak is at point near a reduction joint where the water pressure going to the pool is greater than the the leak pressure. Acts in reverse. Dirt is actually sucked into the system.  When the pump is off then you may have a hardly noticeable water leak.  You can also have a small air leak at a joint.  Hard to tell when pipes are under ground but look for water leak signs for pipes above ground.  Cavitation is also has the appearance of air bubbles.  The water pressure at the jet is so great that it actually causes "air" in the water to be released as bubbles.  Try lowering the water pressure and see what happens.  Usually by closing a valve.  My best guess.  Anyone else?

[sappersrest]

Check to see if the basket is sitting correctly in strainer box, it should not be flush with the top, if it is not seated correctly the lid will not seal, check the o rings are seated correctly on the pump unions.

[grollies]

Assuming you didn't have this problem before, what is different this time to your previous set-up?

[up2you2]

There may have been a slight problem before, but it went away after a period the pump was on.

Now it is constant.

The installation of the non returning valve is new.

[sappersrest]

Why was the non return valve fitted, is it close to the pump?

If it is the brass type same as used on domestic water systems it will not be suitable for pool use due to the restriction the valve causes. Defiantly not for pool use will cause massive cavitation of the pump .

[sappersrest]

[sappersrest]

The above valve not for use on pump suction.

[grollies]

1 hour ago, up2you2 said:

There may have been a slight problem before, but it went away after a period the pump was on.

Now it is constant.

The installation of the non returning valve is new.

Move the non-return valve to the discharge side of the pump.

 

Reason is the NRV is restricting flow to your pump, causing cavitation (formation of air bubbles at the pump impeller due to low pressure causing the water to 'boil' at ambient temperature).

 

Have a long piece of pipe on the pump suction to even out the flow.

 

You can use a flap valve or, as @sappersrest says a spring-loaded valve. If a flap valve, place it in the vertical position.

 

 

[up2you2]

This is what I am currently using:

 

 

[RichCor]

Were ALL the issues involved in your prior swimming pool thread resolved?

 

Swimming pool leak.
Started by up2you2, November 10, 2016

 

Somebody squirted coloured water into where the walls meet the floor, and also along the bottom step of the pool.
Water was pouring out at quite a rate, in many places.
Once emptied they removed two tiles up, and two tiles from the walls.
Hacked out all the cement, half of it wet, they filled it with an extra strong bonding cement, that seemingly might not crack.

 

[up2you2]

1 hour ago, RichCor said:

Were ALL the issues involved in your prior swimming pool thread resolved?

 

Swimming pool leak.
Started by up2you2, November 10, 2016

 

 

Yes.

No noticeable drop of water outside of evaporation.

[sappersrest]

can you show where the non return valve is fitted, is the new pump bigger than the old, is there a vortex in the skimmer

 

[up2you2]

5 hours ago, sappersrest said:

can you show where the non return valve is fitted, is the new pump bigger than the old, is there a vortex in the skimmer

 

The non return valve is the grey valve, below the figure 4.

The replacement pump is the same as the old 1HP.

The pool is full to over flowing at the moment - no vortex in the skimmer.

[sappersrest]

It is very easy for someone to sit behind a keyboard and be critical of other peoples work without knowing the circumstances but here goes.

Basically the installation is a pump killer.

 

 In a space of 18 inches you have  4 x 90 deg bends  and a valve on 1 1/2 inch pipe, the last 90 being nearly connected directly to the pump.

Ideally you should have a distance of about 10 inches of clear pipe  i.e. no fittings connected to the pump.

 

The two 1 1/2 inch pipes should be common together with a 2 inch connection to the pump.

 

The setup you have will cause cavitation in the pump.

 

Also check as posted by MRJLH.

 

A tip to those building at the present bring suction pipe into the plant room using the same centerline height as your pump , or even slightly higher as yo can alway build a small plinth.

A good quality non return valve would not go a miss on the header to ease start up.

An essential bit of kit would be a pressure gauge on the pump discharge, 

 

[up2you2]

Thank you all these replies, I am grateful for them.

Obviously I have a configuration set up problem here, but from what you saying it is in fact soluble.

 

I need to employ Thai workers to do this, and here lies the second problem.

I need to convey to them exactly what needs to be done, and I feel this might best be explained by some kind of diagram chart.

 

I can easily add further photographs if this helps.

[grollies]

On 26/05/2017 at 9:43 PM, Mrjlh said:

Check for small traces of dirt on the pool floor just below the jets. If you see a dirt trail then you have a water/air leak in the pipes to the pool.  What happens is the leak is at point near a reduction joint where the water pressure going to the pool is greater than the the leak pressure. Acts in reverse. Dirt is actually sucked into the system.

 

Sorry but no, this does not happen. Water flows from high pressure to low pressure (i.e will leak out from a pressurized pipe), unless he has a venturi somewhere in his system.

 

On 26/05/2017 at 9:43 PM, Mrjlh said:

When the pump is off then you may have a hardly noticeable water leak.  You can also have a small air leak at a joint.  Hard to tell when pipes are under ground but look for water leak signs for pipes above ground.  Cavitation is also has the appearance of air bubbles.  The water pressure at the jet is so great that it actually causes "air" in the water to be released as bubbles.  Try lowering the water pressure and see what happens.  Usually by closing a valve.  My best guess.  Anyone else?

With respect, your explanation of cavitation is wrong and misleading.

 

Air bubbles do not form at the return jets due to high pressure, rather are the result of a restricted pump suction (i.e. non return valve) at the pump impellor, or turbulent flow (i.e. bends too close to the suction) causing low pressure at the impeller, to the point the vapour pressure of water is reached. There is a good explanation of cavitation here:

http://www.modernpumpingtoday.com/detecting-pump-cavitation/

 

[grollies]

2 hours ago, up2you2 said:

Thank you all these replies, I am grateful for them.

Obviously I have a configuration set up problem here, but from what you saying it is in fact soluble.

 

I need to employ Thai workers to do this, and here lies the second problem.

I need to convey to them exactly what needs to be done, and I feel this might best be explained by some kind of diagram chart.

 

I can easily add further photographs if this helps.

If you can put together a sketch of your existing set up and add a couple more photos, see how much room you've got?

 

Looks like the NRV is on the pump discharge but can you pull out on your photo to make things a bit clearer?

 

Is your pump above or below the pool water level?

 

Pump bolted down?

 

BTW, is the pump earthed?

[up2you2]

The pump is not earthed nor bolted down, but above the pool water level.

Additional images:

 

 

[RichCor]

@up2you2,

Can you provide an wide image (maybe slightly back from the doorway) to give an idea of how much room is available in your pump house.  

 

And when did the aeration issue start, any possible changes made/occurring around the same time?    

[grollies]

1 hour ago, up2you2 said:

The pump is not earthed nor bolted down, but above the pool water level.

Additional images:

 

 

You have a salt chlorinator cell and a chlorine dosing unit?

 

Your non-return valve is on the discharge side, after the cell and dosing unit. Are you sure the grey valve #4 is a non-return valve? Looks like it has a red handle? NRVs don't have valve handles.

 

Pipe size 1-14" or 1-1/2"?

[grollies]

6 hours ago, sappersrest said:

It is very easy for someone to sit behind a keyboard and be critical of other peoples work without knowing the circumstances but here goes.

Basically the installation is a pump killer.

 

 In a space of 18 inches you have  4 x 90 deg bends  and a valve on 1 1/2 inch pipe, the last 90 being nearly connected directly to the pump.

Ideally you should have a distance of about 10 inches of clear pipe  i.e. no fittings connected to the pump.

 

The two 1 1/2 inch pipes should be common together with a 2 inch connection to the pump.

 

The setup you have will cause cavitation in the pump.

Agree.

6 hours ago, sappersrest said:

 

Also check as posted by MRJLH.

 

A tip to those building at the present bring suction pipe into the plant room using the same centerline height as your pump , or even slightly higher as yo can alway build a small plinth.

By doing this you'd introduce an isolated high point before the suction, trapping air. For a pump above the waterline suction pipe must rise to the pump.

6 hours ago, sappersrest said:

A good quality non return valve would not go a miss on the header to ease start up.

An essential bit of kit would be a pressure gauge on the pump discharge, 

 

Also agree.

[up2you2]

1 hour ago, RichCor said:

@up2you2,

Can you provide an wide image (maybe slightly back from the doorway) to give an idea of how much room is available in your pump house.  

 

And when did the aeration issue start, any possible changes made/occurring around the same time?    

This aeration was already with the previous pump on occasions, but not nearly as bad and continuous as now.

Since the NRV has been installed this has exasperated the problem.

[up2you2]

1 hour ago, grollies said:

You have a salt chlorinator cell and a chlorine dosing unit?

 

Your non-return valve is on the discharge side, after the cell and dosing unit. Are you sure the grey valve #4 is a non-return valve? Looks like it has a red handle? NRVs don't have valve handles.

 

Pipe size 1-14" or 1-1/2"?

You have a salt chlorinator cell and a chlorine dosing unit?

Yes.

The salt chlorinator is shut off, and I am only using the chlorine dosing unit.

The grey valve #4, to be honest I do not know if it is the non-return valve.

Pipe size I think 1-1/2".

[RichCor]

4 hours ago, grollies said:

 

Do you get the same amount of air with BOTH inlet valves open?

The piping seems undersized to me.

[grollies]

16 hours ago, up2you2 said:

You have a salt chlorinator cell and a chlorine dosing unit?

Yes.

The salt chlorinator is shut off, and I am only using the chlorine dosing unit.

The grey valve #4, to be honest I do not know if it is the non-return valve.

Pipe size I think 1-1/2".

OK, do you see air bubbles in the clear lid of your pool pump?

[up2you2]

7 hours ago, grollies said:

OK, do you see air bubbles in the clear lid of your pool pump?

Yes.

[RichCor]

If you see actual bubbles (and not just vortex gaps) then your pump is actually ingesting air.

 

How to Identify and Correct Air Leaks
WRITTEN BY:  Inyo Pools

[up2you2]

- Resolved

Further developments have finally enabled me to find a resolution to this problem, to the extent that it has now been resolved.

Even prior to the final cure, running the backwash certainly helped alleviate a lot of the bubbles, to the degree that now only jets of water were now coming out of the jet nozzle.

But yesterday morning although the pump was still working, it was barely drawing any water.
Underneath the joint joining the actual pump it was leaking, with water on my pump room floor.
Further more on calling my Thai pump engineer, he noticed that the screw at the bottom of the back of the pump was loose.
On tightening up this screw, resealing the pipe to pump joint, all my problems have been resolved.
No bubbles and no jets of shooting water.

Thanks to all who helped in trying to resolve this problem. 

 

[grollies]

23 minutes ago, up2you2 said:

- Resolved

Further developments have finally enabled me to find a resolution to this problem, to the extent that it has now been resolved.

Even prior to the final cure, running the backwash certainly helped alleviate a lot of the bubbles, to the degree that now only jets of water were now coming out of the jet nozzle.

But yesterday morning although the pump was still working, it was barely drawing any water.
Underneath the joint joining the actual pump it was leaking, with water on my pump room floor.
Further more on calling my Thai pump engineer, he noticed that the screw at the bottom of the back of the pump was loose.
On tightening up this screw, resealing the pipe to pump joint, all my problems have been resolved.
No bubbles and no jets of shooting water.

Thanks to all who helped in trying to resolve this problem. 

 

Nice one .

 

The problem dignosed by air bubbles in the pump's clear lid.

 

Solution posted by @RichCor, good link mate.