Airlock in secondary (cleaner) pump

[JamesW]

I don't think that it's a pump issue. The pump is not self priming. It requires a flooded suction. I suspect that the way it's plumbed allows air to build up in the pump.

If the booster pump suction Ts into the underground return line, there might be insufficient pressure to move water through the pump.

The T might even create a venturi effect, which can lower the pressure even more.

You need to put the booster pump intake on the return line in a way that water continuously flows through the booster even when the booster is off.

 

[Flyguppy]

I don't think that it's a pump issue. The pump is not self priming. It requires a flooded suction. I suspect that the way it's plumbed allows air to build up in the pump.

If the booster pump suction Ts into the underground return line, there might be insufficient pressure to move water through the pump.

The T might even create a venturi effect, which can lower the pressure even more.

You need to put the booster pump intake on the return line in a way that water continuously flows through the booster even when the booster is off.

Any suggestions on how to proceed?

Sounds like more than a DIY. And digging up plumbing, rerouting, etc sounds expensive. Want to make sure that will fix the issue.

 

[JamesW]

Can you post pictures of the the whole system and where the booster suction Ts into the main return line?

If you ever use Spa Only mode, you have to connect the booster suction to the pool return after the three way valve and you have to keep the booster off when in Spa Only mode.

 

[Flyguppy]

Can you post pictures of the the whole system and where the booster suction Ts into the main return line?

If you ever use Spa Only mode, you have to connect the booster suction to the pool return after the three way valve and you have to keep the booster off when in Spa Only mode.

That will involve some digging, as the line is flex from the pump, connects to a hard PVC line, them does a 90 straight into the ground.

Not home until Tuesday night, so any pics would be Wednesday at the earliest.

 

[JamesW]

You might be able to cap off the existing line and just T into the return at a different spot.

 

[mas985]

I don't think that it's a pump issue. The pump is not self priming. It requires a flooded suction. I suspect that the way it's plumbed allows air to build up in the pump.

We have already confirmed there is PRESSURE on suction side of the booster pump. When that suction line is removed from the booster, water comes out so the booster pump has a flooded suction.

Unless there is a blockage within the pump or after the pump.

 

[JamesW]

Maybe a problem with the booster pump or the line going from the booster to the cleaner.

However, it seems that once it catches prime, it runs ok.

Definitely odd.

 

[mas985]

If it were me, I would take apart the pump and two lines to see if there are any loose pieces that could potentially block the flow.

Inspect the cleaner and cleaner lines too.

The first part of this shows disassembly.

 

[JamesW]

There should be water coming out of the wall fitting with the main pump on and the booster off.

A clog at the pump or beyond could explain it but it seems to work ok once it catches prime.

If there was a complete clog, I would expect that the booster wouldn't work at all.

If there was a check valve on the booster pressure line, that might cause the issue.

A check valve would prevent low pressure flow but would allow higher pressure flow.

Once you get the pump disconnected, you can put a garden hose at the wall return to see if water will flow backwards to the pump and from the pump to the wall.

 

[mas985]

I have seen these boosters get clogged with small debris and if it moves backwards, it will unclog. So it is not a 100% clog but a periodic clog due to the shape debris and the chance it gets lodged in the correct position.

 

[JamesW]

Definitely worth checking for a clog.

 

[Flyguppy]

Thank you gents.

Will get to work Wednesday and report back.

Regards

Brad

 

[Flyguppy]

If it were me, I would take apart the pump and two lines to see if there are any loose pieces that could potentially block the flow.

Inspect the cleaner and cleaner lines too.

The first part of this shows disassembly.

Mark,

Watched this in prep for Wednesday.

Basically go to the point of taking the impeller off and look for loose pieces or the 'melting' they mention?

Don't need to go any further than that?

Thanks

 

[mas985]

You shouldn't need to take of the impeller but make sure it is on the shaft tight. Just look for anything loose in that area.

But more than likely, I would expect any clog to occur in the hoses. Before taking apart the pump, just try and back flush those lines and see if anything comes out. Also, inspect the cleaner line for anything.

 

[Flyguppy]

Thanks to thunderstorms around Philly on Tuesday, didn't get home until late Wednesday.

Pump apart. No loose pieces that I could find. (The cleaner was working when I turned things on this morning).

Here are pics of the impeller. Not sure what the 'melting' looks like that is mentioned in the video.

So....dunno.

- - - Updated - - -

How do I back flush the supply line?

I can back flush the cleaner line by a hose on the wall fitting. I suppose I can put a hose on the supply line, but wouldn't be able to see if anything comes out?

 

[JamesW]

You need a new seal and impeller.

Probably damaged by running dry.

I think you're going to have to replumb.

 

[mas985]

You need a new seal and impeller.

Probably damaged by running dry.

I think you're going to have to replumb.

I can see that the rubber around the seal is damaged but why replace the impeller if it is not damaged?

Also why does the OP need to re-plumb?

 

[Flyguppy]

OK....a little more info......

1. Backwashed from wall fitting to PVC by pump. No debris. Ran some water into the supply line that feeds pump.

2. Put everything back together.

3. Started up VS. Went to bare wall fitting, nothing coming out. (should be a trickle, right?)

4. Started up booster, heard it prime, see water coming out of wall fitting.

5. Shut off booster, BUT KEPT VS running. Tried increasing VS speed from 2700 to 2850.

6. Here's where it gets interesting......water coming from wall fitting at a slower rate obviously (GOOD I think). Put hand over wall fitting and water seems to slow in intensity....remove hand and a few to ten air bubbles come out of wall fitting. Put hand down and water is still coming out of wall. Hand over fitting, water seems to slow...eventually almost STOP flowing....remove hand, air bubbles.

I tried to do it until water stopped flowing completely, but I think that would take a couple days. Ha! But with the cleaner attached, that air builds up to what I term, an airlock.

 

[mas985]

Are you seeing air in the main pump basket? That air must be coming from somewhere and while the pump is running it can only really come from the suction side of the main pump. But that air should just push through the booster pump and water should then enter the pump because it is under pressure. Unless it is a very large air leak. Is there a air purge valve on the filter and if you open it, does air come out?

When you had the booster apart, did you look into the vanes of the impeller for any blockage?

 

[Flyguppy]

Are you seeing air in the main pump basket? That air must be coming from somewhere and while the pump is running it can only really come from the suction side of the main pump. But that air should just push through the booster pump and water should then enter the pump because it is under pressure. Unless it is a very large air leak. Is there a air purge valve on the filter and if you open it, does air come out?

When you had the booster apart, did you look into the vanes of the impeller for any blockage?

Minimal air in the VS pump basket, like a bubble or two once in awhile, but not much. Water out of the relief valve on top of filter (when pumps on obviously), maybe a quick escape of air, but nothing noticeable.

Didn't know about looking inside the vanes.....like hold it up to the light? Can you see thru them? I didn't make a point to look at the vane openings. But the ones I saw didn't have blockages.