Rebuilt equipment pad, still losing prime, what's next?

[suburbiaboy]

Hi, last summer I started a thread about renovating my pool. I've had constant problems with being unable to keep the pump primed when running only from the skimmer and air in the pump when vacuuming. After discussion with @Arizonarob @Soupy and @mas985 the first priority was determined to be to completely replace the awful equipment pad so that can be ruled out as a problem.

I've now completed that work and the symptoms remain the same. In fact things are now worse, as the suction port has now been plumbed back to a return and now I can no longer prime the pump at all (the same as before when the suction port was closed). I've attached a picture of the new pad, sorry about the quality.

Symptoms:
1. Pump does not fully prime, it gets close then drops and slowly works it's way back before dropping off again
2. Huge bubbles come from the returns (either/both)
3. After turning off the pump it immediately drains down to the inlet and there are lots of glugs from the filter valve as I assume air works it's way back in

Video of the pump after rebuild

What I've done:
1. Checked for air leaks with smoke – nothing obvious
2. Re-lubed all the o-rings in the new unions, the pump lid, the pump body and the filter valve

So now I'm at a loss, what do I do now?

 

[avspin]

Have you tried a check valve to prevent water drain out of the line?

 

[mas985]

Do you have solar? If not, water should never drain out of the pump when it is shut off. If it does, there is an air leak. You just need to find out where it is.

 

[Andrew_D]

Time to see if the lines will hold air pressure? Same as how a new pool install is done? This would have been easier to do after the old pad was torn apart, but before the new pad was assembled. Plug the lines in the pool. On each line at the pad, attach a tee with gauge, ball valve, air regulator. Use air compressor to bring the pressure up slowly. Not sure how much to run, I'd start slow. 5-10 psi. Charge the line. Make sure there are no air bubbles at the plug in the pool. Close the ball valve and watch the gauge. If the pressure drops, you know you have a leak. Test all 3 lines. If all is good, raise the pressure and retest. How high can you go on the pressure? Hopefully someone will chime in with how high builders go on new installs. Lots of pool pumps are in the 20-50 psi range, so I'd test up to that level. If there's air getting to the suction side, you should only have to check the skimmer line, but I'd like to know that all 3 are OK....

Andrew

 

[suburbiaboy]

@mas985 would the air leak still be on the suction side? Just wondered if the pump draining out could signify a leak elsewhere.

@Andrew_D testing the suction line like that might be possible, the others might be tricky. Would need to find a way to connect the compressor to the poly pipe and buy a new skimmer plug as the dog just ate mine

 

[mas985]

If the pump loses air slowly when it is turned off AND it primes ok, then it is possible for the air leak to be on the return side of the pump. Normally this occurs in the multi-port valve and you should be able to hear it after the pump is off. The filter will gurgle and continue to do so until the pump is drained.

However, if the pump drains right away after being turned off, then it is more likely to be a suction side air leak. Also, if you are getting constant air bubbles in the pump basket, that too is an indication of a suction side air leak.


Did you ever take the pump apart and directly inspect the impeller for block?

 

[suburbiaboy]

@mas985 ok, thanks. So it seems most likely that it's on the suction side then – given that the pump doesn't prime well or stay primed and I saw no leaks anywhere on the discharge side.

Since this is now happening on the third set of pad plumbing I guess I need to look at the skimmer and the skimmer line. Is there any other simple way to test other than the method that Andrew mentioned? I can go that route but I don't have all the equipment.

 

[Andrew_D]

You have a valve on the suction side, so can use it to turn off the suction line. Since you are going to be pressurizing the suction line, I would turn the valve towards the pump so that the flap inside the valve gets pushed closed by the air pressure.

Then get a winterizing plug such as Amazon.com: Rubber Winterizing Expansion Plug 1.5" Fitting, Plug Size 10: Home Improvement. This is a 1 1/2" one, there are other sizes available depending what size the hole on the bottom of your skimmer is. You'll also need some lamp threaded rod Amazon.com: Lamp Rod,All Thread Lamp Pipe,Lamp Repair Assortment of Hardware,Yellow Zinc Coated, Includes 12"Lamp Pipe Nipples, 24 Washers, 24 Lock Nuts: Home Improvement. Drill the center of the rubber plug just big enough to get the lamp threaded rod through. Washer and double nut (locked together) on bottom. Washer and nut on top. Place it into the hole at the bottom of the skimmer and holding the rod, tighten the top nut. Lamp rod is 1/8" pipe.

Also need:
1/8" gauge Amazon.com: Pressure Gauge,Liquid Filled,1.5" Dia,0-60 psi/bar/kpa,1/8" NPT Male Brass Connection,Back Mount, Polycarbonate Lens Window, Stainless Steel case: Industrial & Scientific
1/8" tee Amazon.com: NIGO Industrial Co. Brass Pipe Fitting, Forged Brass Tee, 3-Way, NPT Female X NPT Female X NPT Male (1, 1/8" x 1/8" x 1/8"): Home Improvement
1/8" tank valve https://www.amazon.com/Performance-Tool-60505-Tank-Valve/dp/B006G4HSTU
1/8" ball valve uxcell Brass Air Ball Valve Shut-Off Switch G1/8 Female to Female Pipe Tubing Fitting Coupler 180 Degree Operation Handle 4Pcs: Amazon.com: Industrial & Scientific

Place the tee on the lamp rod. One port of tee gets the gauge. Other port gets the ball valve. Put the tank valve into the ball valve.

Now, you "should" add air to this using a regulator to do it slowly. Some air compressors have a regulator built on them that you can use. Or..... if you're careful.... just crack the ball valve a wee bit and add air VERY slowly.

Once you bring it up to your testing pressure, close the valve and wait. If there's a leak, the pressure will drop.
That's the easy part.
Now, ya gotta find the leak!

Andrew

 

[avspin]

I made a pressure testing jig with pvc. Used a 1 1/2 threaded fitting to go in the skimmer or returns. Then a union so you can screw it in and out. Then a place for a pressure gauge and finally a hose fitting to attach a hose to pressurize the line. Oh you will need a ball valve before the hose fitting to shut the water off and keep the pressure.
Doesn't have to be pretty. I used 3/4 pvc.

 

[mas985]

When running the pump, have you looked in the skimmer to make sure it isn't sucking air?

Did you inspect the pump impeller?

 

[Arizonarob]

I’m glad you replumed the pad, if memory serves, it was a mess.
I’ll chime in tomorrow when I have more time. In the mean time, mas985 is one of our plumbing experts.

 

[suburbiaboy]

Wow that’s great @Andrew_D that completely makes sense, thanks for the links. So I’d be pressure testing from the skimmer end which means I’d be testing not only the skimmer line but also the plumbing up to the valve which is useful to rule out issues there. My compressor has a regulator and I have some of those plugs already so actually this could be easier than I thought. Until I confirm a leak of course!

 

[suburbiaboy]

@mas985 yes I looked in the skimmer. As long as the basket is in it doesn’t suck air. I did look look at the impeller, it looked ok. I haven’t replaced any of the pump o-rings or seals but they looked ok when I lubricated them and there’s no leaks from the pump.

@Arizonarob yep your memory is correct, it was a spaghetti monster of flex pipe and weird routing, I’ve linked to it somewhere above. I’m quite pleased with the new setup It’s a tight space but it’s quite neat. I’d be more pleased if it worked though...

 

[suburbiaboy]

@avspin thanks for the pic, that does look like a useful testing jig.

 

[Arizonarob]

So it looks like the guys above have you on the right track. Now that your plumbing is squared away at the pad, it’s going to be a process of elimination to find the leak.
We’ll get this figured out and have you enjoying your pool in no time. Keep us posted on your findings.

 

[suburbiaboy]

Thanks @Arizonarob !

Related to the question @mas985 was asking yesterday, I noticed whilst paying around that if I fill the pump to the lid and seal it up, the water will pretty quickly drain out below the inlet but ALL the bubbles are quite clearly coming from the impeller side – is that significant or to be expected?

I assume this is a red herring since the pump can't keep prime, which points to a suction side issue?

 

[mas985]

With the pump above water level it is nearly impossible to fill the pump basket and put the lid on without the water draining out.

If the pump is not priming, either the impeller is clogged, suction pipe is clogged or there is a suction side air leak.

But earlier you mentioned that without the skimmer basket, the skimmer will suck in air. Are you absolutely sure that even with the skimmer basket installed that the skimmer is still not sucking air. It would explain everything. Can you take a video of the skimmer with the skimmer basket and the pump running?

 

[suburbiaboy]

I went to take a video but I needed to top the water up a little first which is possibly telling since the thick winter cover is still on and I topped it up yesterday.

So just for fun I placed a winter plug in the skimmer and filled the the skimmer line from the pump basket and it doesn't stay filled. The water gets to the top of the basket and slowly drops back down to the inlet level. That seems somewhat definitive that I have a leak?

 

[mas985]

I am confused about what you are doing. If you pour extra water in the skimmer basket, it should run out the front of the skimmer inlet into the pool. Is the water level below the bottom of the skimmer inlet? It should be half way up the skimmer inlet.

 

[suburbiaboy]

No I put water in the pump with the skimmer plugged.

I.e., I put a plug in the skimmer outlet (at the bottom of the skimmer) and then slowly filled the pump with a hose allowing the water to flow into the skimmer line. Once the line was filled the pump also filled to the top. But the water level in the pump basket immediately drops to below the inlet when the hose is turned off. A no-pressure pressure test.