Pump unable to pull from Main Drain

[laszlof]

I'm not sure what the problem here is, but my main filter pump (Jandy 1.85 VS Pump) is unable to pull from my main drains. Theres a 3" line that runs from both main drains, and T's off into 2 pumps. 1 pump (a 2.7HP Waterways VS Pump) is ONLY fed by the main drain, and has zero issue (even at low RPMs) pulling from it.

On the filter pump, there is a 3 way valve that allows me to switch from skimmer, to main drain, or any combination of both. Anytime I introduce any amount of MD to the mix, it loses prime and is unable to pull water through the pipe. I've tried just about every combination of valving to get it to go, and nothing allows the pump to prime.

Anyone have any thoughts on what the issue may be?

Heres an older pic of the plumbing setup. The pump to the left is the waterfall pump, which is only plumbed to the 3" main drain line. The pump to the right, is the filter pump, which has a jandy 3 way valve split between main drain (left) and skimmer (right)

 

[JamesW]

Try closing the valve to the Waterway fountain pump.

You should have a check valve at the discharge of both pumps so that the other pump cannot pull water backwards from the other pump.

 

[laszlof]

Try closing the valve to the Waterway fountain pump.

You should have a check valve at the discharge of both pumps so that the other pump cannot pull water backwards from the other pump.

Thanks. Already tried that. Still wont pull water through.

So place a check valve between the jandy valve and the pump inlet on both pumps?

 

[JamesW]

You should have a check valve at the discharge of both pumps

 

[laszlof]

both pump discharges are completely separate. The waterways pump just goes straight back to a 3" pipe to the waterfall. The jandy pump goes into the filter.

 

[JamesW]

1 pump (a 2.7HP Waterways VS Pump) is ONLY fed by the main drain, and has zero issue (even at low RPMs) pulling from it.

Anytime I introduce any amount of MD to the mix, it loses prime and is unable to pull water through the pipe.

If the Waterways pump works on the line, the filter pump should also work if the line to the Waterways pump is closed.

If the Waterways line is open, the filter pump will suck water backwards from the fountain and get air from the fountain.

 

[laszlof]

If the Waterways pump works on the line, the filter pump should also work if the line to the Waterways pump is closed.

If the Waterways line is open, the filter pump will suck water backwards from the fountain and get air from the fountain.

I've tried isolating the pumps as I mentioned above. I completely closed/turned off the waterfall pump and flipped the jandy pump to just pull from the MD. It would not pull water into the basket, even at high RPM.

 

[JamesW]

 

[JamesW]

Show how you are configuring the valves.

 

[laszlof]

Show how you are configuring the valves.

Heres the configuration under normal operation. With this, the filter pump pulls 100% from the skimmer, and the waterfall pulls from the MD.


And here is the confirmation when trying to pull from the MD on the filter pump


The waterfall pump is completely closed in this configuration, and I barely get a trickle of water coming from the main drain into the filter pump.

 

[JamesW]

Maybe the builder did something to the pipes underground before covering them?

Maybe dig it up to see what's what.

 

[laszlof]

Maybe the builder did something to the pipes underground before covering them?

Maybe dig it up to see what's what.

What would they have done to the pipes? I was present during the entire process and during the burying as well. I'm fully aware of where every pipe goes and how its connected.

One thought I had, and I might be completely off base. In the 2nd configuration, trying to pull from the main drains into the filter pump, there is likely a large air bubble on the vertical pipe going to the valve for the waterfall pump. Would this air pocket cause the pump to never prime? Would that air pocket eventually bleed itself out?

 

[JamesW]

What would they have done to the pipes?

I don't know, that's why I would dig it up and check.

In the 2nd configuration, trying to pull from the main drains into the filter pump, there is likely a large air bubble on the vertical pipe going to the valve for the waterfall pump. Would this air pocket cause the pump to never prime? Would that air pocket eventually bleed itself out?

The pump might take a few minutes to prime, but it should catch prime eventually.

 

[laszlof]

I don't know, that's why I would dig it up and check.

The pump might take a few minutes to prime, but it should catch prime eventually.

Yeah, I figured it out. The elbow going from the main drain into the 3 way valve and filter pump isn't fully glued. There's an air leak there. It's probably seeping it's way to a lesser extent into the waterfall as well.

Thanks for your help in diagnosing!

 

[laszlof]

Going to have them come out and fix this, and run a full pressure test. This is the 2nd time I've found something that was fully glued. the last one was under ground and caused a ton of sand to run into my pool when it separated on a return line.

 

[JamesW]

Many places require a pressure test before the inspection is passed.

It seems like they took some shortcuts.

 

[laszlof]

Many places require a pressure test before the inspection is passed.

It seems like they took some shortcuts.

Yup. has me concerned for sure. I dont think we require pressure tests for water lines, just gas. But they should have done one anyways. Seems like standard practice to make sure you got everything sealed up well before closing up holes.