Water Not Flowing With All Three Valves Open

[BBC 489]

Hi,

The pool plumbing/pump was working fine until today when I drained about 18" of water from the pool (elevated CH). I refilled the pool and had a little trouble getting the pump to prime with the main drain open. This is strange for me because the pump is about 5 feet lower than the surface of the pool.

I got it working, but now I have the strangest problem. The water will flow to the pump with any of the three valves open, or any combination of two valves open. Water will not flow to the pump with a third valve open.

If I take the top of the pump skimmer basket off and open one valve, doesn't matter which one, water flows out of the top of the pump briskly. If I open another valve, doesn't matter which one, the flow is decreased, with the opening of a third valve water stops flowing.

If I have both pool skimmer valves open, there isn't an appreciable amount of water flowing through either pool skimmer. With one skimmer valve and the main drain open the skimmer has water flowing through it. Again it doesn't matter which valve is open.

In the attached picture from left to right the first valve is the deep end skimmer, the second or middle valve is the shallow end skimmer and the main valve is the third one.

Thanks a lot for reading through this,

Kevin

 

[Texas Splash]

This seems like a brain twister. I'll get it started by asking the following:
- How did you drain the water to lower the CH?
- How old is this pool and those 3-way valves?
- I think you have but want to make sure...... have you tried priming and running the pump for about 1 min or so by just one valve at a time to ensure the line is well purged?
- Have you checked the pump lid O-ring and drain plugs to ensure they have a good coating of pool lube for an airtight seal?
- Pool water height is good right?
- Skimmer weir doors operating freely?

I wonder if those 3-ways are old, if perhaps one of them is letting a little air in though its own O-ring seal? Might be worth a check at some point.

 

[BBC 489]

This seems like a brain twister. I'll get it started by asking the following:
- How did you drain the water to lower the CH?
- How old is this pool and those 3-way valves?
- I think you have but want to make sure...... have you tried priming and running the pump for about 1 min or so by just one valve at a time to ensure the line is well purged?
- Have you checked the pump lid O-ring and drain plugs to ensure they have a good coating of pool lube for an airtight seal?
- Pool water height is good right?
- Skimmer weir doors operating freely?

I wonder if those 3-ways are old, if perhaps one of them is letting a little air in though its own O-ring seal? Might be worth a check at some point.

Good Morning and thank you for replying.
1. Draining the water. I closed the skimmer valves, left the main drain valve open, closed the return line, removed the drain cap from the filter and turned the pump on low.
2. The pool will be 3 in September. The three way valves are right at a year old. They were replaced after the hard freeze last year, along with the pump. I converted to salt water at that time also.
3. Yes sir, I have run the pump on a single line for about five minutes each. I went out this morning and ran it on two valves open and had the third valve cracked for about 10 minutes with no improvement. It does sound and look like there is air passing through the third opened valve. It doesn't matter which valve is the third one, this morning it was the deep end skimmer valve.
4. O-ring and drain plugs. With the pump running the pump lid cannot be easily removed. I will go pull the plugs, remove the pump lid and coat the o-rings now again.
5. Pool water height is good.
6. The shallow end weir door was hanging up a little bit causing a cycling low water level. I have fixed that.