pipes banging loud when pump shuts off or turns on

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oldcoons

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Sep 19, 2018
11
Missoula Montana
Hi, I have a weird issue with our 16x32 vinyl inground pool system. I have a 1.5hp hayward super pump, sand filter and 5 roof mounted solar collectors for heat. Towards the end of last season we had an issue where I came home and my pool shut down (thankfully) and i found that a pipe from the pump was disconnedted. I put it back together, and from then on when the valve for the solar panels is all the way on, my pipes would shake and do a loud banging several times. Our installers came out and said we should recharge the sand filter because it was pretty full of junk. We just decided to winterize and have everything done in the spring when they come to open the pool. This spring we had the filter recharged and opened as planned however we are still unable to turn the valve all the way on for the solar panels or it thumps hard! also it really doesn't seem to be heating the pool as it did the year before. When the pump shuts down at night, it bangs so loud you can hear it in the house, same thing when the pump fires up in the morning. Our installers thought we may not have enough hp to pump that much so he bypassed one of the collectors to only use 4 of them, still same thing. Our installer is the only people in our Montana city and they just bought the business from the previous owner when he retired so they aren't well versed in all things pools yet. The filter gets backwashed when needed, we tried calling the manufacturer but they have never had a call on that issue. Has anybody had this sort of issue or have any info that might help? I would really appreciate any insight. Thank you

Gregg
 
I would suspect the check valve. I would check that to make sure that it's ok.

I suspect that the flapper has broken loose and is blocking the flow of water.

You're going to have to cut some pvc to get a look in the valve. I would plan to replace the valve and install some unions so that you can get to the valve in the future.

What's the dark line on the check valve? Is that a crack?

Maybe open the 3-way valve to check that as well.
 
We did open the valve with the handle and didn't see any blockage or anything. That has a piece of black tape in the middle between on and off. when i turn it all the way to on the flow stops to the chlrorinator and nothing comes out the return jets in the pool. If the check valve is the one in the back, I don't think it's a crack just a seam of some sort.
 
I really appreciate your insight! We close the pool on Tuesday for the winter, but I will order a new one for the spring. Geez, I hope it is that simple. It's been an enormous pain in the backside this year. Would that also be why we didn't really see much increase in the pool temps? We had a really warm summer but I suspect the solar blanket was the only thing heating the pool because the water coming out of the jets wasn't noticeably warmer as it was the previous year?
 
oldcoons said:
We did open the valve with the handle and didn't see any blockage or anything. That has a piece of black tape in the middle between on and off. when i turn it all the way to on the flow stops to the chlrorinator and nothing comes out the return jets in the pool. If the check valve is the one in the back, I don't think it's a crack just a seam of some sort.
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oldcoons said:
Another odd thing is when I turn the panel valve all the way to on it will make the bang and the returns will have no water coming into the pool.
Click to expand...

Sounds like that valve with the tape on it isn't working properly. That looks like the solar bypass valve - it directs water either to the solar panels and then back into the pool or directly back into the pool. When the pump is on I think you should have water returning to the pool regardless of that valve's position.
 

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sktn77a said:
Sounds like that valve with the tape on it isn't working properly. That looks like the solar bypass valve - it directs water either to the solar panels and then back into the pool or directly back into the pool. When the pump is on I think you should have water returning to the pool regardless of that valve's position.
Click to expand...
I actually made a short video of me turning that bypass valve to the on position and you can hear it thump the pipes and flow stops. I just can't get it to upload on this forum. My pool guy took it apart and thought it looked ok. It's very simple design inside, either on or off....or partially on, hence the black tape he put on there for me to not go past.
 
The flapper on the check valve swings on a hinge. If the hinge breaks, the flapper gets loose and slams into the exit of the check valve, which blocks the water flow.

That's what I would check.
 
Are you turning your solar on or off without first shutting off the pump?

If so are you turning very slowly or fast?

It's usually best to have the pump off when manually turning solar on or off.
automation valves turn very slowly so you don't get "water hammer" in your system.

That's the bang you are hearing.

But it does sound like that check valve may be the source of problems as others said.
 
borjis said:
Are you turning your solar on or off without first shutting off the pump?

If so are you turning very slowly or fast?

It's usually best to have the pump off when manually turning solar on or off.
automation valves turn very slowly so you don't get "water hammer" in your system.

That's the bang you are hearing.

But it does sound like that check valve may be the source of problems as others said.
Click to expand...

Yes we do turn it pretty slow. I don't usually even touch the handle much at all. When everything ran good, I would just leave it in the "on" position and the pump would just turn on and off with the timer. It is set up that way now, but only on halfway. when the pump turns on or off with the timer we will hear the thumps several times.
 
JamesW said:
Maybe listen right at the check valve to see if it sounds like it's coming from there.
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this makes sense to me, but I doubt we can tell where it exactly comes from. The thumps shakes the entire system and everything sort of jiggles. I sometimes wonder if our guy even set it up correctly to begin with. seems an odd place to put it if you are trying to resist back flow, maybe I have another one on the roof? i was reading that it should be somewhere to keep the water from coming back from the panels into the filter? I haven't looked. Does it look like it should be there? It looks to be before the chlorine feeder, then out to the return jets
 
You should have a check valve right as the water exits the filter and before it gets to the three way valve.

You can have a check valve at the return like you have, but it's not necessary.
 

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