Plumbing Help - Location for Check Valves

[Patflemming]

Hi everyone, first post here.

I would like to some opinions on where the ideal locations would be to install check valves on my pool plumbing. I am trying to solve the following 2 issues:

1- It's challenging to blow out my solar panel heater lines before winter. I'm thinking of adding a union somewhere to make it easier to blow out the lines. When doing research, I noticed most installs have check valves on the solar panel plumbing. Is it best to have one on the supply or return pipe?

2- The pump return line to my pool is really long. The pump loses its prime easily after it's been turned off. Would a check valve installed right after the pump help solve this issue?

 

[mas985]

Welcome to the forum!

Hi everyone, first post here.

I would like to some opinions on where the ideal locations would be to install check valves on my pool plumbing. I am trying to solve the following 2 issues:

1- It's challenging to blow out my solar panel heater lines before winter. I'm thinking of adding a union somewhere to make it easier to blow out the lines. When doing research, I noticed most installs have check valves on the solar panel plumbing. Is it best to have one on the supply or return pipe?

How would a check valve improve winterizing the lines? The reason reason you see check valves on the return side of the solar panels is to prevent the panels from filling when the solar valve is in the off position. You will also see check valves right after the filter so that when the solar panels drain, assuming there is a VRV installed, the panels will not drain backwards through the filter. These are the only two locations and reasons for check valves in solar.

2- The pump return line to my pool is really long. The pump loses its prime easily after it's been turned off. Would a check valve installed right after the pump help solve this issue?

No that will not help. The reason that the pump is losing prime is because air is leaking into the plumbing somewhere is shouldn't. This is usually the pump lid gasket and/or drain plug gaskets. A little pool lube on each should help with air leaks.

 

[Patflemming]

How would a check valve improve winterizing the lines? The reason reason you see check valves on the return side of the solar panels is to prevent the panels from filling when the solar valve is in the off position. You will also see check valves right after the filter so that when the solar panels drain, assuming there is a VRV installed, the panels will not drain backwards through the filter. These are the only two locations and reasons for check valves in solar.

Sorry, I should have specified that I would install unions to allow for better winterization.

No that will not help. The reason that the pump is losing prime is because air is leaking into the plumbing somewhere is shouldn't. This is usually the pump lid gasket and/or drain plug gaskets. A little pool lube on each should help with air leaks.

I don't think I explained it correctly. The pump doesn't lose its prime really. It's when I open the filter cover, then the basket empties and the water drains out the pool return line, which is very long. When I close everything back up and turn the pump back on, it runs dry for a good 30-45 seconds before it can pull water from the pool. I even try to fill the basket up with a hose but it empties itself just as quickly. I figured a check valve installed right after the pump would allow my to keep my filter basket filled with water and avoiding my pump from running dry.

 

[mas985]

Sorry, I should have specified that I would install unions to allow for better winterization.

I don't think I explained it correctly. The pump doesn't lose its prime really. It's when I open the filter cover, then the water drains out the pool return line, which is very long. When I close everything back up and turn the pump back on, it runs dry for a good 30-45 seconds before it can pull water from the pool. I figured a check valve installed right after the pump would allow my to keep my filter basket filled with water and avoiding my pump from running dry.

A check valve would still allow water to drain from the pump out the returns. A check valve only stops reverse flow.

To prevent flow out of either end of the pump, you need 2-way valves on BOTH the suction and return lines to fully isolate the pump from the pool.

How high is the pump above water level?

If the pump is fairly high relative to water level, it can take more time to prime the pump but 30-45 seconds is not an issue and the pump is not really "running dry" as it should have water in the pump basket filled to the inlet port level. This makes the pump easier to prime.

 

[Patflemming]

A check valve would still allow water to drain from the pump out the returns. A check valve only stops reverse flow.

The water gravity drains back to the pool through the incoming supply line to the pump. Wouldn't a check valve before the pump keep the basket full at all times? The filter inlet in a good 2-3 feet higher than the pump. The water wouldn't be able to drain in that direction.

To prevent flow out of either end of the pump, you need 2-way valves on BOTH the suction and return lines to fully isolate the pump from the pool.

I don't know if this would work. Once the valves are opened before starting up the pump, the water would gravity drain out again, just like the original problem.

 

[mas985]

The water gravity drains back to the pool through the incoming supply line to the pump. Wouldn't a check valve before the pump keep the basket full at all times?

No because the water will drain out of the return side just as easily.

The filter inlet in a good 2-3 feet higher than the pump. The water wouldn't be able to drain in that direction.

Sure it will. It is called a siphon. Water will naturally flow from higher elevation to a lower elevation. It doesn't matter if there is a higher elevation in between. Water will still runout of a return.


Note that the hose is higher than the source water level. It can actually be close to 30' higher and a siphon will still exist.

I don't know if this would work. Once the valves are opened before starting up the pump, the water would gravity drain out again, just like the original problem.

You would first fill up the pump basket completely with water. Then close the pump basket lid and seal it tight. Then open the valves. There is no way for air to enter the system at that point so no water would drain out.

 

[mas985]

Another example with larger pipe: