Unable to prime pump - new setup

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necostanzo

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Aug 2, 2009
3
First off, much thanks to all the experts here. It has made a huge difference in setting up my new pool.

Problem: I am unable to prime the pump. It is located on a concrete pad about 40' away from the pool and about 10' above the pool. I open the pump and fill it up with water, close it up, then start the pump. It pulls the water for about 20" then stops. It appears to get an airlock. I just turn off the pump and try again. After many attempts, my brother and I were able to get it primed and it ran about 24 hours without issue. My brother tried to hookup the vacumm and clean the debris off the bottom, but he too lost suction after about 20". I told him to just turn it off and wait til I get back home.

Equipment:
18x36 inground rectangle
aquagenie (no main drain)
500# hayward sand
Hayward Max Flo2 2hp pump
2" lines - 2 of them both go to the aqaugenie - I'm using Sch40 flex pipe with no joints until we start to climb the hill and then we installed a spring loaded check valve and a 1 1/2" bypass valve to make it easy to drain in the winter.

I just don't understand how we are losing suction and what is going on. If anyone can lend a hand, I'd greatly appreciate it.

Much Thanks in advance, Nick
 
Welcome to TFP.

10' is a lot of lift. Are filling just the pump basket, or the pipe down to the check valve? Filling the pipe should let you prime.

When he hooked the vacuum up, did he fill the hose with water first? An empty hose will cause a loss of prime.
 
Like John said, your check valve should be holding the water in the pump basket allowing it to prime easily.

If your water is draining all the way back to the pool, your check valve is not working.
 
To explain further... yes we were filling the 2" pipe all the way up the hill...even after we did that it still wouldn't prime after about 5-7 attempts...we finally opened the check valve bypass and ran the water in the hose all the way to the pool...that still didn't work...it wasn't until we opened the heater bypass did it finally take the prime. Couple of questions;

#1. I figured out that if we plug the suction line at the bottom of the aquagenie, we can fill the entire line from the pump to the pool and prime it, but it takes 2 people to make it work (1 to start the pump and one to pull the cap off the suction line)...If the bypass is closed and I turn off the pump why is it losing it's prime?

#2. I don't understand how a closed system can lose it's prime when I turn it off for 1 minute without opening anything. Can someone explain why I would lose the prime if everything is working and I just turn off the pump for 1-2 minutes to hook up my vacuum?

#3. The hayward manual says that the pump is "self priming". It's says don't run it dry, but it says that it can run for 5 minutes to prime itself. What's going on here? Do they mean that if I fill the basket with water, I can run it for 5 minutes to see if it will prime before I turn it off? I've only been running it for 20-30 seconds after I realize that it lost its prime.

#4. From the pump to the filter to the heater, it then runs right back down the hill. Can air on the return side affect the pump? I assume that as soon as I turn off the pump, water runs down the hill to the return line.

#4. Can someone give me some failsafe techniques for this setup? I have just backfilled and can replace and or digup anything that I have done and replace it with the proper setup.

Much Thanks again, Nick
 
necostanzo said:
#1. I figured out that if we plug the suction line at the bottom of the aquagenie, we can fill the entire line from the pump to the pool and prime it, but it takes 2 people to make it work (1 to start the pump and one to pull the cap off the suction line)...If the bypass is closed and I turn off the pump why is it losing it's prime?

#2. I don't understand how a closed system can lose it's prime when I turn it off for 1 minute without opening anything. Can someone explain why I would lose the prime if everything is working and I just turn off the pump for 1-2 minutes to hook up my vacuum?
Click to expand...

Without a check valve, the weight of the water in the suction line creates a vacuum through the pump and filter when the pump is off. If air can find it's way in, the water will drain out. It sounds like your check valve isn't working. Some require pump pressure to seal, which means they will drain under the lower pressure of the water standing in the suction pipe.


necostanzo said:
#3. The hayward manual says that the pump is "self priming". It's says don't run it dry, but it says that it can run for 5 minutes to prime itself. What's going on here? Do they mean that if I fill the basket with water, I can run it for 5 minutes to see if it will prime before I turn it off? I've only been running it for 20-30 seconds after I realize that it lost its prime.
Click to expand...

My pump takes more than 20-30 seconds to prime with empty lines and an empty basket, and mine is sitting at pool deck height. I'd let it run at least a couple of minutes to see if it is making progress.
 
Can you post a pic of your setup? I think that would help a lot.

Here's just a few thoughts.

It sounds like to me that you're at the limit of total head that the pump can handle.
You said that you have a spring loaded check valve so that's adding head. You also have to bypass the heater to get it to prime. It also adds head. You're pump is 10' higher than the pool so there's more head. The filter adds head. The only thing not adding head is the downhill return to the pool.

If it's losing prime as soon as it's shut off, either you have an air leak in the system somewhere allowing air into the pump, or the check valve isn't holding.
 
Can someone explain why I would lose the prime if everything is working and I just turn off the pump for 1-2 minutes to hook up my vacuum?
Click to expand...
As explained above, you have a leak allowing air into the system.

If you are losing prime within a minute or two of shutting off the pump, you not only have a leak but your check valve is not holding.
 
Gentlemen,

Thank you for all your insights. After talking to Hayward directly today we found out that the pump I have is not right. It is a Max-Flo II 2hp and is not even rated to pump at 70 feet. It just falls off the chart after 60 feet (I am at 72 feet). It is self evident since my brother & I are able to prime the pump and have it running ok, but once we attach a 1 1/2" pool vacuum to the skimmer it restricts the flow enough that it cavitates the pump.

In the final analysis, I have the wrong pump. I need a tristar pump that delivers 94gpm at 70 feet. I would advise everyone that they closely look at their respective installation (feet of head) before deciding upon the right sized pump. I overlooked this and will have to get a better pump.

Once again, much thanks to everyone who replied, especially Bama & John.

Cheers, Nick
 
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