Can't get pumps to prime...Please help!

[marvelous]

I take care of 12 commercial pools and have no problems priming any of them, although some are more difficult than others.

But today I came across one that I cannot get primed. Here is the details, 2 1HP motors with service factor of 1.65, Challenger pumps with a manual Jandy valve at the exit of each pump. The pool is about fifty feet from the pumps. I removed one motor that I thought was having problems and replaced with a known good motor the impeller, diffuser and seals all looked ok, but I replaced just to be sure. Fired it up and nothing changed.

I close both main drain and skimmers fill up both strainers with water and close lids tightly, turn on motors and barely open up main drain or skimmer (I've tried both ways) one side pulls a little stream of water for a couple of minutes the other side just seems to be bubbling. I've tried with jandy valves open and closed with no luck, primed over and over again even ran hose for ten minutes down the main drain and skimmer lines in attempt to remove air. This is not a new pool so it does work, I just took managing it over today.

Should I leave jandy valves open or closed when trying to prime? I've tried both ways to no avail, pump just sounds different when I change but get no water either way.

Please Help!

 

[JasonLion]

Welcome to TFP!

I believe that you have to prime one pump at a time. Otherwise which ever pump gets started first pulls air backwards through the other pump and both lose prime.

Fill both skimmer baskets, close one pump's valve off and leave it powered off when you prime the other pump. Then, when the running pump is fully primed, open the valve on the pump that is off just a little while the other one is running to flush the air out. You should then have prime on both pumps. Turn them both off, open both valves, and turn them on together.

If you don't have separate power for each pump, I think you can probably still do it but I expect it to be more sensitive to timing and generally more problematic.

 

[marvelous]

Thanks I will try tomorrow am. So I dont turn on the second pump when I open the jandy valve just a little, the only time I turn on the second pump is when I turn both of them on together, correct?

 

[JamesW]

Why are there two pumps in this type of configuration? You would be much better off with a single variable speed pump, such as the Intelliflo.

It's possible that you have a suction side air leak.

What is the general state of the pool and equipment? Has it been well maintained?

What is the elevation of the pump in relation to the water level?

 

[JasonLion]

marvelous, you have it correct.

Opening the valve just a little on the turned off pump will allow a low volume reverse flow to flush the remaining air out of the pump. The key is to do it slowly enough that the running pump doesn't lose prime while that is happening, since it will be sucking in the air that was trapped in the turned off pump for a little while when you first open the valve.

As JamesW points out, this whole procedure will only work if there aren't any air leaks or other mechanical problems.

JamesW, using two pumps in parallel, while prone to several problems, such as the difficulty priming, is more energy efficient than using a single pump (variable speed or not). It is similar to the principal of running a two speed pump on low for twice as long, except we get the twice as long by having two pumps. There are some ways in which the parallel I just made breaks down, mostly because dynamic head doesn't really follow the same rules with two pumps in parallel instead of one at a lower speed, but the basic idea is the same. Anyway, this is almost never done on residential pools because it adds too much complexity, but you see it on commercial pools sometimes.

 

[marvelous]

Thanks so much! I am headed out now to try it, crossing my fingers. I dont think I have any suction leaks but could be wrong.

 

[marvelous]

Well I'm back and I have one pump primed running. Turned out some idiot put the wrong replacement diffuser and impeller on the one pump that wasnt doing anything. The one that is doing well had a broken O-ring seal on the diffuser, replaced it and started the pumps as you instructed and pump #1 primed within a minute. Then I bled the air out of the other one and then shut off and restarted both at the same time still nothing from pump #2. At least I have some circulation with pump 1 running. Monday will get the right impeller and diffuser for pump 2 and should be good to go.

Glad I found this sight, its great. I will try to help out others if I can