Pump Priming Problem

[Scottish]

I have a 30,000 gallon pool with a separate pump for a waterfall. The pumps at least 8 feet above the pool. The return for the waterfall pump is at the main drain. The return line size is 3 inch. The pump HP is 2. I have lost prime on this pump and nothing that I have tried has gotten it back. Help me.

[PoolDoc]

Priming a 2" pump, with a 3" suction line and a 8' elevation change is gonna be tough, unless you can valve off and fill the suction line before starting the pump.

Send pictures of the site, as much of the suction piping as you can see, and the pump and surrounding piping to poolforum@gmail.com . . . or post them yourself using GDrive, Flickr, Picasa or Photobucket.

Also, please explain how you've primed before. If there's been a change, you might have a line cracked over winter, that's letting air into the suction pipe, and breaking the suction.

[Scottish]

Sent pic to email. I haven't had to prime it before. The motor went out so I had to turn it off. I just started working at this property and the guys told me to never turn this off because it was near impossible to reprime.

[PoolDoc]

I take it, this is not your own pool?

Regardless, it will take a lot more pictures than the one you sent, for me to work out your piping layout in my head . . . and that's a necessary first step toward helping you.

If you are a plumber, by chance, then this may help:

1. Install a check valve at the base or lowest point of the waterfall suction line.
2. Install a prime valve, consisting of a sill cock tapped into a 3" PVC pipe/socket hub connection, and a female/female 3/4" hose to hose connector.
3. Prime by filling till water exits the pump basket -- pump basket lid MUST be open BEFORE you begin filling. Shut off sill cock, close pump, and attempt prime.
4. Several attempts may be needed, because of air trapped upstream of the check valve.

If you can't send more pictures because of your employer's privacy concerns, you need to enlist your employer's plumber, and have him do the list above. Anybody who can afford to run a fountain 24/7 like that can afford to fix it right.

(And, if your employer can NOT afford those changes, look for another job! I've done work for some of those folks who had $500,000/year incomes . . . and $800,000/year lifestyles. My experience has been that they'll short the 'help' every time, before they'll give up the new Mercedes lease or the St. Bart's vacation they planned!)

[Scottish]

Fortunately, I happen to be a licensed plumber. I can do all of what you posted except the check valve,which is the most important,I'm sure.The suction line travels 4 feet before it goes into concrete.

[PoolDoc]

4 ft of 3" pipe will give you a water lift of about 1.5 gallons.

Install that check valve -- it needs to be a good one that's as close to bubble tight as possible -- as far from the pump as possible. Since you can't get close to the pool, you'll have to prime by cycling several times. You should be able to replace air with water in about 3' of pipe upstream of the check valve with each cycle. Basically, you'll (a) fill, (b) close the pump lid, (c) run the pump till you have air in the basket, (d) repeat.

Once you have it primed, it should remained primed with the pump off for a greater or lesser period, depending on how 'tight' the check valve is. If you also install a 3" valve close to the pump, you'll turn your current mess into a serviceable setup. The check valve will retain prime till air gets into the system, but when you open the system, you can keep prime by closing the suction valve before you do. Links below for appropriate gear.


Jandy 7307 Large Straight 2-1/2-Inch to 3-Inch Pool/Spa Check Valve (http://www.amazon.com/exec/obidos/ASIN/B002SG7O1C/poolbooks)
Banjo V300FP Polypropylene Ball Valve, Three Piece, Full Port, 3" NPT Female (http://www.amazon.com/exec/obidos/ASIN/B0079JWWNS/poolbooks)

The Banjo valve should remain easy to turn, with Teflon seals and a polypro ball. If you like, you can install the valve immediately upstream of the check valve. Since it's a full union valve, with SS bolts, you can fully service it, by buying a new valve, unbolting the old one, and slipping in the valve body from the new valve.

[PoolDoc]

Forgot -- here's the Jandy info:

http://www.zodiacpoolsystems.com/Products/Valves/Check-Valve.aspx
http://www.zodiacpoolsystems.com/~/media/Zodiac/Global/Downloads/SA/SA5250.ashx

and specs:
https://lh4.googleusercontent.com/-2ICRSyLYNdw/UztSvi1CPII/AAAAAAAAGfo/m3jpUQZD7SM/s812/Jandy%25207307%2520check%2520valve%2520specs.jpg