Jandy VS FloPro Priming Failure: Air Leaks and Suction Issues

How Priming Works on the VS FloPro

When the VS FloPro starts, it runs at its programmed priming speed (default 2750 RPM) to evacuate air from the suction line and pull water from the pool into the pump. The pump body has a clear lid so you can visually confirm when water fills the strainer housing and air bubbles stop.

For installations with the pump above water level, the manual specifies a startup procedure: remove the lid, fill the basket with water, check for debris around the lid O-ring seat, replace the lid, then start the pump. For installations below water level, simply open the isolation valves and the pump will fill by gravity.

Step-by-Step Troubleshooting

Owner-Level Checks

Fill the pump with water manually

1. Turn off the pump and breaker.
2. Turn the locking ring counter-clockwise until "START" aligns with the ports. Remove the lid.
3. Fill the strainer basket housing with water using a garden hose.
4. Before replacing the lid, check for debris around the lid O-ring seat. Debris around the seat causes air leaks and makes priming difficult.
5. Replace the lid. Verify the "locked" indicators align with the pump ports. Hand-tighten only; do not use tools.
6. Open the air relief valve on the filter. Start the pump.
7. When water comes out of the filter air relief valve, close it.

Check valves and suction lines

1. Ensure all suction-side valves (skimmer, main drain) are fully open.
2. Verify no winterizing plugs are still in suction lines.
3. Check skimmer baskets for blockage that could restrict flow.
4. Make sure the pump unions on both suction and discharge are tight.

Tech-Level Checks

Inspect the lid seal

1. Remove the lid and examine the O-ring seal. It should be clean, flexible, and free of cracks.
2. Clean the O-ring seat on the pump body. Any debris here creates an air path.
3. The manual specifies: use only soapy water to install and lubricate the O-ring. Do not use lubricant or sealant, as these can damage the plastics.
4. A misaligned strainer basket can prevent the lid from seating properly, causing an air leak. Make sure the basket opening aligns with the suction pipe and drops easily into place. Do not force it.

Check for suction-side air leaks

1. With the pump running, look through the clear lid for air bubbles in the strainer housing. Persistent bubbles indicate a suction-side air leak.
2. Check all suction-side unions, valves, and pipe joints. Apply soapy water or use a smoke test to locate the leak.
3. Common leak points: pump lid O-ring, suction union O-rings, drain plugs, valve stems, and cracked pipe fittings.

Verify pump elevation and piping

1. The pump should be installed within 1 foot above water level for best results. It must not be elevated more than 5 feet per the manufacturer's recommendation, though it is NSF-certified for up to 10 feet.
2. Check suction piping for high points (inverted U-shapes) that can trap air. The suction pipe should slope continuously downward from the pump to the pool.
3. For installations more than 100 feet from the water, pipe size must be increased to the next larger size.

Increase priming speed

1. If priming at the default 2750 RPM is taking too long, increase the priming speed to 3450 RPM through the controller.
2. At 3450 RPM and 10 feet elevation, the pump should prime within 8 minutes.
3. If the pump still does not prime after following all steps, there is likely a suction leak. Repeat the air leak inspection.

Common Parts That Fix This Problem

• Lid seal O-ring (if cracked, flat, or deteriorated)
• Locking ring and O-ring assembly
• Drain plugs with O-rings (if leaking air through the drain ports)
• Pump strainer basket (if cracked or misaligned)
• Suction union O-rings and tailpieces

How to Prevent Priming Problems

• Install the pump as close to water level as possible. Shorter suction runs prime faster and more reliably.
• Avoid high points in suction piping that trap air.
• Clean the lid seal and seat every time you service the strainer basket.
• Replace the lid O-ring whenever it shows signs of wear, cracking, or compression set.
• After winterizing, always fill the pump housing with water before the first startup of the season.