Groco Bronze Vented Loop, 3/4 Inch Hose, HVL-750

The Groco HVL-750 is a bronze vented loop built to protect boats whose head, sink, or other through-hull drain is mounted below the waterline. When a fixture sits below the waterline, a straight hose run can siphon seawater back into the boat once the pump stops or the fixture is opened, and a vented loop breaks that siphon before it can flood the line or the bilge. The HVL-750 uses a simple valve mechanism mounted at the high point of the loop: as long as the loop is installed above the waterline, the valve admits air the instant siphoning begins, breaking the vacuum and stopping backflow. A threaded cap on top of the valve body allows the valve to be removed for cleaning and inspection without cutting into the hose run, which matters because these valves can foul with salt, scale, or marine growth over time and need periodic servicing to keep functioning correctly. The body is cast bronze for corrosion resistance in a saltwater environment, and the fitting is sized for 3/4 inch hose, matching common marine sanitation and drain hose diameters. This is a functional plumbing safety component rather than a cosmetic fitting, and it should be installed per standard marine plumbing practice at the highest point of the loop, above the waterline, to work as intended.

Specifications

• Brand: Groco
• Manufacturer Part Number: HVL-750
• Product Type: Vented Loop
• Material: Bronze
• Exterior Finish: Bronze
• Thread/Hose Size: 3/4 inch
• Valve Type: Vented loop with threaded cleaning/inspection cap
• Item Dimensions: 8 x 7 x 3 inches
• Weight: 1.9 pounds
• Quantity: 1

Frequently Asked Questions

What does the Groco HVL-750 vented loop actually do? It breaks a siphon on a below-waterline drain line, such as a head or sink discharge, by admitting air through a valve at the top of the loop so seawater cannot be pulled back into the boat once pumping stops.

What hose size does the HVL-750 fit? The Groco HVL-750 is sized for 3/4 inch hose.

What is the HVL-750 made of? It is made of bronze, chosen for its corrosion resistance in saltwater plumbing systems, with a bronze exterior finish.

How do I clean or service the vented loop? The HVL-750 has a threaded cap on the valve body that can be unscrewed to access and clean the internal valve without disconnecting the hose from the fitting.

Where should this vented loop be installed? Like any vented loop, the HVL-750 needs to be mounted at the highest point of the drain hose run and above the boat's waterline in order to break a siphon correctly.

What are the dimensions of the HVL-750? The Groco HVL-750 measures 8 x 7 x 3 inches.

How much does the HVL-750 weigh? The vented loop weighs 1.9 pounds.

Is the HVL-750 sold as a single unit? Yes, the Groco HVL-750 vented loop is sold individually as one unit.

Why would I need a vented loop instead of running the hose straight? A below-waterline fixture connected with a straight hose run can siphon seawater back into the boat when the pump is off; the HVL-750 prevents this by breaking the siphon with its vent valve.

Can the HVL-750 be inspected without removing it from the boat? Yes, the threaded cap on the Groco HVL-750 allows inspection and cleaning of the valve in place, without removing the fitting from the hose line.

Does the HVL-750 include the mounting hardware or hose clamps? The dossier for the Groco HVL-750 does not list included hose clamps or mounting hardware; it covers the bronze vented loop fitting itself.

Is the HVL-750 suitable for marine sanitation systems? Yes, the Groco HVL-750 is designed as a vented loop for marine drain lines, including sanitation discharge lines mounted below the waterline, using 3/4 inch hose.