GROCO Bronze Vented Loop HVL-1000, 1 Inch Hose Anti-Siphon Valve

The GROCO HVL-1000 is a bronze vented loop built to accept 1 inch hose, designed to prevent siphoning and backflow in below-waterline plumbing runs such as head discharge, raw water washdown, and other through-hull applications where a loop must be installed above the waterline. Bronze construction resists corrosion in marine environments and provides long service life compared to plastic alternatives. The fitting measures 8 inches in length by 7 inches in width, with a 1 inch outside diameter and a nominal wall thickness of 0.125 inches, giving it the rigidity needed to hold its shape and seal reliably under vacuum and pressure conditions typical of onboard plumbing systems.

Installed at the high point of a hose run, the vented loop opens to atmosphere when the system loses vacuum, breaking any siphon before water can be drawn back through a through-hull fitting below the waterline. This is a critical safety component for preventing unwanted flooding in systems like marine heads. The GROCO HVL-1000 is compatible with standard 1 inch marine hose used throughout the boat's plumbing system.

Specifications

• Brand: Groco
• Manufacturer Part Number: HVL-1000
• Hose Size: 1 inch
• Outside Diameter: 1 inch
• Nominal Wall Thickness: 0.125 inches
• Product Length: 8 inches
• Product Dimensions: 8 inches L x 7 inches W
• Weight: 1.9 pounds
• Material: Bronze
• UPC: 742985003071

Frequently Asked Questions

What is the GROCO HVL-1000 used for? The HVL-1000 is a bronze vented loop that breaks siphon action in below-waterline hose runs, preventing water from being drawn back through a through-hull fitting into the boat.

What hose size does the HVL-1000 fit? This vented loop is sized for 1 inch hose, matching its 1 inch outside diameter.

What material is the HVL-1000 made from? Bronze, chosen for its corrosion resistance in marine plumbing applications.

How much does the HVL-1000 weigh? The GROCO HVL-1000 weighs 1.9 pounds.

What are the dimensions of the HVL-1000 vented loop? It measures 8 inches in length by 7 inches in width, with a nominal wall thickness of 0.125 inches.

Where should a vented loop like the HVL-1000 be installed? Vented loops are installed at the highest point of a hose run, above the waterline, so they can open to atmosphere and break any siphon before it can pull water back into the boat.

Is the HVL-1000 made of plastic or metal? It is a bronze fitting, not plastic, giving it added durability and corrosion resistance over plastic vented loops.

What is included when I order the HVL-1000? The HVL-1000 ships as the complete bronze vented loop fitting sized for 1 inch hose.

Why does a marine head or through-hull system need a vented loop? Without a vented loop such as the HVL-1000, a loss of vacuum in a below-waterline hose run can allow water to siphon back through the through-hull, leading to unwanted flooding.

Does the HVL-1000 work with standard marine hose? Yes, it is designed to accept 1 inch marine hose commonly used in onboard plumbing systems.