Jabsco Vented Loop, For Marine Toilets, Plastic, Anti-Siphon

Overview

The Jabsco Vented Loops is a range of anti-siphon plumbing fittings for Jabsco marine toilet installations where the toilet or pipework sits below the vessel's static or heeled waterline. The range covers 19 mm (3/4"), 25 mm (1"), and 38 mm (1-1/2") hose sizes, so the fitting can be matched to flush inlet or waste discharge plumbing rather than adapted with reducers.

Each vented loop uses a valve at the top of the loop to admit air and break siphon action after pumping. This helps stop water from continuing to travel through the pipework by gravity, which is a key safety concern on boats with through-hull toilet plumbing.

For correct siphon protection, the loop should be mounted at least 200 mm (8") above both the static and heeled waterlines. Placement matters: in inlet plumbing it belongs on the discharge side of the pump, not in the suction line between the seacock and pump.

Key features

• Anti-siphon fitting for manual and electric Jabsco marine toilets installed below the waterline.
• Valve at the top of the loop lets air enter the pipework to break siphon action after the toilet is pumped.
• Available for 19 mm (3/4"), 25 mm (1"), and 38 mm (1-1/2") hose connections.
• Molded plastic construction suits marine toilet plumbing where exposure to moisture and confined installation spaces are common.
• Supports safer routing for inlet and discharge hose loops when installed above the static and heeled waterlines.
• Useful for refits, toilet replacements, and service work where existing below-waterline pipework needs proper siphon protection.

Variants

This product is offered in three hose-size configurations for matching the vented loop to the existing toilet plumbing.

The hose size is the key difference between variants. The anti-siphon function and vented-loop purpose remain the same across the range.

• 29015-0000: 19 mm (3/4") hose size. This size is commonly used in flush water inlet loop plumbing on Jabsco toilet installations.
• 29015-0020: 25 mm (1") hose size. This size suits installations using 25 mm hose, including macerated waste discharge loop layouts where that hose size is specified.
• 29015-0010: 38 mm (1-1/2") hose size. This size is used for larger waste discharge hose runs, including toilet or holding tank discharge pipework.

Installation and fit

Install the vented loop at the highest practical point in the run, with the top of the loop at least 200 mm (8") above the waterline in both normal and heeled conditions. On sailing boats and narrow-beam vessels, the heeled waterline can be much higher than the static waterline, so the mounting height should be checked before the hose is cut.

For inlet installations, the fitting should not be placed in the suction line between the inlet seacock and the pump because the vent can admit air and stop the pump from priming. It belongs after the pump, between the pump and the toilet bowl, where siphon breaking is needed without interrupting suction.

Use on board

These vented loops are a practical match for boat owners, yards, and service technicians working on Jabsco heads where below-waterline plumbing needs a proper siphon break. They are especially relevant during toilet upgrades, hose replacement, seacock service, or any refit where the original hose routing is being checked for flooding protection.