Forespar Marelon 1/2" Vented Loop/Siphon Valve
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You have 30 days to request a return. All sale items are final sale.
The Forespar Marelon 1/2" Vented Loop/Siphon Valve is a glass-reinforced composite vented loop designed to help prevent dangerous back siphoning by allowing air to enter the discharge line when flow is not active.
Key Features
- Glass reinforced composite Marelon™ construction helps provide a durable, marine plumbing venting solution.
- Vented loop design allows air to enter the line to help prevent back siphoning/siphon-back effects.
- Built for above-the-waterline installation on head discharge systems, bilge pump, engine, generator sets, air conditioners, ballast tanks, and other onboard plumbing equipment.
Product Compatibility
- Head discharge and sanitation plumbing (above the waterline)
- Bilge pump discharge plumbing (above the waterline)
- Engine / gen-set / air conditioner discharge plumbing (above the waterline)
- Ballast tank plumbing (above the waterline)
- Other onboard discharge systems where anti-siphon protection is desired
Product Details
- • Manufacturer: Forespar
- • System/Material: Marelon™ (glass reinforced composite)
- • Size/Connection: 1/2"
- • Part/SKU: 108-903008
- • Type: Vented loop / siphon valve (anti-siphon venting component)
- • Product intent: Provides venting so the line can admit air when not in use, helping prevent back siphoning/siphon-back when pumps are turned off.
Parts Desk Insights
Best Use Case: Install vented loops above the waterline for discharge lines to help reduce the risk of back siphoning when the system shuts off.
Common Issues: If anti-siphon performance isn’t as expected, review: (1) that the vented loop is mounted above the waterline, (2) that the hose routing and connections match the intended 1/2" plumbing layout, and (3) that any related fittings/hoses are properly seated to avoid leaks or restrictions that could affect airflow.
Related Products & Accessories
- Browse Vented Loops & Replacement Vent Caps - Explore the matching Marelon vented loop sizes and related vent-cap components for your plumbing layout.
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 1-3 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.