Forespar Marelon 3/4" Vented Loop/Siphon Valve
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Vented loops help protect onboard plumbing systems by breaking siphon effects when pumps are turned off. This Forespar Marelon 3/4" Vented Loop/Siphon Valve uses a one-way vent cap to allow air to enter the line while sealing when fluid is present, helping reduce the risk of backflow and flooding.
Key Features
- Designed for marine plumbing to help reduce dangerous back siphoning when the connected pump/system is off.
- Marelon™ construction: glass reinforced composite (helps resist corrosion for both the vent and loop).
- Air-entry vent cap with a one-way duck-bill style valve inside helps the loop vent the line when needed.
- Use in systems where you want anti-siphon protection above the waterline (e.g., sanitation/discharge and bilge-related plumbing).
Product Compatibility
- Marine plumbing systems requiring anti-siphon protection on discharge or outlet hoses
- Sanitation/head discharge plumbing
- Bilge pump outlet and related plumbing (where vented-loop installation above the waterline is appropriate)
- Engine/gen-set or other onboard equipment plumbing/discharge lines
Product Details
- Item: Forespar Marelon 3/4" Vented Loop/Siphon Valve
- SKU: 108-903001
- Barb/hose size: 3/4"
- Overall size: 4-1/2" H x 3-3/4" W
- UPC/GTIN (as provided in product data): 28026148728
- Product type: vented loop / siphon valve assembly
- Weight (as provided in product data): 113 grams
Parts Desk Insights
Best Use Case: Install as part of an anti-siphon setup on discharge/outlet plumbing where the vented loop is located above the waterline.
Common Issues: If siphoning still occurs, confirm the vented loop is positioned correctly above the waterline and that hose connections are secure and unobstructed; also ensure the vent-cap/one-way valve is functioning as intended and that particulate matter isn’t preventing proper sealing.
Related Products & Accessories
Browse related Bilge Pumps to complete the installation.
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.